岷江冷杉林群落几种树苗对光强的响应与适应

在青藏高原东部的亚高山针叶林区，如何尽快恢复这一生态脆弱地区的植被，改变生态环境恶化的趋势，是一个十分重要的课题。光一直被认为是植物种间相互替代，尤其是森林演替过程中植物相互替代或植被恢复中的关键环境要素之一。植物能否适应林冠下或林窗中异质的、或多变的光照条件，对其在林中的生存、分布、更新以及森林动态都是非常重要的。 本文以青藏高原东部亚高山针叶林的主要森林类型——岷江冷杉林群落的几种树苗为研究对象，采用实验生态学、生理及生物化学等方法，通过模拟针叶林不同大小林窗内光照强度的变化，在中国科学院茂县生态站内采用遮荫处理设置6个光照梯度（100、55、40、25、15与7%全光照），来研究具有不同喜光特性的植物对光强的响应与适应机制，其研究结果可为揭示亚高山针叶林的演替规律、以及人工林下幼苗的存活与定居提供科学依据，也能为苗木的生产与管理提供科学指导，尤其是对针阔树种在不同光强下的响应与适应的比较研究，能为如何将阔叶树种整合到人工针叶林中提供新的思路。 光强对植物生长的影响 光强对植物的生长具有重要作用，不同植物在各自适宜的光强梯度下才能生长良好。通过一个野外盆栽实验，来研究不同光强对植物生长的影响（第三章）。主要研究结果如下，低光强下植物株高/茎生物量增加，说明植物会将生物量更多用于高生长，以便有效地拦截光资源；在强光下，植物将生物量更多地向根部分配，使得植物在强光下能够吸收更多的水分，而避免干旱胁迫。 在第一个生长季节，以相对生长速率（RGR）表示，红桦和青榨槭在100%全光照下RGR最大，粗枝云杉在55%最大，岷江冷杉在25-40%下较好；然而，在第二个生长季节，2种阔叶树的相对生长速率（RGR）的适宜光强则变为25-55%，云杉为55-100%，而冷杉为25-100%。可见，从第一年到第二年，2种阔叶树苗更适宜在部分荫蔽的条件下生长；而2种针叶树苗对光的需求则逐渐增加，这可能是增加对根生物量相对投资的结果，因为以这种方式，强光下生长的针叶树幼苗更能保持其内部水分平衡，其生长不会因干旱胁迫而受到严重影响。另外，严重遮荫会引起冷杉幼苗死亡。 植物对光强的生理适应 植物可以通过自身形态和生理特征的调整，来发展不同的光能利用策略从而能够在林中共存。通过一个野外盆栽实验，研究了不同光强下生长的几种树苗的生理特征（第四章）对不同光强的响应与适应。结果显示：强光下，粗枝云杉和红桦的光合能力增加，而岷江冷杉和青榨槭在中度遮荫（25-55%）的条件下光合能力最大。植物叶氮和叶绿素含量增高，而光补偿点和暗呼吸速率降低，这些都是植物对低光环境的适应性反应；而强光下植物叶片和栅栏组织变厚，是对强光的一种保护性反应。 植物对光的可塑性反应 不同植物会表现出对光适应有利的生理和形态可塑性反应。本文对第三章、第四章的实验数据进行可塑性指数分析，来研究植物对光强的表型可塑性反应（第五章）。结果显示，生理特征调整是植物对不同光环境的主要适应途径。红桦和青榨槭的可塑性指数平均值要大于粗枝云杉和岷江冷杉，充分表明这2种阔叶树在生理和形态上较强的可塑性更有利于对光环境的适应，而具有比耐荫树种更强的适应能力。另外，2种针叶树相比，云杉的适应性更强。本研究结果支持树种的生理生态特性决定了其演替状况和生境选择的假说。 植物的光抑制与防御 当植物叶片吸收了过多光能，会发生光抑制现象。植物对光抑制的敏感性及防御能力对其生长具有重要意义。本文通过两个野外盆栽实验，研究了生长在强光下（第六章）和变化光强下（第八章）植物的光抑制现象及其防御策略。结果表明，在强光下或从遮荫状态转入强光下，植物都会发生光抑制，其对光抑制的敏感性与植物的耐荫性（或喜光）和演替状态有密切联系。长期生长在强光下的植物受到光抑制是可恢复的，而当处于荫蔽环境的植物突然暴露于强光下时，受到的光抑制不能完全恢复，可能是（部分）光合机构受到破坏的缘故。粗枝云杉和青榨槭防御光抑制伤害的能力较强，热耗散是其防御光抑制的主要途径。长期的强光作用能使岷江冷杉和红桦发生严重光抑制，甚至光伤害，而红桦能够通过“凋落老叶，萌发新叶”的途径来适应新的强光环境。 How to restore the vegetation of subalpine coniferous forest in eastern Qinghai-Tibet Plateau, and change the trend of ecological deterioration is a very important issue. Acclimation of tree seedlings to different and varing light environment affects to a great extent the successful regeneration and establishment of subalpine coniferous forests in southwestern China’s montane forest areas, because the ability to respond to such changing resource are commonly assumed to be critical to plant success, and have a growth advantage than others. In this paper, several species seedlings in Abies faxoniana community were chosed to study the response and adaptation to light intensity and the interspecific differences of adaptability in six shaded sheds (100, 55, 40, 25, 15 and 7% of full sunlight) in the Maoxian Ecological Station of Chinese Academy of Sciences. Our results could provide a strong theoretical evidence for understanding the forest succession laws of subalpine coniferous forests, and the survival and settlement of seedlings under plantations, and provide scientific direction for the production and management of seedlings, especially the comparative studies of the acclimation to light between the conifer and broadleaf trees could provide new ideas for how to integrate the broad-leaved trees into the artificial coniferous forest. Growth under different light intensity Light intensity plays an important role on plant growth. One field experiments was conducted to study the growth of tree seedlings of Picea asperata, Abies faxoniana, Betula albo-sinensis and Acer davidii under different light intensities. The results showed that plants under low light environment could increase the specific stem length (stem length/ stem dry mass), in order to effectively intercept light resources, while biomass greater allocation to the roots, could make plants under high light environment absorb more water, and avoid drought stress. During the first growing season, the relative growth rates (RGRs) of Betula albo-sinensis and Acer davidii had the greatest values under the 100% of full light, for 55% of Picea asperata, and for 25-40% of Abies faxoniana. However, in the second growing season the the relative growth rates of the two broad-leaved trees changed and were appropriate for 25-55% of full light, for 55-100% of spruce, and for 25-100% of fir. Thus, from the first year to the second year, two broad-leaved seedlings maybe more suitable to partly shading environment, and two coniferous seedlings would have an increase in light demand, which may be an increased root biomass investment. Because in this way, seedlings grown under high light could better maintain their internal water balance, and thus its growth would not be seriously affected by drought stress. In addition, serious shading would cause fir seedlings to die. Acclimation of physiology to light Plants could coexist in forest ecosystem by forming different strategies of light use. One field experiments was conducted to study the acclimation of tree seedlings to different light intensity of Picea asperata, Abies faxoniana, Betula albo-sinensis and Acer davidii. The results showed that the photosynthetic capacity of Picea asperata and Betula albo-sinensis exhibited a general tendency of increase with more light availability; but for Abies faxoniana and Acer davidii seedlings, their highest values of the same parameters were found under intermediate light regime (i.e. 25-55% of PFD relative to full sunlight). Plants under low light environment could increase the specific stem length (stem length/ stem dry mass), in order to effectively intercept light resources. Leaf nitrogen and chlorophyll content increased, while dark respiration rate and light compensation points decreased, all of which were adaptive response to the low light environment. On the contrary, plants under high light environment had the thicken leaves and palisade tissue, which was a protective response to high light. Phenotypic plasticity to light Phenotypic plasticity can be exhibited in morphological and physiological processes. Physiological characteristical adjustment is the main for plant adaptation to different light environment.The means of plasticity indexes for Betula albo-sinensis and Acer davidii seelings were greater than Picea asperata and Abies faxoniana, amplied that the two broad-leaved trees were much more adaptable to the environment. In addition, spruce had the higher adaptablity than fir. The findings supported the hypothesis that the ecological characteristics of the species determined the biological status and its biological habitat selection. Photoinhibition and photoprotection to light Compared with conifer, broad-leaved trees could better change leaf morphology and adjust biomass allocation to adapt to changing light environment. However, excess light can photoinhibit photosynthesis and may lead to photooxidative destruction of the photosynthetic appatus. Two field experiments were conducted to study the photoinhibition of photosynthesis. The results showed that when plants grown under high light environment or plants transferred from low to high irradiance, the four tree seedlings would undergo a period of photoinhibition. In four species, photoinhibited leaves could recover to initial photosynthetic rates when they were long-term planted under high light environment. However, when plants were suddenly exposed to high irradiance, this photoinhibition could not be reversible, may be the photosynthesis apparatus were (or partly) photooxidatively destructed.

遮荫与外源脱落酸喷施对粗枝云杉(Picea asperata Mast.)不同种群抗旱性的影响

本研究通过粗枝云杉不同种群进行的温室半控制试验，采用植物生态学、生理学和生物化学的研究方法，系统地研究了粗枝云杉不同种群抗旱性的生长、形态、生理和生化机理，并结合有关研究进行综合分析，得出主要研究结论如下： 1.粗枝云杉对干旱胁迫的综合反应 粗枝云杉在干旱胁迫下的适应机制为：（1）相对生长速率及植株结构的调整：干旱胁迫下虽然植株相对生长速率显著降低，且有相对较多的生物量向根部分配，但并未发现细根/总根比增加。（2）粗枝云杉对干旱胁迫的光合作用表现为：干旱胁迫显著地降低了控制的理想条件下的气体交换，但干旱胁迫对PSII最大光化学效率（Fv/Fm）没有影响，表明干旱并未影响到光合机构。（3）干旱还影响了很多生理生化过程，包括渗透调解物质（游离脯氨酸）、膜脂过氧化产物、脱落酸（ABA）含量的增加，以及保护酶活性的升高。这些结果证明植物遭受干旱胁迫后发生了一系列的形态、生理和生化响应，这些变化能提高干旱时期植物的存活和生长能力。 2.粗枝云杉不同种群对干旱胁迫反应的种群差异 粗枝云杉三个种群－干旱种群（四川丹巴和甘肃迭部）和湿润种群（四川黑水）对干旱适应不同，这种不同应归因于它们采用的用水策略不同：在水分良好和干旱胁迫条件下，受试种群在相对生长速率和水分利用效率（WUE）方面都表现出显著的种群间差异。与湿润种群相比，干旱种群在两种水分条件下有更高的WUE。粗枝云杉不同种群的碳同位素组分（δ13C）只在干旱胁迫下有显著差异，并且这种差异在水分良好时比干旱胁迫条件下小，说明生理响应和干旱适应性之间的关系受植物内部抗旱机制和外部环境条件（如水分可利用性）或两者互作效应的影响。这些结果说明干旱种群和湿润种群所采用的用水策略不同。干旱种群有更强的抗旱能力，采用的是节水型的用水策略，而湿润种群抗旱能力较弱，采用的是耗水型的用水策略。 3. 遮荫对粗枝云杉不同种群抗旱性影响 干旱胁迫显著降低了全光条件下叶相对含水量（RWC）、相对生长速率、气体交换参数、PSII的有效量子产量（Y），提高了非光化学猝灭效率（qN）、水分利用效率、脯氨酸（PRO）积累、脱落酸（ABA）含量及保护酶活性。然而这种变化在遮荫条件下不明显。我们得出结论适度遮荫降低了干旱对植物的胁迫作用。另一方面，在干旱条件下，与湿润种群相比，干旱种群抗旱性更强，表现在干旱种群净光合速率与单位重量上叶氮含量（Nmass）降低较少。另外，干旱种群表现出更为敏感的气孔导度，更高的热耗散能力（qN）能力、用水效率、ABA积累、保护酶活性，以及更低的总用水量、相对生长速率。这一结果表明这两种群采用不同的生理策略对干旱和遮荫做出反应。许多生长和生理反应差异与这两个种群原产地气候条件相适应。 4. 外源脱落酸(ABA)喷施对粗枝云杉不同种群抗旱性影响 外源ABA喷施在干旱和水分良好条件下均不同程度地提高了根/茎比，表明根和茎对ABA敏感程度不同。实验结果还表明，外源ABA喷施对这两个种群在干旱胁迫期间影响不同。干旱胁迫期间，伴随着ABA喷施，湿润种群净光合速率(A)显著降低，而干旱种群净光合速率变化不明显。另一方面，外源ABA喷施显著提高了干旱条件下干旱种群的单位叶面积重（LMA）、根/茎比、细根/总根（Ft）比、水分利用效率（WUE）、ABA含量, 以及保护酶活性。然而，外源ABA喷施对湿润种群的上述测定指标没有显著影响。这一结果表明干旱种群对外源ABA喷施更为敏感, 反应在更大的气孔导度降低，更高的生物量可塑性，及更高的水分利用效率、ABA含量和保护酶活性。综上所述，我们得出结论，粗枝云杉对外源ABA敏感性因种群的不同而不同。该研究结果可为两个明显不同种群在适应分化方面提供强有力的证据。 Arid or semi-arid land covers more than half of China's land territory. In arid systems, severe shortages of soil water often coincide with periods of high temperatures and high solar radiation, producing multiple stresses on plant performance. Protection from high radiation loads in shaded microenvironments during drought may compensate for a loss of productivity due to reduced irradiance when water is available. Additionally, ABA, a well-known stress-inducible plant hormone, has long been studied as a potential mediator for induction of drought tolerance in plants. Picea asperata Mast., which is one of the most important tree species used for the production of pulp wood and timber, is a prime reforestation species in western China. In this experiment, different population of P. asperata were used as experiment material to study the adaptability to drought stress and population differences in adaptabiliy, and the effects of shade and exogenous abscisic acid (ABA) application on the drought tolerance. Our results cold provide a strong theoretical evidence and scientific direction for the afforestation, and rehabilitation of ecosystem in the arid and semi-arid area, and provide a strong evidence for adaptive differentiation of different populations, and so may be used as criteria for species selection and tree improvement. The results are as follows: 1. A large set of parallel response to drought stress Drought stress caused pronounced inhibition of the growth and increased relatively dry matter allocation into the root; drought stress also caused pronounced inhibition of photosynthesis, while drought showed no effects on the maximal quantum yield of PSII photochemistry (Fv/Fm) in dark-adapted leaves, indicating that drought had no effects on the primary photochemistry of PSII. However, in light-adapted leaves, drought reduced the quantum yield of PSII electron transport (Y) and increased the non-photochemical quenching (qN). Drought also affected many physiological and biochemical processes, including increases in superoxide dismutase (SOD), ascorbate peroxidase (APX) activities, malondialdehyde and ABA content. These results demonstrate that there are a large set of parallel changes in the morphological, physiological and biochemical responses when plants are exposed to drought stress; these changes may enhance the capability of plants to survive and grow during drought periods. 2. Difference in adaptation to drought stress between contrasting populations of Picea asperata There were significant population differences in growth, dry matter allocation and water use efficiency. Compared with the wet climate population (Heishui), the dry climate population (Dan ba and Jiebu) showed higher LMA, fine root/total root ratio and water use efficiency under drought-stressed treatments. The results suggested that there were different water-use strategies between the dry population and the wet population. The dry climate population with higher drought tolerance may employ a conservative water-use strategy, whereas the wet climate population with lower drought tolerance may employ a prodigal water-use strategy. These variations in drought responses may be used as criteria for species selection and tree improvement. 3. The effects of shade on the drought tolerance For both populations tested, drought resulted in lower needle relative water content (RWC), relative growth rate (RGR), gas exchange parameters and effective PSII quantum yield (Y), and higher non-photochemical quenching (qN), water use efficiency (WUE), proline (PRO) and abscisic acid (ABA) accumulation, superoxide dismutase (SOD), ascorbate peroxidase (APX) activities as well as malondialdehyde (MDA) levels and electrolyte leakage in sun plants, whereas these changes were not significant in shade plants. Our study results implied that shade, applied together with drought, ameliorated the detrimental effects of drought. On the other hand, compared with the wet climate population, the dry climate population was more tolerant to drought in the sun treatment, as indicated by less decreases in A and mass-based leaf nitrogen content (Nmass), more responsive stomata, greater capacity for non-radiative dissipation of excitation energy as heat (analysed by qN), and higher WUE，higher level of antioxidant enzyme activities，higher ABA accumulation as well as lower MDA content and electrolyte leakage. Many of the differences in growth and physiological responses reported here are consistent with the climatic differences between the locations of the populations of P. asperata. 4. The effects of exogenous abscisic acid (ABA) application on the drought tolerance For both populations tested, exogenous ABA application increased root/shoot ratio (Rs) under well-watered and drought-stressed conditions, indicating that there was differential sensitivity to ABA in the roots and shoots. However, it appeared that ABA application affected the two P. asperata populations very differently during drought. CO2 assimilation rate (A) was significantly decreased in the wet climate population, but only to a minor extent in the dry climate population following ABA application during soil drying. On the other hand, ABA application significantly decreased stomatal conductance (gs), transpiration rate (E) and malondialdehyde (MDA) content, and significantly increased leaf mass per area (LMA), Rs, fine root/total root ratio (Ft), water use efficiency (WUE), ABA contents, superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) activities under drought condition in the dry climate population, whereas ABA application did not significantly affect these parameters in the wet population plants. The results clearly demonstrated that the dry climate population was more responsive to ABA application than the wet climate population, as indicated by the strong stomata closure and by greater plasticity of LMA and biomass allocation, as well as by higher WUE, ABA content and anti-oxidative capacity to defense against oxidative stress, possibly predominantly by APX. We concluded that sensitivity to exogenous ABA application is population dependent in P. asperata. Our results provide strong evidence for adaptive differentiation between populations of P. asperata.

