Physiological responses to capture and handling of free-ranging male Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis)

We captured free-ranging male Yangtze finless porpoises over three seasons and assayed leukocytes and serum biochemistry to investigate physiological responses to the capture and handlings. Serum thyroid hormones (THs) declined sharply in those porpoises compared with hormone variation in a captive male finless porpoise. Hypernatremia and hypokalemia were also significant in the free-ranging animals suggesting that conservation of serum sodium might be acutely vital for this freshwater subspecies. The animals captured in spring showed more significant neutrophilia and eosinopenia than those captured in autumn suggesting that they may be more affected by capture during the breeding season. Furthermore, physical examination of porpoises when out of the water was apparently stressful, particularly when they were kept out of the water for longer periods. However, an increase in circulating THs may be an adaptive response to accommodate these short-term stresses.

Physiological Responses of Microcystis aeruginosa PCC7806 to Nonanoic Acid Stress

A recent study has shown that nonanoic acid (NA) is one of the strongest allelochemicals to a cyanobacterium Microcystis aeruginosa, but the physiological responses of M. aeruginosa to NA stress remain unknown. In this study, physiological characters such as the growth rate, photosynthetic processes, phosphorus and nitrogen uptake kinetics, and the contents of intracellular microcystin of M. aeruginosa PCC7806 were studied under the NA stress. The results showed that the growth rates of M. aeruginosa PCC 7806 were significantly inhibited in all NA stress treatments during first 3 days after exposure, and the growth rate was recovered after 5-day exposure. After 2-day exposure, the contents of both phycocyanin and allophycocyanin per cell decreased at NA concentration of 4 mg L-1, and oxygen evolution was inhibited even at the concentration of 0.5 mg L-1, but carotenoid content per cell was slightly boosted in NA stress. Physiological recovery of M. aeruginosa PCC7806 was observed after 7-day exposure to NA. It was shown that NA stress had no effect on uptake of nitrogen, but could stimulate the uptake of phosphorus. The contents of intracellular microcystin have not been affected in all NA treatments in contrast with the control. (C) 2008 Wiley Periodicals, Inc. Environ Toxicol 24: 610-617, 2009.

Comparative studies on physiological responses to phosphorus in two phenotypes of bloom-forming Microcystis

Toxic Microcystis blooms frequently occur in eutrophic water bodies and exist in the form of colonial and unicellular cells. In order to understand the mechanism of Microcystis dominance in freshwater bodies, the physiological and biochemical responses of unicellular ( 4 strains) and colonial ( 4 strains) Microcystis strains to phosphorus ( P) were comparatively studied. The two phenotype strains exhibit physiological differences mainly in terms of their response to low P concentrations. The growth of four unicellular and one small colonial Microcystis strain was significantly inhibited at a P concentration of 0.2 mg l - 1; however, that of the large colonial Microcystis strains was not inhibited. The results of phosphate uptake experiments conducted using P- starved cells indicated that the colonial strains had a higher affinity for low levels of P. The unicellular strains consumed more P than the colonial strains. Alkaline phosphatase activity in the unicellular strains was significantly induced by low P concentrations. Under P- limited conditions, the oxygen evolution rate, Fv/ Fm, and ETRmax were lower in unicellular strains than in colonial strains. These findings may shed light on the mechanism by which colonial Microcystis strains have an advantage with regard to dominance and persistence in fluctuating P conditions.

Effects of CO2 enrichment on the bloom-forming cyanobacterium Microcystis aeruginosa (Cyanophyceae): Physiological responses and relationships with the availability of dissolved inorganic carbon