青杨组(Section Tacamahaca Spach)杨树不同种群对土壤干旱和重金属锰污染的生态生理响应

土壤是人类赖以生存的自然环境和农业生产的重要资源，世界面临的粮食、资源和环境问题与土壤密切相关，目前危害土壤的主要因素是干旱和重金属污染。杨树具有适应性强、生长快和丰产等特性，本论文以青杨组杨树为模式植物，采用植物生态、生理及生物化学等方法，研究杨树对土壤干旱和锰胁迫的生态生理反应以及种群间差异，研究成果可为我国干旱半干旱地区营造人工林、防止沙漠化提供理论依据，也为恢复与重建重金属污染地区退化生态系统提供科学指导。主要研究结果如下： 1. 青海杨不同种群对干旱胁迫的响应差异 干旱胁迫显著降低了两个青海杨种群（干旱种群和湿润种群）生物量积累，包括株高、基径、干物质积累等，通过植物结构的调整，有更多的生物量向根部分配。干旱胁迫还显著降低了叶绿素和类胡萝卜素含量，增加了游离脯氨酸和总氨基酸含量。另一方面，干旱胁迫诱导了活性氧的积累，作为第二信使，激活了抗氧化系统，包括抗坏血酸（ASA）含量和酶系统如超氧化物歧化酶（SOD），愈创木酚过氧化物酶（GPX），抗坏血酸过氧化物酶（APX）和谷胱甘肽还原酶（GR）。这样，杨树既有避旱机制又有耐旱机制，使其在干旱胁迫下有相当程度的可塑性。与湿润种群相比，干旱种群杨树有更多的生物量分配到根部，积累了更多的游离脯氨酸和总氨基酸来进行渗透调节，并且有更有效的抗氧化系统，包括更高含量的ASA 和更高活性的APX 和GR，这些使得干旱种群杨树比湿润种群杨树对干旱有更好的耐性。 2. 喷施硝普钠（SNP）对青海杨阿坝种群干旱胁迫耐性的影响 干旱胁迫显著的降低了青海杨阿坝种群的生长和生物量积累以及叶片相对含水量，还诱导了脯氨酸的合成以进行渗透调节。干旱胁迫下过氧化氢（H2O2）显著累积从而造成对膜脂和蛋白的伤害，使得丙二醛和蛋白羰基含量升高。干旱胁迫下喷施SNP可以减轻干旱胁迫造成的伤害，包括增加叶片的相对含水量，增加脯氨酸和总氨基酸的积累，并激活抗氧化酶系统如SOD，GPX和APX，从而减少丙二醛（MDA）和蛋白羰基（C＝O）的积累，但是在水分良好情况下SNP的效果不显著。 3. 青杨不同种群对锰胁迫的生长与形态响应差异 在同一锰浓度下，干旱种群的耐性指数都要高于湿润种群，这表明青杨对干旱和高锰胁迫具有交叉耐性。两个种群的株高，生物量和叶绿素含量都随锰浓度的升高而逐渐下降。就累积浓度而言，0 和0.1 mM 锰胁迫下，干旱种群积累的锰浓度要高于湿润种群，而在高浓度锰胁迫下(0.5 和1 mM)，湿润种群要高于干旱种群。在0，0.1 和0.5 mM下，锰大多积累在根中，叶片次之，茎中最少。而在1 mM，锰更多的积累在叶片中。就累积总量而言，在各个锰浓度胁迫下，根，茎和叶相比，两个种群青杨都是叶片累积的锰总量要高于根和茎。两个种群间比较，对照中没有显著区别，0.1 mM 锰胁迫下，湿润种群根中累积的锰要高于干旱种群，而在地上部中，干旱种群要高于湿润种群。而0.5 和1 mM 锰胁迫下，根、叶、茎+叶、根+茎+叶中，锰累积总量都是湿润种群高于干旱种群。锰胁迫下，青杨叶片数和叶面积包括总叶面积和平均叶面积都显著降低。叶片横切面的光学显微观察结果表明未经锰胁迫的栅栏组织的细胞饱满，海绵组织发达、清晰；胁迫后杨树叶片栅栏组织细胞出现不同程度的皱缩，海绵组织几乎不可见，此外还发现输导组织在胁迫下密度变小和分生组织严重割裂等现象。 4. 青杨不同种群对锰胁迫的生理与生化响应差异 青杨两个种群脱落酸（ABA）含量在锰胁迫下都显著增加，干旱种群的增幅更大。三种多胺含量在锰胁迫下显示了不同的响应趋势：腐胺在两个种群的各个锰处理下都增加，亚精胺只在干旱种群中显著增加，而精胺除了干旱种群在1 mM 下有所增加外，在锰胁迫下变化很小。谷胱甘肽含量随锰浓度升高而增加，在0.5 mM 锰时达到最高值，1mM 时有所下降。植物络合素（PCs）含量与非蛋白巯基（NP-SH）趋势相似，随锰浓度的升高而增加，且干旱种群中含量要高于湿润种群。锰处理还引起氧化胁迫，表现为过氧化氢和丙二醛含量增加。SOD 活性在湿润种群中，在0 到0.5 mM 锰胁迫下活性升高，但在1 mM 锰胁迫时，其活性有所下降。而在干旱种群中，SOD 活性变化较小，并始终维持在一个较高的水平。APX 活性在两个种群中都随锰浓度的升高而增加，干旱种群活性要高于湿润种群。锰胁迫还显著增加了酚类物质的含量，同时GPX 和多酚氧化酶（PPO）活性也随锰浓度的升高而增加。干旱种群的酚类含量和GPX 与PPO 活性都要高于湿润种群。锰胁迫还改变了氨基酸的含量和构成，根据锰胁迫下浓度变化的不同，可以将游离氨基酸分为三组：第一组包括，谷氨酸，丙氨酸和天门冬氨酸，这一组氨基酸含量在锰胁迫下有所下降。第二组包括缬氨酸，亮氨酸和苏氨酸含量在锰胁迫下基本不变化或变化很小。剩下的氨基酸为第三组，这组氨基酸含量在锰胁迫下显著增加，而根据增加的幅度又可以将它们分为两个亚组，丝氨酸，酪氨酸，苯丙氨酸，组氨酸和脯氨酸，在1 mM 下的含量是对照的4 倍以上。异亮氨酸，赖氨酸，精氨酸和甘氨酸含量在1 mM 下是对照含量的2 倍以下。同时，同一锰浓度下，干旱种群比湿润种群积累的氨基酸含量要高。 Soil is the indispensable environment for human survival and important resource foragriculture development. Food and environmental problems facing the world are all closelyrelated to soil and nowadays it is threatened by many factors, among which drought stress andheavy metal pollution are the most serious ones. Poplars (Populus spp.) are importantcomponents of ecosystem and suitable as a source of fuel, fiber and lumber due to their fastgrowth. In this study, different populations of Section Tacamahaca spach were used as modelplants to investigate the adaptability to drought stress and manganese toxicity and differencesbetween populations from dry and wet climate regions. Our results can provide theoreticalevidence for the afforestation and prevention of desertification in the arid and semi-arid areas,and also can supply scientific direction for the reconstruction and rehalibitation of ecosystemscontaminated by heavy metals. The results are as follows: 1. Differences in ecophysiological responses to drought stress in two contrastingpopulations of Populus przewalskii Drought stress not only significantly affected dry mass accumulation and allocation, butalso significantly decreased chlorophyll pigment contents and accumulated free proline andtotal amino acids. On the other hand, drought also significantly increased the levels ofabscisic acid and reactive oxygen species, as secondary messengers, to induce the entire set ofantioxidative systems including the increase of reduced ascorbic acid content and the activities of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase and glutathioneredutase. Thus the combination of drought avoidance and tolerance mechanisms conferredpoplar a high degree of plasticity in response to drought stress. Compared with the wetclimate population, the dry climate population showed lower dry matter accumulation andallocated more biomass to root systems, and accumulated more free proline and total aminoacids for osmotic adjustment. The dry climate population also showed more efficientantioxidant systems with higher content of ascorbic acid and higher activities of ascorbateperoxidase and glutathione redutase than the wet climate population. All these made the dryclimate population superior in adaptation to drought stress than the wet climate population. 2. Effect of exogenous applied SNP on drought tolerance in Populus przewalskii Drought stress significantly increased hydrogen peroxide content and caused oxidativestress to lipids and proteins assessed by the increase in malondialdehyde and total carbonylcontents, respectively. The cuttings of P. przewalskii accumulated proline and other aminoacids for osmotic adjustment to lower water potential, and activated the antioxidant enzymes such as superoxide dismutase, guaiacol peroxidase and ascorbate peroxidase to maintain thebalance of generation and quenching of reactive oxygen species. Moreover, exogenous SNPapplication significantly heightened the growth performance of P. przewalskii cuttings underdrought treatment by promotion of proline accumulation and activation of antioxidant enzymeactivities, while under well-watered treatment the effect of SNP application was very little. 3. Morphological responses to manganese toxicity in the two contrasting populations ofPopulus cathayana High concentration of manganese caused significant decrease in shoot height andbiomass accumulation. The tolerance index of the dry climate population was significantlyhigher than that of the wet climate population, suggesting the superior Mn tolerance in theformer and the existence of cross-tolerance of drought stress and high Mn toxicity. Injuries tothe leaf anatomical features were also found as the reduced thickness in palisade and spongyparenchyma, the decreased density in the conducting tissue and the collapse and split in themeristematic tissue in the central vein. As for the Mn concentrations in the plant tissues, under0, 0.1 and 0.5 mM, most of the Mn accumulated in the roots, then leaves, and stem the least, while under 1 mM, most of the Mn accumulated in the leaves. As far as the total amounts ofMn extraction are concerned, the leaf extracted more Mn than the root and stem in the twopopulations under various Mn concentrations. There is no difference between the twopopulations under control. Under 0.1 mM, the wet climate population extracted higher Mn inthe root than the dry climate population, while in the shoot, the dry climate populationextracted much more Mn. Under 0.5 and 1 mM, the wet climate population translocated moreMn both in the root and the shoot than the dry climate population. 4. Physiological and biochemical responses to manganese toxicity in the two contrastingpopulations of Populus cathayana Mn treatment resulted in oxidative stress indicated by the oxidation to lipids, proteinsand DNA. A regulated network of defence strategies was employed for the chelation,detoxification and tolerance of Mn including the enhanced synthesis of ABA and polyamines,the accumulation of free amino acids, especially His and Pro, and the activation of theenzymes superoxide dismutase and guaiacol peroxidase. Contents of non-protein thiol,reduced glutathione, phytochelatins and phenolics compounds and activities of superoxide dismutase, guaiacol peroxidase and polyphenol oxidase also increased significantly forantioxidant or chelation functions. The wet climate population not only accumulated lessabscisic acid, free amino acids, phytochelatins and phenolics compounds, but also exhibitedlower activities of superoxide dismutase, guaiacol peroxidase and polyphenol oxidase thusresulting in more serious oxidative damage and more curtained growth.

三种豆科灌木对干旱胁迫的响应与适应

干旱胁迫是全球范围内影响植物生存、生长和分布的重要环境因子。岷江上游干旱河谷区，由于生态环境的脆弱性和长期人类活动的干扰和过度利用，导致植被严重退化，水土流失加剧，山地灾害频繁，干旱化和荒漠化趋势明显。这种趋势若不能遏制，将严重阻碍区域社会经济的快速协调发展，并且威胁成都平原地区的发展和长江中下游地区的生态安全。因而开展干旱河谷生态恢复研究成为解决这些问题的关键。水分匮乏是限制干旱河谷生态恢复的关键因子，在全球气候变化的背景下，干旱胁迫在区域尺度上可能会更加严重，并使干旱河谷的生态环境更加恶化。因此，深入研究干旱河谷乡土植物对干旱胁迫的响应和适应机理，具有非常重要的理论和实践意义。 本论文以岷江上游干旱河谷的三种乡土豆科灌木，白刺花（Sophora davidii）、小马鞍羊蹄甲（Bauhinia faberi var. microphylla）和小雀花（Campylotropics polyantha）理论和实践意义。为研究对象，在人工控制条件下设计了4-5个连续性干旱胁迫处理，系统地研究了灌木幼苗的生长、生物量积累和水分利用效率（WUE）、形态结构和生理过程等对干旱胁迫的反应，揭示了幼苗的干旱适应能力及种间差异。主要研究结论如下： 1) 灌木生长和繁殖对干旱胁迫的反应 在干旱胁迫下，幼苗生长速率显著减小，叶片衰老和脱落比率增大，这些变化随着胁迫强度的增加具有累积效应。叶片比茎对干旱胁迫的反应更敏感。在严重干旱胁迫下，幼苗的有性繁殖被限制，但在中等程度干旱胁迫下，幼苗的有性繁殖能力被提高。 2) 灌木生物量积累及其分配和WUE对干旱胁迫的反应 在干旱胁迫下，灌木各器官的生物量都显著减小，但是生物量的分配侧重于地下部分，使得根茎比在干旱条件下增大。幼苗的耗水量（WU）随着干旱胁迫的增加而显著减少。白刺花和小马鞍羊蹄甲WUE在干旱胁迫下降低；小雀花的WUE在中等干旱胁迫下升高。 3) 灌木叶片结构特征对干旱胁迫反应 白刺花叶片具有较为典型的旱生型结构，而小马鞍羊蹄甲和小雀花则为中生型结构。在1至2年的干旱胁迫下，灌木叶片结构组成未发生本质性的改变，主要是细胞大小的变化。在中等和严重干旱胁迫下，叶肉组织厚度明显减小；并且气孔和表皮细胞面积也显著减小，气孔和表皮细胞密度显著增大；叶肉细胞层数、P/S值、表皮厚度等无显著变化。 4) 灌木对干旱胁迫的生理响应 气体交换参数和叶片相对含水量（RWC）在中等干旱胁迫下发生了明显的改变，而叶绿素荧光参数和光合色素含量在严重干旱胁迫下才发生显著变化。在干旱胁迫下，净光合作用速率（Pn）、气孔导度（gs）和RWC呈下降趋势，而叶片温度（Tl）呈增加趋势，蒸腾速率（Tr）的变化不明显。除了日最大Pn减小以外，干旱胁迫对气体交换参数的日变化无显著影响，但是对光合-光响应曲线有显著的影响，使有效光合时间缩短。在严重干旱胁迫下光系统受到损害而代谢减弱，PSⅡ中心的内禀光能转换效率（Fv/Fm）、量子产量（Yield）、光化学淬灭参数（qP）显著降低，而非光化学淬灭参数（NPQ）明显增加。气孔限制和非气孔限制对Pn的影响与干旱胁迫强度有关。在中度胁迫下，气孔限制起主导作用，在严重胁迫下非气孔限制起主导作用，40% FC水分条件可能是灌木由气孔限制向非气孔限制的转折点。 5) 灌木对干旱胁迫的适应能力及其种间差异 三种灌木对干旱胁迫具有较好的适应能力，即使在20% FC，幼苗未因干旱胁迫III而死亡；80% FC适宜于幼苗生长。白刺花生长速率慢，耗水量较少，具有较强的耐旱和耐贫瘠能力，并具有干旱忍受机制，能够在较干旱的环境中定居和生长。小马鞍羊蹄甲和小雀花，生长快，水分消耗量较大，尤其是小雀花，对干旱胁迫的忍受能力较弱，具有干旱回避机制，因而适宜于在较为湿润的生境中生长。综合分析表明，生长速率较慢的物种抗旱能力较强，其更适宜于作为干旱地区植被恢复物种。 Drought is often a key factor limiting plant establishment, growth and distribution inmany regions of the world. The harsh environmental conditions and long-termanthropogenic disturbance had resulted in habitat destruction in the dry valley ofMinjiang river, southwest China. Recently, it tended to be more severe on the vegetationdegradation, soil erosion and water loss, natural disaster, as well as desertification, whichimpact on regional booming economy and harmonious development, and would be verydangerous to the environmental security in the middle and lower reaches of Yangzi River.Therefore, ecological restoration in the dry valley is one of the vital tasks in China. Waterdeficit is known to affect adversely vegetation restoration in this place. Moreover, in thecontext of climate change, an increased frequency of drought stress might occur at aregional scale in the dry valleys of Minjiang River. The selection of appropriate plantingspecies for vegetation restoration in regard to regional conditions is an important issue atpresent and in further. The research on responses of indigenous species to drought stresscould provide insights into the improvement of the vegetation restoration in the dry valleys of Minjiang River. In this paper, the responses of three indigenous leguminous shrubs, Sophora davidii,Bauhinia faberi var. microphylla and Campylotropics polyantha, to various soil watersupplies were studied in order to assess drought tolerance of seedlings, and to compare interspecific differences in seedlings’ responses to drought stress. The results were as follows: 1 Growth and reproduction of shrubs in response to drought stress Seedling growth reduced significantly while leaf senescence accelerated underdrought stress, the cumulative responses to prolonged drought were found. The capacityfor reproduction was limited by severe drought stress, and improved by moderate droughtstress. Leaf responses were more sensitive than shoot to various water supplies. 2 WUE, biomass production and its partitioning of shrubs in response to drought stress Drought stress reduced significantly the total dry mass and their components ofseedlings, and altered more biomass allocation to root system, showing higher R/S ratiounder drought. Water use (WU) and water-use efficiency (WUE) of both S. davidii and B.faberi var. microphylla declined strongly with drought stress. The WU C. polyantha ofalso declined with drought stress, but WUE improved under moderate drought stress. 3 Anatomical characteristics and ultrastructures of leaves in response to drought stress There were xeromorphic for S. davidii leaves and mesomorphic for B. faberi var.microphylla and C. polyantha at the all water supplies. The foundational changes in leafstructures were not found with drought stress. However, mesophyll thickness, the areas ofstomatal and epidermis reduced slightly while the densities of stomatal and epidermisincreased under severe drought stress. Variations in these parameters could mainly be duoto cell size. Other structures did not displayed significant changes with drought stress. 4 Physiological responses of shrubs to drought stress The gas exchange parameters and leaf relative water content (RWC) were affectedby moderate stress, while chlorophyll fluorescence and chlorophyll content were onlyaffected by severe stress. Drought stress decreased net photosynthesis rate (Pn), stomatalconductance, light-use efficiency and RWC, and increased leaf temperature. Therespiration rates (Tr) were kept within a narrower range than Pn, resulting in aprogressively increased instantaneous water use effiecency (WUEi) under drought stress.Moreover, drought stress also affected the response curve of Pn to RAR, there was adepression light saturation point (Lsat) and maximum Pn (Pnmax) for moderate andsevere stressed seedling. However, diurnal changes of gas exchange parameters did notdiffer among water supplies although maximum daily Pn declined under severe stress.VISevere stress reduced Fv/Fm, Yield and qP while increased NPQ and chlorophyll content.Photosynthetic activity decreased during drought stress period due to stomatal andnon-stomatal limitations. The relative contribution of these limitations was associatedwith the severity of stress. The limitation to Pn was caused mainly by stomatal limitationunder moderate drought stress, and by the predominance of non-stomatal limitation undersevere stress. In this case, 40% FC water supply may be a non-stomatal limitation 5 Interspecific differences in drought tolerance of shrubs Three shrubs exhibited good performance throughout the experiment process, evenif at 20% FC treatment there were no any seedlings died, 80% FC water supply wassuitable for their establishment and growth. S. davidii minimized their water loss byreducing total leaf area and growth rate, as well as maintained higher RWC and Pncompared to the other two species under drought stress, thus they might be more tolerantto the drought stress than the other two species. On the contrary, it was found that C.polyantha and B. faberi var. microphylla had higher water loss because of their stomatalconductance and higher leaf area ratios. They reduced water loss with shedding theirleaves and changing leaf orientation under drought stress. Based on their responses, thestudied species could be categorized into two: (1) S. davidii with a tolerance mechanismin response to drought stress; (2) C. polyantha and B. faberi var. microphylla withdrought avoidance mechanism. These results indicated that slow-growing shrub speciesare better adapted to drought stress than intermediate or fast-growing species in present orpredicted drought conditions. Therefore, selecting rapid-growing species might leavethese seedlings relatively at a risk of extreme drought.

中国沙棘(Hippophae rhamnoides subsp. sinensis)不同种群对干旱胁迫的响应差异与干旱诱导蛋白的分析

沙棘广泛分布于亚欧大陆的温带地区和亚洲亚热带的高海拔地区。沙棘能适应多种生态环境，能耐受多种逆境(如干旱、低温、高温和盐害等)。在中国，沙棘常常被用作植被恢复中的先锋树种而大量栽培。本文以中国沙棘为试验材料，探索沙棘适应干旱机制，以及沙棘对干旱胁迫的适应机制是否存在种群间的差异，同时试图通过分析干旱胁迫下沙棘叶片蛋白质表达变化探索沙棘适应干旱胁迫的分子机理。 对三个分别来自低海拔湿润地区、低海拔干旱地区和高海拔湿润地区的中国沙棘种群进行干旱胁迫处理。干旱胁迫能提高根冠比，比叶面积，降低平均叶面积和总生物量，提高沙棘的抗氧化性酶活性、脯氨酸含量、脱落酸(ABA)含量、降低光合作用，提高长期用水效率。实验中的这两个低海拔种群比高海拔种群抵抗干旱的能力更强,不同的种群采用了不同的策略来耐受干旱胁迫和过氧化胁迫。 在2004 年度的实验中，干旱胁迫处理下，高海拔湿润种群(道孚种群)严重失水，生长也受到更大的抑制，非气孔因素在抑制光合作用方面占支配地位，抗坏血酸含量下降，ABA和脯氨酸含量增加幅度比九寨沟种群的要高，这可能是因为道孚种群严重失水而引起的；而低海拔湿润种群(九寨沟种群)的体内水分状况几乎不受干旱的影响，生长情况也较道孚种群要好。 在2005 年度的试验中，和高海拔湿润地区种群(道孚)相比较，低海拔干旱地区种群(定西)在叶片相对水含量、根冠比、抗氧化酶活性(过氧化氢酶、抗坏血酸过氧化物酶和谷胱甘肽过氧化物酶)、保护性物质(脯氨酸，脱落酸)含量等方面都要高，光能热耗散能力也更强，而且气体交换参数(气孔扩散阻力和胞间CO2浓度等)对干旱也更不敏感。 分析了干旱胁迫下沙棘叶片蛋白质表达的变化。共发现319 个蛋白质，有4 个蛋白在干旱胁迫下消失(Putative ABCtransporter ATP-binding protein 、Hypothetical proteinXP-515578，热激蛋白Hslu219 和一个没得到鉴定的蛋白)，4 个只在干旱胁迫下出现(没命名的蛋白质产物，对甲基苯-丙酮酸双加氧酶，NTrX 和一个没得到鉴定的蛋白)，46 个蛋白质的表达丰度变化显著，包括32 个干旱负调蛋白，14 个干旱正调蛋白(3 个Rubisco 的大亚基、J-type–co-chaperone Hsc20、putative protein DSM3645-2335、putative acyl-COA 脱氢酶、nesprin-2 和两个没有得到鉴定的蛋白质)。这些蛋白质参与了氮代谢调控、抗氧化行物质的合成、脂肪酸β－氧化、核骨架构造、[Fe-S]基团组装、物质跨膜运输、细胞分裂或作为分子伴侣和蛋白质酶起作用。putative ABC transporter ATP-binging protein、NtrX、nesprin-2 和Hslu 是本试验新发现的高等植物蛋白，我们主要从它们的保守结构域或在其他生物中的同源物来猜测它们的功能。实验结果为我们研究植物抗干旱机制提供了新线索和新视野。 Seabuckthorn (Hippophae rhamnoides L.) is widly distributed throughtout the temperatureresiogn of Europe and Asia and sub-tropical plateau zone of Asia. H. rhamnoides can adapatseveral different environments, and can tolerant several envioronmental stresses (e.g, lowtemperature, high temperature, drought and salty). It has been widely used in forest restoration asthe pioneer species in China. In present study, we applied H.rhamnoides subsp. Sinensis asexperimental materials to study its drought-tolerant mechanism, and expected to findpopulational difference in drought-tolerant mechanism that may exist among populations, and tryto get some insight in drought-tolerant mechanism of it at morecular level through analyzing thechange of leaf protein expression. Three populations from high altitude wet zone, low altitude wet zone and low altitude arid znoe,respectively, were applied in our experiment, and were subjected to drought. Drought increasedthe root/shoot ratio(RS), special leaf area, long-term water use efficinency, activity of antioxidantenzymes, proline content and abscisic acid (ABA) content, declined the net photosynthesis rate(A), average leaf area (ALA), total biomass (TB). Both two low altitude populations were moredrought-tolerant than the high altitude population, and different population applied differentstratedgies to tolerant oxidant stress and drought stress. The results of the exprement in 2004 showed that Daofu population was more drought-sensitivethan Jiuzhai population. Under drought conditions, leaf relative water content (RWC) greatlydecreased in Daofu population, but not in Jiuzhai population. The large loss of water in Daofupopulation resulted in a limitation on A mainly caused by non-stomatal factors, severer suppression in growth rate and a significant reduction in ascorbic acid (AsA) content, comparedwith Jiuzhai population. The greater increase in content of ABA and proline in Daofu populationmay be also induced by large loss in water, so that enable plants to cope with sever drought. In the exprement of 2005, drought significantly increased RS, activities of catalase (CAT),peroxidase (POD), glutathione peroxidase (GPX) and ascorbate peroxidase (APX), and alsosignificantly increased ABA and proline contents. On the other hand, compared with Daofupopulation, drought induced larger RS and activities of CAT, GPX and APX, and higher ABAcontent in Dingxi population, whereas gas exchange traits, e.g., stomatal limitation value (LS) andintercellular CO2 concentration (Ci), were less responsive to drought in Dingxi population thanthose in Daofu population. All these factors enable Dingxi population to tolerant drought betterthan Daofu population. The leaf protein profile of seabuchthorn subjected to drought was analyzed. Altogether 319proteins were detected in well-watered sample, four proteins disappeard by drought (putativeABCtransporter ATP-binding protein, hypothetical protein XP-515578, Hslu219and aunidentified protein), four only appeared under drought (a probable nitrogen regulation protein(NtrX), a 4-hydroxyphenylpyruvate dioxygenase , an unnamed protein product and an identified protein), 32 drought down-regulated proteins, and 14 drought up-regulated proteins (nine wereidentified: three large subunits of Rubisco, a hypothetical protein DSM3645-23351, a putativeacyl-COA dehydrogenase, a nesprin-2, a J-type-co-chaperone HSC20 and two unmatchedproteins). These proteins may involve in β-oxidation, cross-membrane transport, cell division,cytoskeleton stabilization, iron-sulfur cluster assembly, nitrogen metabolism regulation andantioxidant substance biosynthesis or function as molecular chaperone or protease. Four proteins(a putative ABC transporter ATP-binging protein, NtrX, nesprin-2, Hslu) were new found in highplants, and their functions were estimated from their conserved domain or their homologues inother organism. Our results provided new clue and new insight for us to study thedrought-tolerant mechanism in plants.

滇杨(Populus yunnanensis)对增强紫外辐射、干旱和喷施脱落酸的生态生理响应

目前，随着全球气候变化的加剧，水分短缺更加明显。在干旱与半干旱地区，水分胁迫是影响植物存活和生长的主要限制因子。同时，随着大气平流层中臭氧浓度的减少，过量的紫外辐射(UV-B)到达地球表面，一些地区的植物不可避免地受到增强UV-B 和水分胁迫的共同作用。文献表明在UV-B 增强的情况下，干旱表现为减弱或增强UV-B 对植物的影响，这与种、品种有一定的相关性。另外，脱落酸(ABA)是近年来研究报道最多的信息调控物质，与植物抗旱性途径有较大的关系，但其对植株抗UV-B 的影响还有待于研究。本论文以滇杨(Populus yunnanensis)为模式植物，从形态和生理方面研究了增强UV-B、干旱和脱落酸对它的影响，并探讨了UV-B 与干旱的互作效应以及喷施脱落酸对植株抗旱性和抗UV-B 能力的影响。主要研究结果如下：1. 增强的UV-B 和干旱胁迫都影响了滇杨的形态生长和生理生化反应。它们都导致了滇杨植株的株高、基茎、整株叶面积、平均叶面积、总生物量和净光合速率的显著降低，使得叶片增厚，过氧化物酶(GPX)活性升高，脯氨酸和花色素苷含量增加，膜脂过氧化程度增大。不同的是干旱显著降低了植株叶片数目，增大了根/冠比(Rs)、细根/总根比(Ft)、提高了内源ABA 含量、碳同位素(δ13C)以及紫外吸收物质含量和超氧化物歧化酶(SOD)的活性，而UV-B 对它们没有影响。干旱与UV-B 的复合作用加剧了任一单独胁迫对植株的抑制，表现为更小的株高、基茎、整株叶面积、平均叶面积、总生物量，更低的光合作用和更高的MDA 含量。而且UV-B 辐射降低了干旱胁迫下生物量分配的可塑性，表现为降低了干旱情况下的Rs 和Ft，ABA 的含量也显著下降，复合胁迫下脯氨酸含量和过氧化氢酶(CAT)的活性比任一单独胁迫时都要低。这些实验结果表明，增强的UV-B 与干旱的复合胁迫加剧了对植株的抑制作用。II2. 干旱情况下同时施加外源ABA 提高了植株的根/冠比、细根/总根比和单位面积叶重，即提高了干旱胁迫下植株对生物量分配的可塑性。而且外源ABA 使干旱胁迫下的长期用水效率、ABA 含量、脯氨酸含量、GPX 活性进一步增加，并有效调节了活性氧代谢的平衡，抑制了受旱植株MDA 的增加。结果表明，外源ABA 的喷施提高了滇杨植株的抗旱性。3. 在增强的UV-B 情况下，外源ABA 加剧了UV-B 对滇杨形态生长的抑制效果，表现为进一步降低了滇杨植株的整株叶面积、平均叶面积、单位面积叶重和总生物量，而且ABA 还降低了UV-B 胁迫下的净光合速率和脯氨酸的含量，增大了MDA 的含量。通过以上的数据我们可以看出，外源ABA 虽然提高了滇杨植株的抗旱性，但却加剧了UV-B 胁迫对植株的抑制作用。Currently, drought is one of the most serious environmental stresses. In arid and semi-aridregions, drought is a major constraint imposed on tree survival and growth. The decrease ofozone layer leads to a significant increase in ultraviolet-B (UV-B, 280-320 nm) radiationreaching the earth surface. In some places, plants suffer both UV-B and water stresssimultaneously. Their combination will increase or decrease the sensitivity of plants to UV-Bstress which lies on the species. On the other hand, abscisic acid (ABA), as a plant homoneand growth regulator, is better for plants resistant to drought stress, but it is uncleared aboutthe relationship between exogenous ABA and supplemental UV-B. In the present study, weemployed Populus yunnanensis Dode as a model species to characterize the growth andecophysiological responses of woody plants to supplemental UV-B, drought and exogenous ABA. The results are as follows:1. Both supplemental UV-B and drought affected the morphological, physiological andbiochemical responses of P. yunnanensis. They decreased the plant height, basal diameter,total leaf area, average leaf area, biomass and photosynthesis, and increased specific leaf mass,the activity of guaiacol peroxidase (GPX), the content of proline, anthocyanins andmalondialdehyde (MDA). However, drought decreased the leaf number and increasedroot/shoot ratio, fine root/total ratio, the activity of superoxide dimutase (SOD) and thecontents of ABA, carbon isotope composition (δ13C), UV-absorbing compounds. Whilesupplemental UV-B had no effects on them. The combination of drought and UV-Baugmented the growth inhibtion acting as further lower plant height and smaller basaldiameter, leaf area, biomass and higher MDA content. And compared with drought stress,root/shoot ratio and fine root/total root ratio decreased under the combination stresses. The photosynthesis, proline content and Catalase (CAT) activity became lower under combinationstresses than that of either stress lonely. According to these results, we suggested that,compared with the effect of stress lonely, the combination of supplemental UV-B and droughtdid not mitigate the harmful effect, but augmented it.2. Under drought conditions, exogenous ABA increased root/shoot ratio, fine root/total rootratio and the specific leaf mass. That was to say exogenous ABA increased plant plasticityunder drought conditions. Also ABA content, proline content, activity of GPX and δ13C wereenhanced further. In addition the enhancement of MDA was restrained. So the resultssuggested that exogenous ABA increased the seedling capacity of resistance to drought.3. Under supplemental UV-B conditions, exogenous ABA augmented the growth restrain ofUV-B to seedlings, which acted as further decreased leaf area, specific leaf mass and biomass.Compared with UV-B stress alone, proline content and photosynthesis were decreased andMDA content was increased under the combination of UV-B and ABA. These resultssuggested that although exogenous ABA increased the seedling capacity of resistance todrought, it augmented the growth restrain of supplemental UV-B to P. yunnanensis.