Microcystis aeruginosa Kutz. 7820 was cultured at 350 and 700 muL.L-1 CO2 to assess the impacts of doubled atmospheric CO2 concentration on this bloom-forming cyanobacterium. Doubling Of CO2 concentration in the airflow enhanced its growth by 52%-77%, with pH values decreased and dissolved inorganic carbon (DIC) increased in the medium. Photosynthetic efficiencies and dark respiratory rates expressed per unit chl a tended to increase with the doubling of CO2. However, saturating irradiances for photosynthesis and light-saturated photosynthetic rates normalized to cell number tended to decrease with the increase of DIC in the medium. Doubling of CO2 concentration in the airflow had less effect on DIC-saturated photosynthetic rates and apparent photosynthetic affinities for DIC. In the exponential phase, CO2 and HCO3- levels in the medium were higher than those required to saturate photosynthesis. Cultures with surface aeration were DIC limited in the stationary phase. The rate of CO2 dissolution into the liquid increased proportionally when CO2 in air was raised from 350 to 700 muL.L-1, thus increasing the availability of DIC in the medium and enhancing the rate of photosynthesis. Doubled CO2 could enhance CO2 dissolution, lower pH values, and influence the ionization fractions of various DIC species even when the photosynthesis was not DIC limited. Consequently, HCO3- concentrations in cultures were significantly higher than in controls, and the photosynthetic energy cost for the operation of CO2 concentrating mechanism might decrease.

冬枣果实对不同贮藏条件的生理反应及耐贮性研究