水分梯度上不同灌木生长对干旱河谷土壤理化和生物学性质的影响

岷江上游干旱河谷区水土流失强烈，地质灾害频繁，生态环境十分脆弱，而土壤条件恶劣（水分不足和养分缺乏）是阻碍该区植被恢复的关键因子，因此研究水分和乡土灌木生长对土壤的影响对该区的生态恢复具有指导意义。本文通过定点模拟实验，选取三种优势豆科灌木为研究对象，分别是白刺花（Sophora davidii）、小马鞍羊蹄甲（Bauhinia faberi var. microphylla）和小雀花（Campylotropics polyantha），设置5 个水分梯度，分别为100%、80%、60%、40%和20%田间持水量（FC），对栽种植物与不种植物下土壤理化性质和酶活性进行测定分析，系统比较和研究了不同水分条件和不同乡土灌木生长对干旱河谷区土壤结构、养分循环、酶活性以及微生物量的影响。主要结果如下：1. 无论生长植物与否，土壤的毛管持水量和毛管孔隙度都随着水分含量的减少而降低，最大持水量、总孔隙度和容重变化不大，相应地，土壤中的非毛管孔隙随含水量的减少而升高。各水分条件下，种植植物的毛管持水量和毛管孔隙度低于无植物生长的土壤，非毛管孔隙度相应地高于无植物土壤。土壤含水量在100%－40% FC 时，三种豆科灌木的毛管持水量和毛管孔隙度存在差异，而20% FC 条件下，三种豆科灌木土壤的物理性质基本相同。2. 水分胁迫影响土壤中养分的矿化和积累，主要表现在降低了水溶性碳和铵态氮的含量，中等程度胁迫时（60% FC）促进了有机碳和硝态氮的富集，对速效钾和有效磷没有明显作用。种植豆科灌木后各水分梯度上都增加了有机碳、铵态氮、速效钾和有效磷的积累。增加程度上三种豆科灌木间有一定差异，对于土壤有机碳总量，种植白刺花和小马鞍羊蹄甲明显高于小雀花，同样的情况还出现在铵态氮和速效钾上，但是对于有效磷，种植小雀花后的增加程度则明显高于白刺花和小马鞍羊蹄甲。种植豆科灌木不仅增加了土壤养分的相对含量，也改变了其在水分梯度上的变化趋势及其变化幅度，这种作用主要体现在碳元素和氮元素上。3. 无植物生长时脲酶活性随水分含量的减少而升高，水分胁迫对磷酸酶和过氧化氢酶的作用不显著，蔗糖酶也保持在相对较高的水平。种植植物后，蔗糖酶、磷酸酶活性与无植物时相比有较大幅度的提高，种植白刺花的脲酶活性也升高，其升高的程度在不同水分含量时不同。种植植物还降低了酶活性在水分梯度上的变幅，使之在水分梯度间的差异显著性降低。脲酶活性在指示土壤性质改变方面是较敏感的指标，其它三种酶在不同植物间的差异不明显。4. 在无植物生长时，中等程度的水分胁迫（60% FC）提高了土壤微生物量碳含量，过高或过低的土壤水分均不利于微生物碳的积累。种植小马鞍羊蹄甲后微生物量碳在水分梯度上的变化趋势与无植物生长时一致，而种植白刺花和小雀花后微生物量碳随着水分含量的减少而降低。不同种类植物的微生物量碳在水分梯度上的变化特征也不同，100% FC 条件下三种植物间没有差异，80%和60% FC 条件下小马鞍羊蹄甲显著高于白刺花和小雀花，40%和20% FC 条件下白刺花和小马鞍羊蹄甲也显著高于小雀花，说明不同种类植物随着干旱胁迫程度的加深微生物量碳的降低幅度不同，在极度干旱时，白刺花和小马鞍羊蹄甲土壤依然保持了较高的微生物活性，而小雀花土壤微生物量则明显下降。The dry valley of the upper reaches of the Minjiang River is seriously degradedmountain ecosystem. It was endangered by extremely soil lost and frequentlygeological disaster. Previous studies showed that short of water and nutrients in soilwas the principal limiting factors of vegetation restoration in this area. The typical soiland three dominant leguminous shrubs Sophora davidii, Bauhinia faberi var.microphylla and Campylotropics polyantha in upper reaches of arid Minjiang Rivervalley were considered as experimental material. Two-month old seedlings of eachspecies were exposed to five water supplies (100%, 80%, 60%, 40% and 20% waterfield capacity (FC)) in a temperature and light-controlled greenhouse. Afterthree-month water treatment, soil physiochemical variables and soil microbialactivities were determined by conventional methods. The main results showed that:1. Soil capillary capacity and capillary porosity decreased along water supplyregimes in all treatments, while saturated water capacity, total porosity and bulkdensity kept in a relatively stable level, as a result, the non-capillary porosity andcapacity increased with decrease of water supply. Compared to non-planted soil, theplant-soil systems had a higher non-capillary porosity and capacity, suggestingappropriate oxygen was present in soil to maintain the living of microorganism. Soilof three type shrub species shared the same capillary capacity and capillary porosityunder 20% FC.2. Water soluble carbon and NH4+-N decreased in response to water stress, whiletotal organic carbon and NO3--N promoted by moderate water stress and inhibited by 100% and 20% FC. Total organic carbon, NH4+-N, rapidly available K and availableP increased after the planting of leguminous shrubs in five water supply regimescompared to non-planted soil. For TOC, NH4+-N and rapidly available K, thepromotion effect was higher in S. davidii and B. faberi var. microphylla than C.polyantha planted soil, while available P displayed the opposite side. The planting ofshrubs also reduced the variance of observed traits along water supply gradients.3. Drought stress increased urease activity in non-planted soil, while insignificantdifferences were observed in phosphatase and catalase activity among five watersupply regimes. The planting of leguminous shrubs facilitated the β-glucosidase andphosphatase activity compared to the non-planted soil. It also reduced the variance ofenzyme activity along water supply gradients. Urease was more sensitive to waterstress than other three enzymes.4. Soil water content significantly affected microbial biomass carbon andCmic:Corg. S. davidii and B. faberi var. microphylla showed more drought toleranceability than C. polyantha, attributing not only to their relatively smaller variance ofmicrobial biomass carbon along soil water supply gradients, but also to the highlevel of microbial activity under severe water stress. S. davidii and B. faberi var.microphylla benefited reproduction of soil microorganism at 60%-80% FC, whilesevere drought limited it due to the competition of water and nutrients between plantand soil microorganism.

遮荫与外源脱落酸喷施对青杨(Populus cathayana Rehd.)不同种群抗旱性的影响

杨树具有分布广、适应性强的特征，在生态环境治理和解决木材短缺方面均占有重要位置。青杨(Populus cathayana Rehd.)是青杨派树种的重要成员之一，也是生长较迅速、易繁殖的重要杨树资源。本研究选取了来自不同气候地区的青杨两种群为材料，采用植物生态学、生理学和生物化学的研究方法，系统地研究了青杨对干旱与遮荫、干旱与外源脱落酸(ABA)喷施的生长、形态、生理和生化响应及种群间差异，研究成果可为我国干旱半干旱地区的造林以及生态恢复提供理论依据和科学指导。主要研究结论如下：1.青杨在干旱胁迫下的适应机制为：生长性状及生物量的分配变化：干旱胁迫下虽然植株生长受抑，株高、基茎及各部分生物量都显著减小，但有相对较多的生物量向根部分配，根/冠比以及细/粗根比增加。青杨对干旱胁迫的光合作用表现为：干旱胁迫降低了青杨的净光合速率、蒸腾速率、气孔导度以及光合氮利用效率，提高了瞬时用水效率。干旱还引起了活性氧的产生，使得膜脂过氧化产物丙二醛(MDA)增加，同时也增强了植物抗氧化酶系统(如超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性的增加)及非酶系统的能力(如抗坏血酸(AsA)含量的增加)。干旱降低了植物叶片的相对含水量，而促进了渗透调节物质(游离脯氨酸及可溶性糖)的积累，增加了植物的渗调能力。干旱下青杨两种群的内源ABA含量显著增加，碳同位素组分(δ13C)也显著提高。这些结果证明植物遭受干旱胁迫后发生一系列的形态、生理和生化响应，这些变化能提高植物在干旱下的存活和生长能力。2.青杨两种群对干旱胁迫反应的种群差异：与来自湿润地区的汉源种群相比，来自干旱地区的乐都种群在干旱条件下生物量向根系分配的可塑性更强，同时具有更强的抗氧化系统能力，所受到活性氧的伤害也更少，并且累积更多的脯胺酸和ABA，具有更高的δ13C。这些都说明了乐都种群对干旱的适应性比汉源种群更强。两种群对干旱的响应差异应归于它们的用水策略的不同：汉源种群来自湿润地区，采用了耗水型的用水策略，抗旱能力较弱；而乐都种群，来自干旱地区，通常采用节水型的用水策略，有更强的抗旱能力。3.遮荫对青杨两种群抗旱性的影响：遮荫对青杨抗旱性的影响决定于遮荫程度的不同，我们的结果表明中度的遮荫可以有效的提高干旱下植物的生长，对干旱胁迫有明显的缓解作用，具体体现在中度遮荫下受旱植物的叶片相对含水量得到提高，使得植物体内水分状况得到了改善；光合速率并未降低，植物光合氮利用效率增加，说明中度的遮荫并未明显限制植物的碳获得；抗氧化酶活性与膜脂过氧化产物MDA含量的同时降低，说明中度遮荫下所受到的活性氧伤害减少；中度遮荫下的ABA及δ13C的变化也不如在全光下变化明显，这也说明中度遮荫缓解了干旱胁迫。但是重度的遮荫却对干旱胁迫有明显的加剧作用，主要表现在重度遮荫降低了植物的光合速率，严重抑制了植物的生长；同时重度遮荫下脯胺酸含量和抗氧化酶活性的急剧下降，导致了植物渗调能力的下降及膜脂过氧化产物MDA的显著升高；重度遮荫还显著降低了内源ABA的累积和δ13C，降低了植物的抗旱能力。此外，青杨两种群在对干旱和遮荫的响应中，也表现出种群差异。汉源种群，来自湿润且年日照辐射较少的地区，表现出相对更强的耐荫性和需水性。而乐都种群，来自干旱且年日照辐射丰富的地区，表现出相对更强的耐旱性和需光性。这说明了植物对环境胁迫的耐受性是其长期适应原生境的结果，并且来自不同气候地区的两种群在面临环境胁迫时会采取不同的生存策略。4. 外源ABA喷施对青杨两种群抗旱性的影响：外源ABA的喷施可以提高两种群的抗旱性，具体表现为外源ABA喷施促进了青杨根系的生长，显著提高了干旱下植物的根/冠比和细/粗根比，减少了比叶面积；在生理生化方面，外源ABA降低了干旱下植物叶片的气孔导度，降低了蒸腾速率和净光合速率，但提高了瞬时用水效率，提高了叶片的相对含水量，增加了干旱下植物的保水能力。外源ABA进一步增加了干旱下植物内源ABA的积累，促进了植物渗调物质如脯胺酸和可溶性糖的积累，增加了抗氧化酶系统(如SOD、APX、CAT)的活性和非酶系统AsA的含量，降低了活性氧(如超氧阴离子(O2和过氧化氢(H2O2))对植株的伤害。此外，外源ABA还进一步提高了干旱下植物的δ13C，提高了植物的长期用水效率，由此提高了植物的抗旱能力。另一方面，两种群对外源ABA和干旱的响应也有所差别。来自湿润地区的汉源种群，对干旱较为敏感，所受干旱的影响也较大，而外源ABA的喷施对汉源种群抗旱性的提高作用也更为突出。乐都种群，由于其长期适应干旱地区的生长，本身已具有较强的抗旱能力，因此外源ABA喷施对其抗旱性的提高不如对汉源种群的效果明显。由此我们可以得出对于一些抗性弱或干旱敏感的物种或者种群，可以采用外施ABA的方法来提高其抗性。Poplars play an important role in lumber supply, and are important component ofecosystems due to their wide distribution and well adaptation. Populus cathayana Rehd.,which belongs to Populus Sect. Tacamahaca Spach, is one of the most important resources ofpoplars for its fast growth and reproductive. In this study, different populations of P.cathayana were used as experiment material to investigate the adaptability to drought stressand population differences in adaptability, and the effects of shade and exogenous abscisicacid (ABA) application on the drought tolerance. Our results could provide a strongtheoretical evidence and scientific direction for the afforestation, and rehabilitation ofecosystem in the arid and semi-arid area, and provide a strong evidence for adaptivedifferentiation of different populations, and so may be used as criteria for species selectionand tree improvement. The results are as follows:1. A large set of parallel response to drought stress: Drought stress caused pronouncedinhibition of the growth and increased relatively dry matter allocation into the root. For thetwo populations, the shoot height, basal diameter and total biomass were decreased but theroot/shoot ratio and fine root/coarse root ratio were increased under drought conditions；Drought stress caused pronounced inhibition of photosynthesis, decreased the stomatalconductance, transpiration rate, and photosynthetic nitrogen-use efficiency (PNUE) butincreased the instantaneous water use efficiency. Drought significantly improved the levels ofreactive oxygen species and malondialdehyde (MDA) and to induce the entire set ofantioxidative systems including the increase of activities of superoxide dismutase (SOD),ascorbate peroxidase (APX), catalase (CAT) and ascorbate (AsA) content. Drought decreased the leaf relative water content (RWC) but improved the capability of osmotic adjustmentindicated by the higher proline accumulation. Drought also increased the ABA content andcarbon isotope composition (δ13C), which indicating the long period water use efficiency wasimproved under drought. These results demonstrate that there are a large set of parallelchanges in the morphological, physiological and biochemical responses when plants areexposed to drought stress; these changes may enhance the capability of plants to survive andgrow during drought periods.2. Difference in adaptation to drought stress between contrasting populations of P.cathayana: Compared with the Hanyuan population (wet climate), the Ledu population (dryclimate) showed higher root/shoot ratio and water use efficiency, exhibited higherantioxidative systems capability thus resulting in less oxidative damage, accumulated moreABA and free proline content under drought conditions. The results suggested that there weredifferent water-use strategies between the two populations. The Ledu population, whichcomes from dry climate region, with higher drought tolerance, may employ a conservativewater-use strategy, whereas the Hanyuan population, which comes from wet climate, withlower drought tolerance, may employ a prodigal water-use strategy. These variations indrought responses may be used as criteria for species selection and tree improvement.3. The effects of shade on the drought tolerance: The reduction in the availability of lightand water affected the morphological and physiological responses of the two P. cathayanapopulations. In addition, the light environment modified the growth responses of P.cathayana seedlings to varying water environments in different ways depending upon theintensity of the light levels considered. There is an apparent alleviation to drought effects bymoderate shade in P. cathayana seedlings, as indicated by the higher leaf RWC, and unchanged net photosynthesis and PNUE, as well as by the lower antioxditative enzymeactivity, MDA, ABA and δ13C levels, which implied moderate shade did not significantlylimited the carbon acquisition or inhibited the plant growth, but ameliorated the detrimentaleffects of drought. On the other hand, an apparent aggravation to drought effects by severeshade was also observed, as indicated by the pronounced decrease of plant growth and net photosynthesis, the lower total biomass, ABA level, δ13C, free proline content andantioxditative enzyme activity and higher MDA accumulation. By contrast, the twopopulations showed different responses to shade and drought. The Hanyuan population,which comes from a riparian basin having a relatively wet climate and less annual solarradiation, is more sensitive to drought but more tolerant to shade. The Ledu population, whichcomes from a mountainous plateau with less rainfall and with more annual solar radiation, ismore tolerant to drought but more sensitive to shade. The results demonstrated that theendurance of plants to stress is a result of long-term evolution and adaptation to theenvironment, as suggested by the different strategies employed by the P. cathayanapopulations originating from contrasting habitats when they were exposed to drought andshade.4. The effects of exogenous ABA application on the drought tolerance: For bothpopulations under drought conditions tested, exogenous ABA application significantlyimproved the root/shoot ratio, fine root/coarse root ratio, and decreased the specifical leaf area.On the physiological and biochemical traits, exogenous ABA application significantlydecreased stomatal conductance, transpiration rate and net photosythesis but increased theinstance water use efficiency and leaf RWC. On the other hand, exogenous ABA applicationsignificantly increased endogenous ABA, proline, solube sugar and AsA content, as well asSOD, APX and CAT activities, thus reduced the damage of reactive oxygen species. Moreover,the long period water use efficiency as indicated by δ13C was also improved by exogenousABA application. In additionally, there was different responsive between the two populationsto drought and exogenous ABA application. The Hanyuan population, which comes from wetclimate region, is more sensitive to drought, and the effect of exogenous ABA is moreobviously than that in the Ledu population, which comes from dry climate region and is moredrought-responsive. Therefore, we can use exogenous ABA application to improve theresistance of plants, especially for the drought- sensitive species or populations.