本文以我国特有的冬枣果实为试材，系统地研究了冬枣果实在室温、低温和不同O2和CO2浓度气调贮藏条件下的生理特性、风味品质和贮藏性，提出了适合于冬枣果实生理特性的气调指标和贮藏时间;分析了冬枣在不同贮藏条件下果实硬度、颜色、叶绿素和花青素、可溶性固形物、可滴定酸、Vc、乙醇和乙酸乙酯等物质成分的含量变化及与果实风味品质的关系;同时也分析了多酚氧化酶（PPO）、苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、多聚半乳糖醛酸酶（PG）和脂氧合酶（LOX）的活性变化情况以及丙二醛（MDA）含量和膜透性的变化情况，揭示了它们与冬枣果实转红、酒化、褐变、软化、衰老、及耐贮性的关系。对冬枣果实在气调贮藏中的生理反应和品质变化的研究，为形成冬枣果实采后商业化贮藏的系列配套技术提供了理论依据。试验结果表明： 1、冬枣果实在不同贮藏环境下品质的变化：随着贮藏时间的延长，冬枣果实Vc含量呈明显下降的趋势，CA处理能有效地抑制果实Vc含量的下降;不同贮藏条件对冬枣果实SSC影响不大;冬枣果实花青素的含量随贮藏时间逐渐下降，高O2浓度（70%）动态气调与其它处理相比，能更有效保持冬枣果实果皮的颜色及花青素和叶绿素的含量，以及果实的亮度、颜色饱和度和色度;同时，还能降低贮藏前期冬枣果实乙醇释放量。 2、冬枣果实在不同贮藏环境下生理的变化：（1） PG 酶是影响冬枣果实软化的主要因素，冬枣果实中存在内切和外切两种PG 酶，在冬枣果实的成熟过程中，Exo-PG和Endo-PG迅速积累，并呈现较高的活性，多聚半乳糖醛酸酶活性与冬枣果实的软化密切相关。CA贮藏与普通冷藏相比，可有效地抑制冬枣果实多聚半乳糖醛酸酶的活性和延缓果实软化，其中以5% O2的CA贮藏的效果最好。（2）膜质过氧化是造成冬枣果实褐变的主要因素，在室温下冬枣果实细胞膜透性随贮藏时间逐渐上升，CA贮藏在贮藏前中期可有效控制MDA含量的上升和果实褐变的发生，有利于降低膜脂过氧化程度，保护细胞膜结构并延缓果实衰老。冬枣果实褐变与PPO活性关系不大，但与膜透性及膜质过氧化作用的产物—丙二醛（MAD）含量变化显著相关。（3）冬枣果实采收时的SOD活性很低，在25 C下，果实SOD活性急剧上升，低温贮藏条件下，果实SOD活性出现两次高峰，第一次高峰为果实后熟的标志，第二次高峰标志着果实的衰老。（4）在不同贮藏条件下，冬枣果实PAL活性均随贮藏期的延长而呈现下降趋势。 3、影响冬枣果实贮藏性的生理因素：冬枣果实的衰老与活性氧代谢失调和防御体系活力下降有关，随着果实衰老的出现，果实的POD、CAT等保护酶活性均呈现明显下降的趋势。气调贮藏在前期能显著提高冬枣果实POD的活性，而在后期又显著抑制了POD活性的上升，说明POD在果实贮藏初期表现为保护效应，而在后期则表现为伤害效应。 4、冬枣果实适宜的贮藏条件：与普通冷藏相比，气调贮藏（CA）能明显地延缓果实衰老，减少腐烂和褐变，保持风味品质和延长贮藏时间。其中以较高O2浓度的（10% O2 + 0% CO2）气调贮藏效果最好。气调贮藏与杀菌剂配合有利于延长冬枣的贮藏期，0.1%的施保克和0.1%戴挫霉处理能有效控制冬枣果实贮藏期间的腐烂，延长贮藏时间，施保克的防腐效果好于戴挫霉。 5、拮抗菌和病原菌处理对冬枣果实抗性相关酶的诱导：接种拮抗菌+病原菌或只接种病原菌能诱导冬枣果实蛋白含量的显著升高，说明拮抗菌和病原菌处理诱导了果实病原相关蛋白的积累。在常温条件下，拮抗菌和病原菌处理抑制了冬枣果实的CAT酶活性，诱导了SOD和POD活性的上升。同时果实的蛋白含量也显著升高。在低温条件下，CAT和SOD活性受抑制，POD、PPO和 PAL活性被诱导并显著高于正常果实。这说明拮抗菌处理的冬枣果实可能通过加强氧化酶活性的方式来达到抗病的效果。拮抗菌和病原菌处理后，该部分组织的氧化酶活性加强，它们可以分解毒素，促进伤口愈合，抑制病原菌水解酶活性，从而抵抗病害的扩展。PAL是催化莽草酸途径的关键酶，可合成酚、植保素和木质素，而这些物质均与植物抗性有关。

Impacts of CO2 enrichment on growth and photosynthesis in freshwater and marine diatoms

The physiological responses of Nitzschia palea Kutzing, a freshwater diatom, to elevated CO2 were investigated and compared with those of a marine diatom, Chaetoceros muelleri Lemmermann previously reported. Elevated CO2 concentration to 700 mu l/L increased the dissolved inorganic carbon (DIC) and lowered the pH in the cultures of N. palea, thus enhancing the growth by 4%-20% during the whole growth period. High CO2-grown N. palea cells showed lower levels of dark respiration rates and higher I (k) values. Light-saturated photosynthetic rates and photosynthetic efficiencies decreased in N. palea with the doubling CO2 concentration in airflow to the bottom of cultures, although the doubling CO2 concentration in airflow to the surface cultures had few effects on these two photosynthetic parameters. N. palea cells were found to be capable of using HCO3 (-) in addition to gaseous CO2, and the CO2 enrichment decreased their affinity for HCO3 (-) and CO2. Although doubled CO2 level would enhance the biomass of N. palea and C. muelleri to different extents, compared with the marine diatom, it had a significant effect on the specific growth rates of N. palea. In addition, the responses of photosynthetic parameters of N. palea to doubled CO2 concentration were almost opposite to those of C. muelleri.

中国卧龙自然保护区不同海拔川滇高山栎(Quercus aquifolioides)群体的遗传变异

海拔梯度造成的环境异质性，如崎岖的地形、复杂的植被结构以及花期延迟等可能会极大地影响到物种的形态和遗传变异格局。理解物种形态和遗传变异的海拔格局对于物种多样性的管理和保护是非常重要的。尽管植物群体遗传学是一个飞速发展的研究领域，然而与海拔相关的形态变异、遗传变异及群体间遗传差异的研究却很少。到目前为止，还不清楚遗传变异与海拔之间是否必然的相关性。 川滇高山栎是一种重要的生态和经济型树种，广泛分布于中国西南的四川、西藏、贵州和云南省的高海拔地区，在保持水土、调节气候方面起着十分重要的作用。尽管主要受阳光限制而仅分布于阳坡，但其海拔梯度范围较大，表明川滇高山栎对不同的环境具有很强的适应性。本文通过叶型及生理响应、微卫星分子标记和扩增性片段长度多态性方法，试图探索川滇高山栎叶沿海拔梯度的形态和生理响应及其沿海拔梯度的遗传变异格局，为川滇高山栎的保护和利用提供进一步的遗传学理论依据和技术指导。 对叶形、含氮量及碳同位素的试验结果表明，平均比叶面积、气孔密度、气孔长度和气孔指数等气孔参数随海拔的升高呈非线性变化。在海拔大于2800 m时，川滇高山栎的比叶面积、气孔长度和气孔指数都随海拔升高而降低，但是在海拔小于2800 m时，这些指标都随海拔的升高而增大。相对而言，单位叶面积的含氮量和碳同位素则表现出相反的变化模式。另外，比叶面积是决定碳同位素沿海拔梯度变化的最重要参数。本研究结果表明，海拔2800 m附近是川滇高山栎生长和发育的最适地带，在这里生长的植物叶片厚度更薄、气孔更大、叶碳同位素值更小。 利用六对微卫星引物对五个不同海拔川滇高山栎群体遗传多样性进行研究，结果表明，群体内表现出较高的遗传多样性，平均每位点等位基因数11.33个，平均期望杂合度达0.820。群体间差异较小，分化仅为6.6％。聚类分析也并没有显示出明显的海拔格局。然而低频率等位基因却与海拔呈显著性正相关(R2=0.97, P < 0.01)，表明在高海拔处，川滇高山栎以更多的稀有基因来适应恶劣的环境条件。本试验结果表明由海拔梯度形成的选择性压力对川滇高山栎群体的遗传变异影响并不明显。 为了进一步探讨川滇高山栎群体遗传变异与海拔之间的相互关系，我们还对其进行了扩增性片段长度多态性分析。结果表明：(1)随海拔的升高(从群体WL2到群体WL5)，群体内遗传变异降低，而群体间遗传差异增加；(2)低海拔群体WL1表现出最低的遗传变异性(HE = 0.181)，同时与其余四个群体间呈现出最大的遗传差异性(平均FST = 0.0596)；(3)在除去低海拔群体WL1后，Mantel检测表明群体间遗传距离与海拔距离之间表现出正相关性。另外，研究结果还表明，遗传变异受生境条件(过度的湿热环境)及人为干扰(火烧、砍伐和放牧)的影响，这一点至少在低海拔群体WL1上发生了作用。 通过叶形态、生理及DNA分子水平的研究，结果表明叶形态特征和碳同位素与海拔紧密相关，与海拔之间呈非线性变化，海拔2,800 m附近是川滇高山栎生长和发育的最适地带。海拔梯度在一定程度上会影响到川滇高山栎群体的遗传变异结构，但在这样一个狭窄的地理分布区域里，这种影响并不足以导致群体间较大的遗传分化。同时生境条件及人为干扰也是影响遗传变异的限制性因子，不容忽视。 Altitudinal gradients impose heterogeneous environmental conditions, such as rugged topography, a complex pattern of vegetation and flowering delay, and they likely furthermore markedly affect the morphological and genetic variation pattern of a species. Understanding altitudinal pattern of morphological and genetic variation at a species is important for the management and conservation of species diversity. Although plant population genetics is a fast growing field of research, there are only few recent investigations, which analyzed the genetic differentiation and changes of intra-population variation along altitudinal gradients. At present, it is still unclear whether there are some common patterns of morphological and genetic variation with altitude. Quercus aquifolioides Rehder & E.H. Wilson, which is an important ecological and economical endemic woody plant species, is widely distributed in the Yunnan and Sichuan provinces, Southwest China. Its large range of habitat across different altitudes implies strong adaptation to different environments, although it is mainly restricted to sunny, south facing slopes. It plays a very important role in preventing soil erosion, soil water loss and regulating climate, as well as in retaining ecological stability. In this paper, we tried to understand the altitudinal pattern of morphological and genetic variation along altitudinal gradients through the experiments of leaf morphological and physiological responses, microsatellite analysis and AFLP markers. In leaf morphological and physiological responses experiment, we measured leaf morphology, nitrogen content and carbon