青杨(Populus cathayana Rehd.)雌雄植株对干旱胁迫的生理生态响应差异

随着全球气候变暖和温室效应加剧，干旱和荒漠化成为威胁人类生存和发展的主要 灾害，许多被子植物对干旱胁迫的生理、生态和生化响应已逐步得以报道，但很少有开 展干旱胁迫对雌雄异株植物的影响方面的研究。由于这类植物在长期进化过程中已经在 生长、性比、生殖格局、空间分布、资源配置和生物量分配等方面形成了明显的性别差 异，因此，干旱胁迫必将对其雌雄植株产生不同的生理生态影响。本研究以青杨为模式 植物，采用植物生态、生理及生物化学等研究方法，系统研究青杨雌雄植株在常温、增 温以及喷施外源脱落酸的条件下对干旱胁迫的响应，揭示其在生长形态、生物量分配、 光合作用、用水效率和生理生化等方面的性别间差异。主要研究结果如下： 1. 青杨雌雄植株对干旱胁迫的综合响应。 与较好水分条件相比，干旱胁迫显著降低了青杨雌雄植株的光合作用和生长发育， 影响了许多生理生化过程，并导致雌雄植株在生长发育、气体交换、用水效率、膜脂抗 氧化和抗氧化系统酶活性方面表现出显著的性别间差异。在较好水分条件下，雌雄植株 之间在株高、基径、生物量、净光合速率、蒸腾速率、用水效率以及丙二醛、脱落酸和 游离脯氨酸等生化物质含量方面均无显著差异。但在干旱胁迫下，雄株在生长发育、气 体交换、水分利用效率、膜脂过氧化保护和抗氧化系统酶活性方面均显著高于雌株，表 现出比雌株更高的株高、基径、叶面积、总叶片数、总生物量、总色素含量、类胡萝卜 素含量、净光合速率、蒸腾速率、羧化效率、光系统II最大光化学效率、内在水分利用 效率、碳同位素组分、过氧化氢酶和过氧化物酶活性等，而在CO2补偿点、比叶面积、 叶绿素a/b、丙二醛、脱落酸和超氧化物歧化酶活性等指标上显著低于雌株。与雌株相比， 雄株表现出更高的干旱胁迫适应能力，而雌株的生长发育和生理生化过程更易遭受干旱 胁迫的影响。 2. 干旱胁迫下的青杨雌雄植株对增温处理的综合响应 与环境温度相比，增温在干旱胁迫前后均显著促进了雌雄植株的生长发育、气体交 换，降低水分利用效率，影响生化物质含量，并促使青杨雌雄植株之间在干旱胁迫下表 现出显著的差异。在较好水分条件下，增温导致雌株的株高、基径、叶面积、总叶片数、 总生物量和超氧化物歧化酶活性显著高于雄株，而用水效率、丙二醛、脱落酸和游离脯 氨酸、抗坏血酸过氧化物酶和过氧化物酶活性低于雄株。在干旱胁迫下，增温将导致雄 株的株高、基径、叶面积、总生物量、净光合速率、蒸腾速率、气孔导度、总色素含量、 相对含水量、过氧化氢酶和抗坏血酸过氧化物酶活性等显著高于雌株，而光系统II 最大 光化学效率、内在水分利用效率、碳同位素组分、丙二醛、脱落酸、游离脯氨酸和超氧 化物歧化酶活性显著低于雌株。与雄株相比，水分较好条件下的增温有利于促进雌株的 生长发育，并在生理生态特征上优于雄株。而干旱胁迫下的增温则加剧了水分胁迫强度， 致使雌株的生长发育遭受比雄株更多的负面影响。 3. 干旱胁迫下的青杨雌雄植株对喷施外源脱落酸处理的综合响应 与对照相比，在干旱胁迫下喷施外源脱落酸可显著增加青杨雌雄植株的生长发育、 气体交换、降低水分利用效率，影响了生化物质含量，并导致青杨雌雄植株之间在干旱 胁迫下表现出显著的生理生态差异。在干旱胁迫下，喷施外源脱落酸致使雌株的株高、 叶面积、叶干重、细根干重、总生物量、净光合速率、蒸腾速率、气孔导度、光系统II 最大光化学效率、非光化学淬灭系数、相对含水量、总光合色素、类胡萝卜素、脱落酸、 超氧化物歧化酶和过氧化物酶活性的增加量显著高于雄株，而根重比、根冠比、细根/ 总根、比叶面积、内在水分利用效率、碳同位素组分、丙二醛、脯氨酸、过氧化氢酶和 抗坏血酸过氧化物酶活性等指标的减少量上显著低于雄株。与对照相比，干旱胁迫下的 喷施外源脱落酸则一定程度能减缓植株遭受胁迫的压力，促进植株生长和气体交换，减 少了植株体内的过剩自由基数量，并促使雌株的生长发育和光合能力显著提高，增强其 抗干旱胁迫能力。 With development of global warming and greenhouse effect, drought and desertification have been became main natural disasteres in resent years. Studies on ecophysiological responses of most angiosperm species to environmental stress have been reported, but little is known about dioecious plant responses to drought stress. Since significant differences on growth, survival, reproductive patterns, spatial distribution, as well as resource allocation between males and females of dioecious plant have been formed during evolutionary process, sexual different ecophysiological responses should be caused by drought stress. In this experiment, Populus cathayana Rehd. was used as model plant to study the sex-related responses to drought by using the ecological, physiological and biochemical methods under normal atmospheric temperature, elevated temperatures and exogenous abscisic acid (ABA) application treatment respectively, and to expose the sexual differences in growth, biomass allocation, photosynthesis, water use efficiency and some biochemical material contents in the males and females of dioecious plant. The results are follows: 1. A large set of parallel responses of males and females of P. cathayana to drought stress Compared with well-watered treatment, drought significantly decreased growth and photosynthesis of P. cathayana individuals, affected some physiological and biochemical processes, and induced males and females to exhibit obvious sexual differences in growth, gas exchange, water use efficiency, lipid peroxidation protection and antioxidant defenses enzyme system. Under well-watered treatment, there were no significant sexual differences in height growth (HG), basal diameter (BD), dry matter accumulation (DMA), net photosynthesis rate (A), transpiration (E), water use efficiency (WUE), and malondialdehyde (MDA), abscisic acid (ABA) and praline (Pro). However, under drought stress, males were found to exhibit higher HG, BD, leaf area (LA), total leaf number (TLA), DMA, total chlorophyll contents (TC), carotenoids content (Caro), A, E, carboxylation efficiency (CE), the maximum efficiency of PSII (Fv/Fm), intrinsic water use efficiency (WUE ), carbon isotope composition (δ13C), catalase (CAT), peroxidase (POD) and lower CO2 compensation point (Γ), specific leaf area (SLA), chlorophyll a/b ratio (Chla/Chlb), MDA, ABA and superoxide dismutase (SOD) than females. The results suggest that males possess greater drought resistance than do females and females suffer more negative effect on growth and development, physiological and biochemical processes than males under drought stress. 2. A large set of parallel responses of drought-stressed males and females of P. cathayana to elevated temperatures Compared with environmental temperature, elevated temperature treatment significant increased growth and gas exchange, decreased water use efficiency, changed some biochemical material contents of P. cathayana individuals, and induced males and females to exhibit obvious differences under drought stress. Under good water condition, elevated temperature treatment caused females to show significant higher HG, BD, LA, TLN, DMA, SOD activity, and great lower WUE, MDA, ABA, Pro, ascorbate peroxidase (APX) and POD than do males. On contrary, under drought condition, elevated temperature treatment induced males to exhibit higher HG, BD, LA, DMA, A, E, stomatal conductance (gs), relative water content (RWC), CAT, APX activity but lower Fv/Fm, WUE, δ13C, MDA, ABA, Pro, SOD activity than do females. The results suggest that females will benefit from elevating temperature under good water condition by possessing better ecophysiological processes than that of males, but will suffer from greater negative effects than do males when grown under drought stress with elevated temperature treatment. 3. A large set of parallel responses of drought-stressed males and females of P. cathayana to exogenous ABA application Compared with controls, exogenous ABA application under drought greatly increased growth and gas exchange, decreased water use efficiency, changed some biochemical material contents in P. cathayana individuals, and induced males and females to exhibit obvious sexual differences under drought. Under drought stress, exogenous ABA application induced females to exhibit more increases in HG, LA, leaf weight (LW), fine root weight (FRW), DMA, A, E, g, Fv/Fm, non-photochemical quenching coefficient (qN), RWC, TC, Caro, ABA, SOD, POD s activity than males, but to show lower decreases in root/weight ratio (RWR), root mass/foliage area ratio (RF), fine root/total root ratio (FT), SLA, WUE, δ13C, MDA, Pro, CAT, APX than males. The results suggest that exogenous ABA application under drought stress will eliminate negative damages caused by drought stress at a certain extent，promote the growth and gas exchange of plant and decrease the number of superfluous 1O2 in plant cells of males and females of P. cathayana. Furthermore, exogenous ABA application promoted more drought resistance in females than in males by increasing more growth and photosynthetic capacity in females under drought stress.

干旱胁迫与施N条件下白刺花（Sophora davidii）幼苗生长及其适应机制

干旱环境常常由于多变的降水事件和贫瘠土壤的综合作用，表现出较低的生产力和较低的植被覆盖度。全球性的气候变暖和人类干扰必将使得干旱地区缺水现状越来越严竣。贫瘠土壤环境中已经很低的有效养分含量也将会随着干旱的扩大而越来越低。干旱与半干旱系统中不断加剧的水分与养分的缺失将严重限制植物的生长和植被的更新，必然会使得已经恶化的环境恶化速率的加快、恶化范围的加大。如何抑制这种趋势，逐步改善已经恶化的环境是现在和将来干旱系统管理者面临的主要关键问题。了解干旱系统本土植物对未来气候变化的适应机制，不仅是植物生态学研究的重要内容，也对人为调节干旱环境，改善干旱系统植被条件，提高植被覆盖度具有重要的实践意义。 本研究以干旱河谷优势灌木白刺花（Sophora davidii）为研究对象，通过两年大棚水分和施N控制实验和一个生长季野外施N半控制实验，从植物生长－生理－资源利用以及植物生长土壤环境特征入手，系统的研究了白刺花幼苗生长特性对干旱胁迫和施N的响应与适应机制，并试图探讨施N是否可调节干旱系统土壤环境，人工促进干旱条件下幼苗定居，最终贡献于促进植被更新实践。初步研究结论如下： 1）白刺花幼苗生长、生物量积累与分配以及水分利用效率对干旱胁迫和施N处理的适应白刺花幼苗株高、基径、叶片数目、叶面积、根长、生物量生产、相对含水量和水分利用效率随着干旱胁迫程度的增加而明显降低，但地下部分生物量比例和R/S随着干旱胁迫程度的增加而增加。轻度施N处理下幼苗株高、基径、叶片数目、叶片面积和生物量生产有所增加。但重度施N处理下这些生长指标表现出微弱甚至降低的趋势。严重干旱胁迫条件下，幼苗叶面积率、R/S、相对含水量和水分利用效率也以轻度施N处理为最高。 2）白刺花幼苗叶片光合生理特征对干旱胁迫和施N处理的适应叶片光合色素含量和叶片光合效率随着干旱胁迫程度的增加而显著降低，并且PS2系统在干旱胁迫条件下表现出一定程度的光损害。但是比叶面积随着干旱胁迫程度的增加而增加。在相对较好水分条件下幼苗净光合速率的降低可能是因为气孔限制作用，而严重干旱胁迫条件下非气孔限制可能是导致幼苗叶片光合速率下降的主要原因。叶片叶绿素含量、潜在光合能力、羧化效率、光合效率以及RUBP再生能力等在施N处理下得到提高，并因而改善干旱胁迫条件下光合能力和效率。虽然各荧光参数对施N处理并无显著的反应，但是干旱胁迫条件下qN和Fv/Fm在轻度施N处理下维持相对较高的水平，而两年连续处理后在严重干旱胁迫条件下幼苗叶片光合效率受到重度施N处理的抑制，并且Fv/Fm和qN也在重度施N处理下降低。 3）白刺花幼苗C、N和P积累以及N、P利用效率对干旱胁迫和施N处理的适应白刺花幼苗C、N和P的积累，P利用效率以及N和P吸收效率随干旱胁迫程度的增加而显著降低，C、N和P的分配格局也随之改变。在相同水分处理下，C、N和P的积累量、P利用效率以及N和P吸收效率在轻度施N处理下表现为较高的水平。然而，C、N和P的积累量和P利用效率在重度施N处理下不仅没有表现出显著的正效应，而且有降低的趋势。另外，在相同水分条件下白刺花幼苗N利用效率随着施N强度的增加而降低。 4）白刺花幼苗生长土壤化学与微生物特性对干旱胁迫和施N的适应白刺花幼苗生长土壤有机C、有效N和P含量也随干旱胁迫程度的增加而明显降低。干旱胁迫条件下土壤C/N、C/P、转化酶、脲酶和碱性磷酸酶活性的降低可能表明较低的N和P矿化速率。尽管微生物生物量C、N和P对一个生长季干旱胁迫处理无显著反应，但微生物生物量C和N在两年连续干旱胁迫后显著降低。土壤有机C和有效P含量在轻度施N处理下大于重度施N处理，但是有效N含量随着施N强度的增加而增加。微生物生物量C和N、碱性磷酸酶和转化酶活性也在轻度施N处理下有所增加。但是碱性磷酸酶活性在重度施N处理下降低。 5）野外条件下白刺花幼苗生长特征及生长土壤生化特性对施N的适应植物生长、生物生产量、C的固定、N、P等资源的吸收和积累、其它受限资源的利用效率（如P）在轻度施N处理下均有所增加，但N利用效率有所降低。幼苗生物生产量及C、N和P等资源的分配格局在轻度施N处理下也没有明显的改变。白刺花幼苗叶片数目、生物生产量和C、N、P的积累量在重度施N处理下虽然也相对于对照有所增加，但幼苗根系长度显著降低。生物量及资源（生物量、C、N、P）在重度施N处理下较多地分配给地上部分（主要是叶片）。另外，土壤有机C、全N和有效N含量随外源施N的增加而显著增加，土壤pH随之降低，但土壤全P含量并无显著反应。其中有机C含量和有效P含量以轻度施N处理最高。微生物生物量C、N和P在轻度施N处理下也显著增加，而微生物生物量C在重度施N处理下显著降低。同时，转化酶、脲酶、碱性磷酸酶和中性磷酸酶活性在施N处理下也明显的提高，但酸性磷酸酶和过氧化氢酶活性显著降低，其中碱性磷酸酶和中性磷酸酶活性以轻度施N处理最高。 综合分析表明，干旱河谷水分和N严重限制了白刺花幼苗的生长。施N不能完全改变干旱胁迫对白刺花幼苗的抑制的作用，但是由于施N增加土壤N有效性，改善土壤一系列生物与化学过程，幼苗的生长特性也对施N表现出强烈的反应，表现为植物结构与资源分配格局的改善，植物叶片光合能力与效率的提高，植物生长以及利用其他受限资源（如水分和P）的效率的增加，致使植物自身生长及其生长环境在干旱环境下得到改善。但是过度施N不仅不能起到改善干旱胁迫下植物生长环境、促进植物生长的作用，反而在土壤过程以及植物生长过程中加重干旱胁迫对植物的伤害。因此，建议在采用白刺花作为先锋种改善干旱河谷系统环境的实践中，可适当施加N以改善土壤环境，调节植物利用与分配资源的效率，促进植物定居，得到人工促进种群更新的目的。但在实践过程中也要避免过度施N。 Arid regions of the world are generally noted for their low primary productivity which is due to a combination of low, unpredictable water supply and low soil nutrient concentrations. The most serious effects of global climate change and human disturbances may well be those which related to increasing drought since drought stress has already been the principal constraint in plant growth. The decline in total rainfall and/or soil water availability expected for the next decades may turn out to be even more drastic under future warmer conditions. Nevertheless, water deficit is not the only limiting factor in arid and semiarid environments. Soils often suffer from nutrient (especially N and P) deficiencies in these ecosystems, which can also be worsened by climate change. How to improve the poor soil quality and enhance the vegetation coverage is always the problem facing ecosystem managers. The adaptive mechanisms of native plant to future climate change is always the focus in plant ecology, it also plays important roles in improving vegetation coverage by manual controlled programmes. Sophora davidii is a native perennial shrub of arid valleys, which is often predominant on eroded slopes and plays a vital role in retaining ecological stability in this region. It has been found that S. davidii was better adapted to dry environment than other shrubs, prompting its use for re-vegetation of arid lands. A two-years greenhouse experiment and a field experiment were conducted in order to understand the adaptation responses of Sophora davidii seedlings to different water and N conditions, and further explore if additional N supply as a modified role could enhance the adaptation ability of S. davidii seedlings to dry and infertile environment. Two-month old seedlings were subjected to a completely randome design with three water (80%, 40% and 20% water field capacity (FC)) and three N supply (N0: 0, Nl: 92 and Nh: 184 mg N kg-1 soil) regimes. Field experiment was arranged only by three N supplies in the dry valley. 1) The growth, biomass partitioning and water-use efficiency of Sophora davidii seedlings in respond to drought stress and N supply Seedlings height, basal diameter, leaf number, leaf area, root length, biomass production, relative water content (RWC) and WUE were decreased with increase of drought stress. An increase in below-ground biomass was observed indicating a higher root/shoot ratio (R/S) under drought stress conditions. Low N supply increased seedlings height, basal diameter, leaf number, leaf area, and biomass production, but decreased root length. In contrast, these growth characteristics showed little or negative effect to high N supply treatment. Leaf percentages increased with increase of N supply, but fine root percentages decreased. In addition, Low N supply rather than the other two N treatments increased leaf area ratio (LAR), leaf/fine root mass ratio (L/FR), R/S and RWC under severe drought stress (20%FC), even though these parameters could increase with the high N supply treatment under well-watered condition (80%FC). Moreover, Low N supply also increased WUE under three water conditions, but high N supply had little effect on WUE under drought stress conditions (40%FC and 20%FC). 2) Leaf gas exchange and fluorescence parameters of Sophora davidii seedlings in respond to drought stress and N supply Leaf area (LA), photosynthetic pigment contents, and photosynthetic efficiency were decreased with increase of drought stress, but specific leaf area (SLA) increased. Photodamage in photosystem 2 (PS2) was also observed under drought stress condition. The decreased net photosynthetic rate (PN) under relative well-watered water conditions might result from stomatal limitations, but the decreased PN under other hand, photosynthetic capacity by increasing LA, photosynthetic chlorophyll contents, Pnmax, CE, Jmax were increased with increase N supply, and photosynthetic efficiency was improved with N supply treatment under water deficit. Although N supply did a little in alleviating photodamages to PS2 caused by drought stress, low N supply enhanced qN and kept relative high Fv/Fm under drought stress condition. However, high N supply inhibited leaf photosynthetic efficiency, and declined Fv/Fm and qN under severe drought stress condition after two year continues drought stress and N supply. 3) Carbon accumulation, nitrogen and phosphorus use efficiency of Sophora davidii seedlings in respond to drought stress and N supply C, N and P accumulation, NUE , N and P uptake efficiency (NUtE and NUtE ) P N P were decreased with increase of drought stress regardless of N supply. On the other hand, the S. davidii seedlings exhibited strong responses to N supply, but the responses were inconsistent with the various N supply levels. Low N supply rather than the other two N treatments increased C, N and P accumulation, improved NUEP, NUtE and NUtE under corresponding water condition. In contrast, high N supply N P did few even depressed effects on C, N and P accumulation, and NUEP, although NUtEN and NUtEP could increase with high N supply under corresponding water conditions. Even so, a decrease of NUEN was observed with increase of N supply under corresponding water conditions. 4) Soil microbial and chemical characters in respond to drought stress and N supply The content of soil organic C, available N and P were decreased with increase of drought stress. Decreases in C/N and C/P, and invertase, urea and alkaline phosphatase activity were also observed under drought stress conditions, indicating a lower N and P mineralization rate. Although microbial biomass C, N and P showed slight responses to drought stress after one growth period treatment, microbial biomass C and N were also decreased with increase of drought stress after two year continuous treatment. The content of soil organic C and available P showed the stronger positive responses to low N supply than which to high N supply, although than the other two N treatments increased microbial biomass N and invertase activity under severe drought stress condition, even though invertase activity could increase with high N supply treatment under relative well-water conditions. Moreover, low N supply treatment also increased C/P and alkaline phosphatase activity which might result from higher P mineralization, but high N supply did negative effects on alkaline phosphatase activity. 5) The growth characteristics of Sophora davidii seedlings and soil microbial and chemical characters in respond to N supply under field condition Low N supply facilitated seedlings growth by increasing leaf number, basal diameter, root length, biomass production, C, N and P accumulation and absorption, and enhancing the use efficiency of other limited resources as P. Compared to control, however, low N supply did little effect on altering biomass, C, N and P portioning in seedlings components. On the contrary, high N supply treatment also increased leaf number, biomass and C, N and P accumulation relative to control, but significantly decreased root length, and altered more biomass and resources to above-ground, which strongly reduced the ability of absorbing water under drought condition, and thus which might deep the drought stress. In addition, N supply increased soil C, N and available N content, but declined pH and showed little effects on P content. Low N supply showed higher values of soil C and available P content. Low N supply also increased microbial biomass C, N and P, although high N supply decreased microbial biomass C. N supply significantly enhanced soil invertase, urea, alkaline and neutral phosphratase activity, while declined acid phosphratase and catalase activity. Low N supply exhibited higher alkaline and neutral phosphratase activity compared to the others. The results from this study indicated that both drought and N limited the growth of S. davidii seedlings and their biomass production. Regardless of N supply levels, drought stress dramatically reduced the seedlings growth and biomass production. Although plant growth parameters, including basal diameter, height, leaf number, and biomass and their components were observed to be positive responses to low N supply, N supply alone can not alter the diminishing tendency which is caused by drought. available N content increased with increase N supply. In addition, low N supply rather These findings imply that drought played a primary limitation role and N was only the secondary. Even so, appropriate N supply was seemed to enhance the ability that S. davidii seedlings adapted to the xeric and infertile environment by improving soil processes, stimulating plant growth, increasing recourses accumulation, enhancing use efficiency of other limited resources, and balancing biomass and resources partitioning. Appropriate N supply, therefore, would be recommended to improve S. davidii seedling establishment in this region, but excess N supply should be avoided.