isotope composition (as an indicator of water use efficiency) of Q. aquifolioides along an altitudinal gradient. We found that these leaf morphological and physiological responses to altitudinal gradients were non-linear with increasing altitude. Specific leaf area, stomatal length and index increased with increasing altitude below 2,800 m, but decreased with increasing altitude above 2,800 m. In contrast, leaf nitrogen content per unit area and carbon isotope composition showed opposite change patterns. Specific leaf area seemed to be the most important parameter that determined the carbon isotope composition along the altitudinal gradient. Our results suggest that near 2,800 m in altitude could be the optimum zone for growth and development of Q. aquifolioides, and highlight the importance of the influence of altitude in research on plant physiological ecology. Genetic variation and differentiation were investigated among five natural populations of Q. aquifolioides occurring along an altitudinal gradient that varied from 2,000 to 3,600 m above sea level in the Wolong Natural Reserve of China, by analyzing variation at six microsatellite loci. The results showed that the populations were characterized by relatively high intra-population variation with the average number of alleles equaling 11.33 per locus and the average expected heterozygosity (HE) being 0.779. The amount of genetic variation varied only little among populations, which suggests that the influence of altitude factors on microsatellite variation is limited. However, there is a significantly positive correlation between altitude and the number of low-frequency alleles (R2=0.97, P < 0.01), which indicates that Q. aquifolioides from high altitudes has more unique variation, possibly enabling adaptation to severe conditions. F statistics showed the presence of a slight deficiency of heterozygosity (FIS=0.136) and a low level of differentiation among populations (FST=0.066). The result of the cluster analysis demonstrates that the grouping of populations does not correspond to the altitude of the populations. Based on the available data, it is likely that the selective forces related to altitude are not strong enough to significantly differentiate the populations of Q. aquifolioides in terms of microsatellite variation. To further elucidate genetic variation pattern of Q. aquifolioides populations under sub-alpine environments, genetic variation and differentiation were investigated along altitudinal gradients using AFLP markers. The altitudinal populations with an average altitude interval of 400 m, i.e. WL1, WL2, WL3, WL4 and WL5, correspond to the altitudes 2,000, 2,400, 2,800, 3,200 and 3,600 m, respectively. Our results were as follows: (i) decreasing genetic variation (ranging from 0.253 to 0.210) and increasing genetic differentiation with altitude were obtained from the WL2 to the WL5 population; (ii) the WL1 population showed the lowest genetic variation (HE = 0.181) and the highest genetic differentiation (average FST = 0.0596) with the other four populations; (iii) the positive correlation was obtained using Mantel tests between genetic and altitude distances except for the WL1 population. Our results suggest that altitudinal gradients may have influenced the genetic variation pattern of Q. aquifolioides populations to some extent. In addition, habitat environments (unfavorable wet and hot conditions) and human disturbances (burning, grazing and felling) were possible influencing factors, especially to the low-altitude WL1 population. The present study shows that there were close correlations between morphological features and carbon isotope composition in our data. This indicates that a coordinated plant response modified these parameters simultaneously across different altitudes. Around 2,800 m altitude there seems to be an optimum zone for growth and development of Q. aquifolioides, as indicated by thinner leaves, larger stomata and more negative d13C values. All available evidence indicates altitudinal gradients may have influenced the genetic variation pattern of Q. aquifolioides to some extent. Decreasing genetic variation and increasing genetic differentiation with altitude was obtained except for the WL1 population. And the environment of habitats and human disturbances were also contributing factors, which impact genetic variation pattern, especially to the low-altitude WL1 population.