青杨组(Populus Section Tacamahaca Spach)不同种对非生物胁迫的响应差异

土壤是人类赖以生存的自然环境和农业生产的重要资源，目前土壤受到干旱和盐胁迫的危害越来越严重。杨树具有适应性强、生长快和丰产等特性，本论文以青杨组杨树为模式植物，研究杨树对土壤干旱和盐胁迫的生态生理及蛋白质组学反应，研究成果可为我国干旱半干旱地区营造人工林、防止沙漠化提供理论依据，也为恢复与重建盐污染地区退化生态系统提供科学指导。主要研究结果如下： 1 青杨不同种对逐步干旱胁迫的响应差异 将来自喜马拉雅山东缘高海拔的康定杨和低海拔的青杨枝条扦插在温室中，用来检测它们对逐步干旱胁迫的响应。研究结果表明来自不同海拔的杨树对逐步干旱胁迫的适应性反应是不一样的。株高、叶片发育、叶片相对含水量、丙二醛、过氧化氢等指标的显著性变化在青杨中比在康定杨中来得早些，而且随着干旱胁迫程度的增加，这些参数的变化越来越明显，尤其是当青杨受到严重干旱胁迫的时候；而可溶性蛋白、可溶性糖、游离脯氨酸、抗氧化酶活力变化在康定杨中来得早一些。与青杨相比，在干旱胁迫下，康定杨仍能保持较好的植株生长和叶片发育；康定杨也能在逐步干旱条件下积累更多的可溶性蛋白、可溶性糖、游离脯氨酸及抗氧化酶活力，但是在丙二醛和过氧化氢含量方面增加的更少些。而且，我们的研究结果表明高海拔的康定杨有更强的耐干旱能力，杨树对干旱胁迫的适应能力与干旱发生的速度、强度、持续时间及两种杨树的海拔有关。 2 干旱胁迫下青杨不同种的蛋白质组学分析 来自青杨和康定杨雌株的枝条扦插在温室中，用来研究它们对干旱胁迫的蛋白质组学反应。采用TCA-丙酮/酚提取法提取总蛋白，并进行双向电泳分析。在每个处理的重复图像中都能检测到1,000 个以上的蛋白点。在青杨中有58 个蛋白在干旱处理后发生显著变化，其中22 个蛋白通过肽指纹图谱成功鉴定。康定杨中有69 个蛋白的表达量发生了显著变化，其中有25 个蛋白通过肽指纹图谱成功鉴定。这些被鉴定的蛋白主要参与了光合作用、氧化还原平衡、信号传导、能量代谢、蛋白质合成等过程。尽管被鉴定的蛋白只占叶片总蛋白的很少一部分，但这些被鉴定的干旱响应蛋白可能对维持植株内部平衡方面有重要作用。 3 青杨的盐胁迫响应 青杨植株分别用 0、50 和100 mM NaCl 溶液进行处理。叶片相对含水量、叶绿素a、b 含量、CO2 同化速率和气孔导度的降低表明叶绿体受到了盐胁迫的影响。过氧化氢、丙二醛含量及电导率的升高表明细胞受到了伤害。可溶性糖、游离脯氨酸含量及抗氧化酶含量的上升增加了植株耐盐胁迫的能力。在每个处理的重复图像中都能检测到1,000 个以上的蛋白点。其中有38 个盐响应蛋白被成功鉴定，有16 个蛋白(点4、10、11、14、15、21、24、26、27、28、33、34、35、36、37 和38)出现在盐胁迫的植株中；3 个蛋白(点10、11 和35)只出现在重度盐胁迫处理中；而1 个蛋白(点1)只出现在对照处理中。2 个蛋白(点1 和2)表达量下降，其余蛋白点表达量都增加。被鉴定的蛋白一部分参与了生理生化反应，而另一部分则在信号传导、蛋白质合成等方面有重要作用。盐胁迫下的生理生化变化及蛋白质组学的联合研究有利于青杨对盐胁迫的适应性分析。 Soil is the indispensable environment for human survival and important resource for agriculture development. Nowadays soil is threatened by drought stress and salt stress. Poplars (Populus spp.) possess some characters such as strong acclimilation, fast growth and great production of biomass. In this study, different species of Populus section Tacamahaca spach were used as model plants to investigate the ecophysiological and proteomic responses to drought stress and salt stress. Our results can provide theoretical evidence for the afforestation and prevention of desertification in the arid and semi-arid areas, and also can supply scientific direction for the reconstruction and rehalibitation of ecosystems contaminated by salinity. The results are as follows: 1 Adaptive responses to progressive drought stress in two contrasting poplar species originating from different altitudes Cuttings of Populus kangdingensis C. Wang et Tung and Populus cathayana Rehd., originating from high and low altitudes in the eastern Himalaya, respectively, were examined during one growing season in a greenhouse to determine the effects of progressive drought stress. The results manifested that the adaptive responses to progressive drought stress were different in these two species from different altitudes. Significant changes in height increment, leaf development, relative water content (RWC), malondialdehyde (MDA) and hydrogen peroxide (H2O2) appeared earlier in P. cathayana than in P. kangdingensis, whereas changes in soluble protein, soluble sugar, free proline and antioxidant enzymes appeared earlier in P. kangdingensis. In addition, changes in these parameters became more and more significant when the drought stress progressed, especially under severe drought stress in P. cathayana. Compared with P. cathayana, P. kangdingensis was able to maintain a superior height increase and leaf development under drought stress. Also, P. kangdingensis possessed greater increments in soluble protein, soluble sugar, free proline and antioxidant enzymes, but lower increments in MDA and H2O2 than did P. cathayana when the cuttings were exposed to progressive drought stress. Our results suggest that P. kangdingensis originating from the high altitude has a better drought tolerance than does P. cathayana originating from the low altitude. Furthermore, this study manifested that acclimation to drought stress are related the rapidity, severity, duration of the drought event and the altitude of two contrasting species. 2 Proteomic responses to drought stress in two contrasting poplar species originating from different altitudes The cuttings from a female clone of P. kangdingensis and P. cathayana were used to determine proteomic response to drought stress, respectively. Total proteins of the leaves were extracted by a combination of TCA-acetone and phenol, and separated by two-dimensional gel electrophoresis. More than 1,000 protein spots were reproducibly detected on each gel. 58 differentially expressed spots were detected under drought stress in P. cathayana and 22 drought-responsive proteins were identified by peptide mass fingerprint. 69 differentially expressed spots were detected under drought stress in P. kangdingensiss and 25 drought-responsive proteins were identified by peptide mass fingerprint. The identified proteins are involved in several processes, i.e., signal transduction, protein processing, redox homeostasis, CO2 fixation and energy metabolism. Although the proteins identified in this investigation represent only a very small part of the poplar leaf proteins, some of the novel drought-responsive proteins identified here may be involved in the establishment of homeostasis in response to drought stress in the woody plants. 3 Responses to salt stress in P. cathayana Cuttings from a female clone of P. cathayana were treated by Hoagland’s solution: 0, 50, 100 mM NaCl, respectively. Salinity significantly decreased the relative water content of leaves, the contents of chlorophyll a and chlorophyll b, CO2 assimilation rate (A) and stomatal conductance (gs) in both salt stress treatments，which suggested the chloroplast was affected by salt stress. The observed increases of H2O2 and malondialdehyde contents and electrolyte leakage suggested that salinity caused cellular damage, whereas the increases in compatible solutes and in the activities of antioxidant enzymes enhanced the salt tolerance. More than 1,000 protein spots were reproducibly detected on each gel, and 38 salt-responsive proteins were successfully identified by peptide mass fingerprint (PMF). 16 spots (spot 4, 10, 11, 14, 15, 21, 24, 26, 27, 28, 33, 34, 35, 36, 37 and 38) absent in the control sample were induced by the salt treatment, and three spots (spot 10，11 and 35) were present only in the severely salt-stressed treatment. The %vol of the differentially expressed proteins generally increased with progressing salt stress, except for the decreased %vol of two proteins (spot 1 and 2) under salt stress and the presence of spot 1 only in the control sample. Some of the novel salt-responsive proteins identified here may be involved in physiological, biochemical response to salt stress in P. cathayana, the other identified proteins play a role in numerous cellular functions, including signal transduction and protein processing. An integrated physiological, biochemical and proteomic approach was used here to systematically investigate salt acclimation in poplar.

岷江干旱河谷三种蔷薇植物繁殖更新研究

繁殖更新是植物生活史的重要阶段，在退化生态系统中，植物繁殖更新能力往往较差，是植被恢复的限制环节，因而也成为恢复研究重点和核心。本研究选择岷江干旱河谷广泛分布的三种蔷薇：多苞蔷薇（R. multibracteata）、黄蔷薇（R. hugonis）和川滇蔷薇（R. soulieana）为研究对象，通过野外调查，在查明其生长、繁殖更新状况的基础上，采用控制和模拟实验，对种子和幼苗阶段进行了深入研究，综合分析更新潜力，并提出相对应的促进更新和植被恢复措施。主要结论如下： 1）三种蔷薇在岷江干旱河谷广泛分布，生长和繁殖状况良好，结实量大。各生长指标：株高、基径和冠幅，繁殖指标：结实数量、重量和单果重量都具有显著的空间差异性。基径对多苞蔷薇结实量影响最大；而冠幅对黄蔷薇结实量影响最大。海拔和纬度是对蔷薇生长和繁殖影响最大的环境因素，随着海拔和纬度的升高，植株生长更高大，结实量增加；坡度和坡向对其生长和繁殖也有一定影响，随着坡度 和坡向增加，蔷薇生长和结实受到抑制。 2）三种蔷薇在岷江干旱河谷更新现状不佳, 但更新潜力大。活力种子比率低，动物取食以及两年生幼苗的大量死亡是蔷薇更新的主要限制因素。多苞蔷薇和黄蔷薇的结实率低，川滇蔷薇较高。三种蔷薇种子产量大，但种子质量较差，更新具有充足的种源。三种蔷薇都能形成持久种子库，种子库中种子总量大，但有效种子少，黄蔷薇被动物啃食的比例很高，多苞蔷薇和川滇蔷薇也有一部分种子受到动物破坏。三种蔷薇幼苗库组成特征表现为，当年生幼苗所占比例很高，年龄较大幼苗所占比例小。 3）三种蔷薇都具有不同程度休眠，未经处理种子的发芽率极低。黄蔷薇休眠程度最深，为深度生理休眠；多苞蔷薇为中度生理休眠；川滇蔷薇为非深度生理休眠。三种蔷薇种子在形态上发育成熟，种皮具有透水性。蔷薇果果肉和瘦果中含有抑制物质，其浸泡液抑制了油菜种子萌发，果肉抑制作用更强，果肉和瘦果浸泡液的抑制程度分别为：川滇蔷薇>黄蔷薇>多苞蔷薇。切割和硫酸腐蚀提高了川滇蔷薇种子的发芽能力，而对多苞蔷薇和黄蔷薇没有影响。完全去除瘦果果皮和种皮提高了多苞蔷薇种子发芽率，但对黄蔷薇没有影响。赤霉素和烟水对蔷薇种子萌发没有促进作用。三种蔷薇打破休眠所需低温层积时间分别为：黄蔷薇>多苞蔷薇>川滇蔷薇。对于多苞蔷薇和川滇蔷薇，层积前对种子进行硫酸腐蚀或暖温层积能缩短低温层积时间，提高发芽率。对于多苞蔷薇，变温层积中暖温层积和低温层积具有一定的负补性，即延长暖温层积可以缩短种子萌发对低温层积的需要。 4）多苞蔷薇种子形态特征和种子休眠与萌发在不同海拔梯度间存在较大差异。种子采集时间、采集季节和干藏影响多苞蔷薇和川滇蔷薇的种子休眠。多苞蔷薇果实大小、种子大小和千粒重、种皮厚度随海拔升高而增加，而种子饱满率和活力随海拔升高而降低，种子休眠程度也随海拔升高而增加。种皮厚度与种子大小、千粒重成正相关关系，硫酸腐蚀后的种子经过不同时间的低温层积后，种子发芽率与种皮厚度、种子大小、千粒重、海拔成正相关关系。2006 年采集川滇蔷薇和多苞蔷薇种子休眠程度较2005 年低。种子休眠随种子年龄增加而减弱。高温和干旱能减轻多苞蔷薇和川滇蔷薇种子休眠。 5）三种蔷薇的生长和生物量积累在干旱胁迫条件下受到抑制，而生物量分配、叶片形态特征和水分利用特征等都发生了变化。三种蔷薇的根、茎、叶各器官生物量以及总生物量等在干旱胁迫下明显减小，叶片脱落数量增加。在干旱胁迫条件下，较多的生物量分配到地下部分，从而这使R/S 明显增加。比叶面积（SLA）和冠层面积比（LAR）对干旱胁迫的反应不敏感，仅有部分物种在干旱胁迫条件下发生了变化，并且其变化特点在不同年龄幼苗之间有一定差异。干旱胁迫对WUE 的影响在不同物种间存在差异。多苞蔷薇和黄蔷薇的WUE 随着干旱胁迫的增加而增大， 而川滇蔷薇的WUE 则随干旱胁迫增加而减小。在干旱胁迫条件下，多苞蔷薇和黄蔷薇叶片脱落量和生物量减小幅度较川滇蔷薇大，表明其抗旱能力较强。在干旱胁迫条件，三种蔷薇两年生幼苗的生物量减小幅度较当年生幼苗小，表明两年生幼苗的抗旱能力更强。 6）两种植被恢复措施中，幼苗移栽比播种具有更好的植被恢复效果。播种后，蔷薇种子的发芽率较高，但出苗率都很低，即使出苗，幼苗也几乎在一月内全部死亡。 三种微生境条件下（灌木、半灌木和裸地），种子出苗和幼苗成活没有差异。移栽幼苗总体死亡率都比较低，小于20％。特别是两年生幼苗死亡率更低，小于2％。移栽后的幼苗生长状况良好，在整个生长季中，各生长指标不断增加。生境对幼苗的存活率没有显著影响，但对于幼苗的生长和生物量积累有一定影响，裸地更有利于幼苗生长和生物量积累。与当年生幼苗相比，两年生幼苗具有更高的成活率。总之，三种蔷薇在干旱河谷分布广泛、生长繁殖状况良好，结实量大，具有丰富种源，繁殖更新潜力大，但繁殖更新状况不佳；种子散布后动物对种子的取食、种子的深度休眠过程、种子出苗以及当年生幼苗的存活和定居是更新的主要限制环节。水分是影响结实、种子休眠解除和萌发，幼苗存活和定居的最主要的限制因素。在植被恢复中，应在种子成熟季节大量采集种子，在室内打破休眠后进行人工播种，培育两年生幼苗，通过幼苗移栽方式进行植被恢复。川滇蔷薇应栽种在相对湿润的过渡区，而多苞蔷薇和黄蔷薇可以应用于核心区植被恢复。 Regeneration is an important phase in plant life cycle. It has been a key component of ecological restoration in degradation ecosystem in which plants commonly has poor regeneration. In this paper, we investigated the natural growth, propagation and regeneration status of native three rose species, Rosa multibracteata, R. hugonis and R. soulieana, and analysis the limitation in seed germination and seedling establishment stages. Advice on facilitating the use of these plants in restoration based on the results has been proposed. The results were as follows: 1) Three rose plants widely distributed in the dry valley of the Minjiang River, and made a good performance in growth and propagation. There were significant spatial differences in each growth parameter, such as ramet height, basal diameter, crown diameter and propagation parameters including hip number of a clump, hip mass of a clump and a hip mass. Basa diameter was the most important growth parameter influencing fruit number for R. multibracteata and crown diameter was for R. hugoni. Altitude and latitude had the greatest effect on the growth and propagation of rose plants among environmental conditions. Each parameter of growth and propagation increased with the increase of altitude and latitude. In addition, the increase of slope and aspect limited the growth and propagation. 2) Three rose plants had poor natural regeneration, but great regeneration potential. Low seed viability, predation and higher mortality of current year old seedlings were the limitation in regeneration. R. multibracteata and R. hugonis had higher fruiting rates than R. souliean. All three plants produced a great number of seeds, while their viability was poor. Three rose plants had persistent seed banks, with high total seed number but very low viable seed density. Predation was most severe in R. hugonis, and it also existed to some degree in R. multibracteata and R. soulieana. The seedling age-structure was characteristic of current-year seedlings predominating and few older seedlings were observed. 3) Three rose seeds were dormant and untreated seeds germinated with very low germination percentages. The rose seeds had morphological mature embryos, and achenes were permeable. Some inhabit substances existed in hips and achenes for the extracts of hips and achenes inhibited germination of Brassica campestris. The inhibition effect of the extracts of three rose hip and achenes was R. soulieana>R. hugonis>R. multibracteata. Mechanical and H2SO4 scarification increased R. soulieana germination but had no effect on germination of R. hugonis and R. multibracteata seeds. Full removal of pericarp and testa improved the germination of R. multibracteata but did not affect R. hugonis germination. GA3 and smoke water had no positive effect on rose seed germination. The periods of cold stratification required to released seed dormancy was R. hugonis > R. soulieana >R. multibracteata. H2SO4 scarification and warm stratification shortened cold stratification to release dormancy for R. soulieana and R. multibracteata. Warm stratification had complementary effect for cold stratification, i.e. the longer warm stratification seeds received, the shorter cold stratification were required to obtain the same germination percentage. Three rose seeds had different kinds of dormancy; R. hugonis has deep physiological dormancy, R. multibracteata with intermediate physiological dormancy and R. souliean non-deep physiological dormancy. 4）The seeds traits and dormancy of R. multibracteata showed significant difference across altitudes. Year and season of seed collection had significant effect on seed dormancy for both R. souliean and R. multibracteata. Hip size, seed size, seed weight, seed coat thickness and seed dormancy level increased with the increase of the altitude. There were positive relations between seed coat thickness with seed size and seed weight. Germination percentage of seeds treated with H2SO4 scarification following different periods of cold stratification showed positive relation with seed coat thickness, seed size, seed weight and altitude. Seeds of R. souliean and R. multibracteata collected in 2006 had low dormancy level than those collected in 2005. Seed dormancy decreased with increasing seeds age. High temperature and drought were associated with low dormancy level. 5) Seedling growth, the total dry mass and their components of seedlings were reduced, while leaf senescence accelerated under drought stress. More biomass allocation to root system resulted in higher R/S ratio under drought. Water-use efficiency (WUE) of R. multibracteata and R. hugonis increased, while it declined for R. soulieana under drought stress. R. soulieana seedlings had poor drought-resistance capacity it had more senescent leaves, and its reduction of biomass was stronger than two other rose plants under drought. The reduction degree of one year old seedlings under drought stress was slighter than that of current year seedlings. Therefore, one year old seedling was more drought-resistent compared to current year seedlings. 6）Planting seedlings may have better effect in comparison with direct seeding. Most seeds germinated after seeding, but seedling emergence was very low. More than 80 % seedlings from direct seeding died within a months after emergence. Seedling emergence and survival rate did not show difference among microhabitats. Mortality rates of seedlings artificially planted in microhabitats were general lower than 20 %, and the mortality rate of one year old seedlings was lower than 2 %. Each grow parameter including plant height, leaf number and branch number continually increased after planting. Microhabitat type had effect on the growth parameter and biomass production, but it did not influence the seedling survival. Bare land tended to facilitate seedling growth. One year old seedlings had higher survival rate than current year seedlings. In conculsion, the three rose had wide distribution in the dry valley of the Minjiang River. They produced many seeds and had tolerance to drought stress to some degree. But they had poor regeneration in habitats may be caused by predation, seed dormancy，and high mortality in current year seedlings. We recommend that rose plants should be utilized in restoration by planting two-year old seedlings in spring. A large quantity of seeds should be collected artificially in autumn, release seed dormancy in room, and then cultivate two-year old seedlings by seeding in particular container. R. soulieana seedling probably be planted in transition area, and R. multibracteata and R. hugonis can be used in core area of the dry valley of the Minjiang River.

增强UV-B辐射对粗枝云杉(Picea asperata Mast.)和青杨(Populus cathayana Rehd.)的影响

光是植物赖以生存的重要环境因子，但是植物在获得光的同时不可避免的会受到紫外辐射的伤害。尤其是近年来，人类向大气中排放的大量氮氧化合物和氟氯烃类化合物(CFC’s)引起臭氧分子的分解，导致到达地球表面的紫外辐射增加，特别是UV-B辐射增强。而另一方面，植物对UV-B辐射反应的敏感性在种间和品种间存在差异，主要受植物基因型，生态型和生活型的控制。本项目分别以粗枝云杉和青杨组杨树为模式植物，从形态和生理生化方面分别研究了来自不同水分背景下的粗枝云杉种群和来自不同UV-B背景下的青杨种群在增强UV-B下的反应及其反应差异,并探讨了干旱、喷施外源脱落酸(ABA)对它们抗UV-B能力的影响。研究成果可为生态系统的恢复与重建提供理论依据和科学指导。主要研究结果如下： 1. 粗枝云杉的两个种群，湿润种群(来自四川黑水)和干旱种群(来自甘肃迭部)在水分良好和干旱状况下表现出对增强UV-B的不同响应。同时，干旱对粗枝云杉抗UV-B能力的影响也得到研究：两种胁迫共同作用时，干旱表现出在一定程度上减弱了增强UV-B对粗枝云杉的生理特性的影响。 干旱胁迫显著降低了两个粗枝云杉种群的光合同化速率(A), 气孔导度(gs)和PSII的有效光量子产量(Y), 同时，提高了非光化学猝灭效率(qN)和超氧化物歧化酶(SOD)的活性。与湿润种群相比，干旱种群抗旱性更强，表现为干旱种群拥有更高的SOD和干旱进一步加剧了UV-B的胁迫效应。 本研究中，干旱胁迫单独作用时，显著降低了青杨两个种群的生物量积累和气体交换，具体包括A、gs、蒸腾速率(E)和光合氮利用效率(PNUE)，提高了两个种群的瞬时水分利用效率(WUEi)、长期水分利用效率(WUET)、碳同位素组分(δ13C)和氮含量(N)。同时，UV吸收物质和ABA含量也得到积累。另一方面，增强UV-B对青杨两个种群各个指标的影响，同干旱所引起的效应有着相似的趋势。同低海拔种群相比，高海拔种群有着更强的抗旱和抗UV-B能力，具体表现在高海拔种群有着更多的生物量积累，更强的气体交换和水分利用效率及更高水平的ABA和UV吸收物质含量。相比干旱诱导的生物量积累和气体交换的降低，在干旱和增强UV-B两个胁迫同时作用于青杨时，这种降低表现的更为明显。显著的干旱和UV-B的交互作用还表现在WUEi, WUET, δ13C, 可溶性蛋白含量, UV吸收物质含量, ABA, 叶片和茎中的N含量以及C/N比中。 3. 经过一个生长季的试验观察，增强UV-B、外源ABA及两因子共同作用对青杨的生物量积累、气体交换、内源ABA和UV吸收物质含量、抗氧化系统以及碳、氮含量和碳/氮比均产生显著影响。本试验中，青杨的两个种群分别来自中国西南部的不同海拔地区，高海拔种群来自青海大通而低海拔种群来自四川九寨。外源ABA的胁迫为直接喷施ABA到青杨叶片，而增强UV-B胁迫是利用平方波系统分别保证青杨苗暴露于外界UV-B强度和两倍于外界UV-B强度下。 研究结果显示，增强UV-B显著的降低了两个青杨种群的株高、基茎、总叶面积和总生物量等生长指标，同时也导致其A、gs、E和叶片中碳含量的减少。而显著增加了SOD和过氧化物酶(GPx)活性水平，诱导了过氧化氢(H2O2)和MDA的显著增加，促进了UV吸收物质和不同器官中内源ABA含量的显著积累。另一方面，外源ABA引起了青杨光合同化速率的下降，SOD和GPx酶活性的增强，H2O2 和 MDA含量也表现出显著增加，同时，内源ABA含量得到显著累积。同低海拔种群相比，高海拔种群具有更加抗UV-B和外源ABA的特性。显著的UV-B和ABA的交互作用表现在A, E, SOD和GPx活性，以及叶片和根部的内源ABA等一系列指标中。在所有胁迫下，叶片中的碳和氮含量同其在茎和根中的含量显著相关，另外，叶片和茎中的氮含量同茎中的碳含量显著相关。 Sunlight is an indispensable environment factor for plants survival and development. Meanwhile, photosynthetic organisms need sunlight and are thus, inevitably, exposed to UV radiation. Especially for recent years, ultraviolet radiation, especially UV-B reaching the Earth’s surface increased because of depletion of ozone layer resulted from emission of NxO and CFC’s from human activities. On the other hand, the sensitivity of plants to UV-B radiation depends on the species, developmental stage and experimental conditions. In this experiment, two populations of Picea asperata Mast from different water background and two populations of Populus cathayana Rehder from different altitude background were selected as model plants to assess the effects of enhanced UV-B radiation. Morphological and physiological traits induced by enhanced UV-B in each plant species were observed and the different responses were discussed, furthermore the influences of drought and exogenous ABA on responses induced by enhanced UV-B were studied. The study could provide a strong theoretical evidence and scientific direction for the afforestation and rehabilitation of ecosystem. The results are as follows: 1. Different responses of two contrasting Picea asperata Mast. populations to enhanced ultraviolet-B (UV-B) radiation under well-watered and drought conditions were investigated. And the effects of enhanced UV-B on tolerance of drought were also observed in our study that the UV-B exposure may have alleviated some of the damage induced by drought. Two contrasting populations, originating from a wet and dry climate region in China, respectively, were employed in our study. Drought significantly decreased CO2 assimilation rate (A), stomatal conductance (gs) and effective PSII quantum yield (Y), while it significantly increased non-photochemical quenching (qN) and the activity of superoxide dismutase (SOD) in both populations. Compared with the wet climate population, the dry climate population was more acclimated to drought stress and showed much higher activities of SOD and ascorbate peroxidase (APX), and much lower levels of malondialdehyde (MDA) and electrolyte leakage. On the other hand, enhanced UV-B radiation also induced a significant decrease in the chlorophyll (Chl) content in both populations under well-watered conditions, and a significant increase in UV-absorbing compounds in the wet climate population. After one growing season of exposure to different UV-B levels and watering regimes, the increases in MDA and electrolyte leakage, as induced by drought, were less pronounced under the combination of UV-B and drought. In addition, an additive effect of drought and UV-B on A and gs was observed in the wet climate population, and on the activity of APX and qN in the dry climate population. 2. The significant effects of drought, enhanced UV-B radiation and their combination on Populus cathayana Rehd. growth and physiological traits were investigated in two populations, originating from high and low altitudes in south-west China. Our results showed that UV-B acts as an important signal allowing P. cathayana seedlings to respond to drought and that the combination of drought and UV-B may cause synergistically detrimental effects on plant growth in both populations. In both populations, drought significantly decreased biomass accumulation and gas exchange parameters, including A, gs, E and photosynthetic nitrogen use efficiency (PNUE). However, instantaneous water use efficiency (WUEi), transpiration efficiency (WUET), carbon isotope composition (δ13C) and nitrogen (N) content, as well as the accumulation of soluble protein, UV-absorbing compounds and abscisic acid (ABA) were significantly increased by drought. On the other hand, cuttings from both populations, when kept under enhanced UV-B radiation conditions, showed very similar changes in all above-mentioned parameters, as induced by drought. Compared with the low altitude population, the high altitude population was more tolerant to drought and enhanced UV-B, as indicated by the higher level of biomass accumulation, gas exchange, water-use efficiency, ABA concentration and UV-absorbing compounds. After one growing season of exposure to different UV-B levels and watering regimes, the decrease in biomass accumulation and gas exchange, induced by drought, was more pronounced under the combination of UV-B and drought. Significant interactions between drought and UV-B were observed in WUEi, WUET, δ13C, soluble protein, UV-absorbing compounds, ABA and in the leaf and stem N, as well as in the leaf and stem C/N ratio. 3. During one growing season, significant effects induced by enhanced UV-B radiation, exogenous ABA and their combination on biomass accumulation, gas exchange, endogenous ABA and UV-absorbing compounds concentrations, antioxidant system as well as carbon (C) content, nitrogen (N) content and C/N ratio were investigated in two contrasting Populus cathayana populations, originating from high and low altitudes in south-west China. Exogenous ABA was sprayed to the leaves and enhanced UV-B treatment was using a square-wave system to make the seedlings under ambient (1×) or twice ambient (2×) doses of biologically effective UV-B radiation (UV-BBE). Enhanced UV-B radiation significantly decreased height, basal diameter, total leaf area, total biomass, A, gs, E and carbon (C) content in leaves, and significantly increased activities of SOD and guaiacol peroxidase (GPx), hydrogen peroxide (H2O2) and malonaldehyde (MDA) content as well as the accumulation of UV-absorbing compounds and endogenous ABA concentrations among different organs in both populations. In contrast, exogenous ABA showed significant decrease in A and significant increases in activities of SOD and GPx, H2O2, MDA content and the endogenous ABA concentrations. Compared with the low altitude population, the high altitude population was more tolerant to enhanced UV-B and exogenous ABA. Significant interactions between UV-B and ABA were observed in A, E, activities of SOD and GPx, as well as in endogenous ABA in leaves and roots of both populations. Across all treatments, C and N content in leaves was strongly correlated with those were in stems and roots, respectively. Additionally, leaf and stem N content were significant correlated with stem C content.

青杨(Populus cathayana Rehd.)对逆境胁迫的反应及lea基因的表达分析

杨树具有分布广、适应性强，在生态环境治理和解决木材短缺方面均占有重要位置。青杨(Populus cathayana Rehd.)是青杨派树种的重要成员之一，也是我国的特有种。本研究通过对不同水分梯度的干旱胁迫下青杨形态和生理生化的反应，不同pH值盐碱胁迫下不同海拔和不同气候地区的四个青杨种群在生理生态上的反应差异，以及在干旱和低温胁迫下青杨lea2, lea3组基因表达差异的研究，从形态、生理、生化和分子生物学水平系统地研究了青杨在不同逆境胁迫下的反应和青杨不同种群在盐碱胁迫下的反应差异。主要研究结果如下： 1. 青杨在干旱胁迫下的反应机制：中度和重度干旱胁迫下植株的生长受到明显抑制。表现在光合系统上青杨的净光合同化速率(A)下降，主要原因是气孔导度(gs)，胞间二氧化碳浓度(Ci)下降。另外最大量子产量(Fv/Fm)、光化学猝灭效率(qP)降低反应了干旱胁迫下光合系统II(PSII)受到严重损伤, 而且非光化学猝灭效率(qN)上升，导致可利用化学能产量下降，叶绿体产生淀粉的量减少。qP降低qN上升导致产生的过量电子对光合系统的伤害造成活性氧以及丙二醛(MDA)的含量增加。超微解剖结构显示，干旱胁迫增强时，叶绿体内淀粉粒的数目减少，而且叶绿体、线粒体等细胞器中嗜锇颗粒的数目增加。为清除细胞内的活性氧，植物一般的反应是抗氧化系统酶活性增加，对青杨来讲超氧化物歧化酶(SOD), 抗坏血酸过氧化物酶(APx)活性的增加远大于过氧化物酶(POD)，这显示了在青杨中SOD、APx酶在清除活性氧的作用上大于POD。另外同工酶研究结果显示这些酶活性的升高主要是由于各条同工酶带表达量的增加，而不是诱导新酶带的产生。另外，75% FC水分处理下有些指标非但没有下降，像A和有效光量子产量(Y)的值都略有增加，而且gs同时增加。另外，100% FC比75% FC细胞内淀粉粒的数目少一些，但有少量的嗜锇颗粒。这证明100% FC土壤水分也许并非最适合青杨生长。 2. 盐碱胁迫对不同海拔地区青杨种群的反应差异：青杨高海拔和低海拔种群的各种生理特性随着pH值上升都受到了很大的影响。两种群叶和根中Na+、K+ 含量, Na+/K+比率随着pH值的上升影响显著。在pH值高于10.4时高海拔种群叶和根中Na+/K+比率急剧下降但是低海拔种群中却一直维持在较高水平。两种群中MDA、脯氨酸(Proline)的含量，抗氧化系统酶的活性都受到了严重的影响，证明两个种群都属于盐碱胁迫敏感类型但是高海拔的种群对盐碱胁迫的耐性要高于低海拔。这主要是由于高海拔种群一般具有耐干旱、低温胁迫的能力，而植物的抗逆机制一般都有共通之处。 3. 盐碱胁迫对不同气候地区青杨种群的反应差异：盐碱胁迫下两种群的光合作用受到明显的抑制，具体表现在叶绿素的含量和A 显著下降。净光合速率的下降主要是由于叶片gs，Ci 值降低引起的。与湿润地区的种群相比盐碱胁迫增强时，干旱地区的种群叶绿素含量和光合能力的升高与K+离子含量增加有关。植物维持细胞质高K+/Na+值对植物的抗盐性有很重要的作用。为清除盐碱胁迫产生的活性氧，抗氧化系统酶活性增加。盐碱胁迫下干旱地区的种群在SOD、CAT 和谷胱甘肽还原酶(GR)等酶的活性均显著上升，而湿润地区种群只有谷胱甘肽氧化酶(GST)的活性明显增加，说明干旱种群的抗氧化酶系统在较高盐碱胁迫下的保护作用要强于湿润种群。这主要是由于植物抗盐碱胁迫与抗干旱胁迫在一些方面的机制是一致的，抗旱种群一般也能抵抗一定程度的盐碱胁迫。 4. 青杨lea2、lea3 基因在干旱和低温胁迫下的表达差异：通过荧光定量PCR 分析，lea2、lea3 组基因在干旱和低温胁迫下在mRNA 水平的瞬时表达量明显升高，说明了两基因在青杨耐干旱和低温胁迫上都起显著的作用。而且两基因在干旱胁迫下，表达量的升高和降低的时间近乎同步，表明两基因在干旱胁迫下对植物应急保护机制的启动都发挥着重要的作用。低温胁迫下lea3 基因在mRNA 水平上表达量显著上升的时间要早于lea2，而且lea3 基因的持续作用时间明显长于lea2 组基因，说明了低温胁迫开始时lea3基因在植物应对逆境的作用上要大于lea2 基因。 Poplars play an important role in lumber supply, and are important components of ecosystems due to their wide distribution and well adaptation. Populus cathayana Rehd., which belongs to Populus Sect. Tacamahaca Spach, is one of the most important resources of poplars and is specialist to china. In this study, different altitudes and climates populations of P. cathayana were used as experiment materials to investigate the adaptability to drought and salt-alkali stresses. And the cultures of P. cathayana were used to analyze the lea2 and 3 group genes expression when exposed to drought and low temperature stresses. The results are as follows: 1. A large set of parallel responses to drought stress: Drought stress caused pronounced growth inhibition. A decreased significantly and was mainly the result of gs and Ci down. Besides, Fv/Fm, qP decreased and that reflected the harmful effects to PSII of drought stress. In accordance with qN increasing, decreased useful energy production caused the starch numbers reduction in chloroplast. The qP up and qN down improved the levels of ROS and MDA. Starch numbers in chloroplast reduced and plastoglobuli numbers increased when soil water content decreased. To reduce ROS, the activities of SOD, APX, CAT and PPO were activated. The isozymes results show that the rising activities of the antioxidant enzymes resulted from certain isoform content increased, and not from the new band produced. Interestingly, morphological results show 100%FC maybe wasn’t the favorite water content for P. cathayana growth. 2. Effect of salt-alkali stress on morphological and physiological changes in two different altitudes populations of P. cathayana: We compared the physiological responses of two populations of Populus cathayana Rehder, originating from altitudes 2,840 m and 1,450 m. Our results demonstated that Na+ and K+ contents, and Na+/K+ ratios in leaves and roots are greatly affected by pH values. At pH 10.4, the Na+/K+ ratios in both leaves and roots sharply dropped in the higher altitude population but were always maintained at higher levels in the lower altitude population. The pH values causing maximum malondialdehyde (MDA) level, free proline content and antioxidant enzyme activities were significantly different in two populations. These results indicated that the higher altitude population exhibits greater tolerance to alkalinity stress than does the lower altitude population. 3. Morphological and physiological changes in two different climates populations of P. cathayana when exposed to salt-alkali stress. Salt-alkali stress caused pronounced inhibition of the growth and especially in photosystem. Pigments content and A decreased significantly and at the same time gs and Ci decreased too. Compared with wet climate population, the Chlorophyll content and A increased in drought climate population as pH value rising was related to the K+ content increasing. It is important to resist salt-alkali stress that the K+/Na+ ratio matained at high level in cytoplasm. To reduce ROS content, the SOD, CAT and GR activities rised significantly in drought population but only GST increased in wet population. The drought population showed higher salt-alkali tolerance than the wet population mainly resulted from the fact that drought tolerance was in accordance with salt-alkali tolerance to some extent. 4. The different expressional model of lea2 and lea3 gene when P. cathayana was exposed to drought and cold stress. RT-PCR results show both lea2 and lea3 suddenly expressed significantly in mRNA level under drought and cold stress. The expression level of two genes reached optimal level at the same time. But under cold stress, the earlier significantly rising expressional time and the longer maintained higher level time in lea3 than lea2 elucidated that lea3 may be more important than lea2 in resisting cold stress in short time in P. cathayana.

青杨(Populus cathayana Rehd)雌雄植株对锈病和干旱胁迫的生理响应及差异蛋白质组比较

雌雄异株植物对环境的不同响应一直是一个有趣而新颖的研究领域，由于雌雄个体不同的繁殖成本及不同的生存策略，使得雌雄植株在生长、存活、生殖格局、空间分布、资源配置等方面已经表现出明显的不同，在生理和分子水平上也表现出明显的性别间差异。干旱是制约农林业发展的环境因子之一，叶锈病是对杨树危害最严重的病害之一，由于长期进化的结果，不同性别的植物必然对生物和非生物胁迫有着不同的响应。本文以雌雄异株的青杨为模式植物，研究雌雄间在生理、生化、亚细胞结构和蛋白质水平上对生物和非生物胁迫的差异响应。主要研究结果如下： （1） 青杨雌雄植株对锈病胁迫的生理生化差异响应 在正常的对照组中，雄株叶片比雌株叶片有着较高的活性氧自由基产生速率、较高的SOD、POD、PPO 和较低的CAT 活性；在锈病感染的早期阶段， SOD、POD、CAT 活性、活性氧自由基产生速率、H2O2 含量、膜脂过氧化程度和细胞膜的电渗率在雌雄株中都增加，而PPO 仅在雄株中增加明显，APX 仅在雌株中增加明显，并且雌株比雄株有着更严重的锈病感染程度、细胞膜的伤害程度和光合系统II 的破坏程度，雌株有更多的净光合速率、气孔导度和叶绿素a 含量的降低，在同工酶变化上，雌雄间对锈病也显示出不同的表达模式。结果显示，雄株比雌株对锈病有着更好的抗性和更有效的ROS 清除系统。 （2） 青杨雌雄植株对干旱胁迫的生理生化及亚细胞结构的差异响应 与较好水分条件相比，干旱下雄株比雌株有着更高的A-Ci 响应参数，如Rubisco 最大羧化速率、光呼吸速率、暗呼吸速率和最大电子传递速率等。干旱显著地增加了膜脂过氧化程度和游离脯氨酸含量，并且雄株比雌株表现出较低的膜脂过氧化程度，较高的总蛋白和游离脯氨酸含量。无论是中度干旱还是极度干旱，除了CAT 外，雄株比雌株表现为较强的抗氧化酶活性，在同工酶谱带上，雌雄间表现出不同的变化模式，并且有些条带是干旱影响应的，而有些条带是性别特异性的，这些性别特异性条带能够作为鉴定性别快速而准确的标记。干旱显著地影响了线粒体、叶绿体和细胞壁的结构，尤其在中度干旱胁迫下，雄株线粒体和叶绿体比雌株呈现出较好的完整性，并且雄株细胞壁要比雌株更厚。因此， 雄株比雌株表现出更强的干旱忍耐性和更高效的抗氧化酶系统。 （3） 青杨雌雄植株对干旱胁迫的蛋白质组差异响应 用双相电泳检测到雌雄间近1000 个蛋白点，通过对比发现对照组雌雄间有54 个差异蛋白点，干旱下雌雄间有108 个差异点，其中102 个被质谱成功鉴定。对照组雌雄间的差异蛋白主要集中在与光合作用相关蛋白、抗氧化酶、胁迫防御蛋白和一些调节基因表达的蛋白；干旱胁迫下雌雄间差异蛋白明显增多，主要有参与信号转导、调节基因表达、蛋白质加工、转录产物的转录翻译后修饰的调节性蛋白蛋白和参与氧化还原平衡、抗胁迫、细胞壁合成、光合作用、能量代谢、氨基酸代谢和脂肪酸代谢等的功能性蛋白。干旱下这些蛋白的表达量在雌雄中有的表现出相同的表达模式，如干旱下雌雄株中Rubisco 激活酶、小热激蛋白等表达都增加，而有的表现出相反的表达模式，如Rubisco 大亚基的降解片段、羰酸酯酶等在雄株中表达量上调而在雌株中却是下调。因此，雌雄间在蛋白质水平上对干旱胁迫响应的差异是显著的，也是复杂的。 It is an interesting and novel topic that dioecious plants possess different responses to environmental stress. As for the different productive cost and different survive strategy, different sexual plants have shown obviously morphological, physiological and molecular differences. Drought is one of the most worldwidely important environmental stress factors that limit plant growth and ecosystem productivity. Rust disease is one of the economically important diseases in many trees. As a result of the long evolutionary process, male and female plants should show different responses to abiotic and biotic stress. In this paper, using a dioeious tree of Populus cathayana Rehd as a model, we study the sexual differences to drought and rust disease stress in physiological, biochemical, sub-cellular and proteomics levels. The main results are follows: (1) The sexual differences in physiology and biochemistry of poplar to rust disease In controls, males showed higher production of superoxide radicals, higher activities of SOD, POD, PPO and lower CAT activity. Under rust disease, the activities of antioxidant, the content of ROS and the degree of cellular member destroyed were increased in both sexes, except for PPO in diseased males and APX in diseased females. However, females showed more seriously disease severity and cellular member and PS II destroyed degrees. Net photosynthesis rate, transpiration rate and chlorophyll a content were decreased more in diseased females than in males. There were also some different changes inantioxidant isozymes under rust disease. The results suggested that male poplar possessed a more effectively antioxidant system and were more resistant to rut disease than females. (2) The sexual differences in physiology and biochemistry of poplar to drought stress Under drought stress, there were higher rates of RuBP-saturated CO2 assimilation, dark respiration, photorespiratory release of oxygen, the max electron transportrate in CO2-saturated and carboxylation efficiency in males than in females. And males showed lower TBARS and higher proline content. Except for CAT, the activities of other antioxidants were higher in males than in females. Meanwhile, there were obviously differences in isozyme changes between teo sexes. Drought stress obviously destroyed the integralities of chloroplasts and mitochondria and the sexual differences in sub-cellular level were obviously under the moderate water stress. Male cell walls were more sensitive to drought stress than did female. The results suggested males were more resistant to drought stress. (3) The sexual differences in proteomics of poplar to drought stress By 2-D and MS analysis, we identified 102 different protein spots between males and females. Under control conditions, the different proteins were mainly in photosynthesis related proteins, antioxidants, stress response proteins and some gene expression related proteins. Under drought stress, the different proteins were focused on (i) regulated proteins such as signaling conduction, kinase, HSP, gene expressional regulation and protein modification, (ii) functional proteins such as photosynthesis, energy metabolism, antioxidant, redox, stress response, lipid metabolism and amino acid metabolism. Some protein showed the same expressional pattern, while some showed contrary expressional pattern. Thus, the results suggested that sexual differences in proteomics were significant and complex.