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.

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.

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.

克隆植物东方草莓对异质生境的适应对策

克隆植物被认为比非克隆植物更宜于利用异质性环境。在复杂的空间异质环境中，克隆植物可能形成了各种有效利用环境异质性的适应对策。对于克隆植物适应机制的研究，前人已做了大量的工作，特别是从形态和生物量分配等方面对简单异质生境下克隆植物的克隆整合和克隆分工进行了详细的研究。本研究以分布广泛的克隆植物东方草莓（Fragaria orientalis）作为研究对象，应用野外调查和实验生态学方法，采用多对比度单资源模型和不同向双资源模型，从形态和生理生态的角度，研究复杂异质生境下克隆植物的整合和分工及其耗益问题，分析不同类型的生境对克隆植物整合和分工的修饰作用，进而探讨克隆植物对异质生境的适应策略。克隆构型和分株种群特征是植物克隆生长及其生态适应对策研究的基本内容。本文通过野外调查，研究在不同光照条件下东方草莓克隆构型、分株种群特征以及点分布格局。结果表明：东方草莓的克隆构型随光照发生相应的变化，低光照下其匍匐茎节间长和分枝角度均增大而分枝强度减小；随光照减弱，东方草莓分株种群的生物量、根冠比和分株种群密度显著降低；不同光照下东方草莓分株均以随机分布为主但不同尺度下有所差异，其分布格局强度依次为旷地<林缘<林下。结合克隆植物对资源的利用对策，探讨了克隆构型和分株种群特征以及分布格局随环境条件变化的生态适应意义。不同生境斑块条件下克隆植物可能采取不同的适应对策。采用盆栽实验，研究不同水分对比度下克隆整合及其生理生态特征，并对单向和交互资源中东方草莓的克隆整合做了对比研究。结果显示：高的水分对比度能够促进东方草莓的克隆整合，并能刺激相连分株增加光合作用，东方草莓体内的氧化—抗氧化系统也II随对比度做出相应的反应。耗-益分析表明胁迫分株的受益是以供给分株的损耗为代价的，但从克隆片段总体来说是受益的。单向资源中东方草莓生长的绝对值高于交互资源，但耗-益分析表明生长于交互资源下东方草莓的克隆整合获益大于生长于单向资源下东方草莓的克隆整合获益。长期生长于特定生境的克隆植物，在进化过程中其克隆整合和克隆分工在对资源异质性的适应策略方面可能有所侧重。采用盆栽实验对来自不同海拔梯度的东方草莓的克隆整合和克隆分工对异质资源的适应对策进行了研究。实验结果表明，来自高海拔的东方草莓可塑性较差。来自两个海拔的东方草莓对切断匍匐茎的表现有所差异，总体上切断匍匐茎对来自高海拔的东方草莓影响更大些。另外，来自高海拔的东方草莓表现出更高的克隆分工。IIIClonal plants are known to be more suitable for the habitats of heterogeneousresources than nonclonal plants, perhaps due to their well developed adaptivestrategies to environmental heterogeneity. Many studies have been done on theadaptive mechanisms of clonal plants, especially on the clonal integration anddivision of labor with morphology and biomass allocation under simpleheterogeneous habitats. Based on field surveys, laboratory experiments, multi-contrastunidirectional resource model and reciprocal resource model, Fragaria orientalis, aRosaceae stoloniferous herb that widely distributes in China, was used to study thisplant’s morphological and physiological responses to complicated heterogeneoushabitats in terms of its clonal integration, division of labor and cost-benefit, as well astheir modifications by different habitats, so as to better understand the adaptivestrategies of clonal plants under heterogeneous environments.Clonal architecture and ramet population characteristics are of the major concernin the studies on growth and adaptive strategies of clonal plants. Clonal architecture,ramet population characteristics and spatial point pattern of F. orientalis underdifferent light intensity were studied with field observations. The results showed that,clonal architecture changed with light availability: Internode-lengths and branchangels of stolons were larger while branch intensities were smaller under lower lightintensity than those under higher light intensity; Biomass of ramet population,root-shoot ratio and density of ramet population decreased significantly with reduce oflight intensity; Under all light intensities, spatial pattern of ramets was mainlyrandomly distributed but it changed with different scales, with pattern intensity as:open space < forest edge < understory. Adaptation significance of the clonal architecture, the ramet population characteristics and the spatial pattern changing withdifferent environments was discussed according to these results.Clonal plants may take different adaptive strategies under different patches. Withpot culture, clonal integration and physiological parameters of F. orientalis underdifferent water contrasts were studied, and clonal integration under unilateralresources and reciprocal resources were also compared. The results suggested that,high water contrast improve the clonal integration of F. orientalis and increase thephotosynthesis of connected ramets. Oxidative and antioxidative system of F.orientalis also responded with changing water contrasts. According to cost-benefitanalysis, the drought-stressed ramets obtained benefits from the connectedwell-watered ramets, and as a whole, the clonal fragment could also get benefits.Growth of F. orientalis in homogeneous resources was better than that inheterogeneous resources, but the whole plant got more benefit through clonalintegration in heterogeneous resources than in homogeneous resources.Pot culture experiments were also used to study the adaptive strategies inutilizing heterogeneous resources by the plant populations from different altitudes.The results showed that, F. orientalis from alpine zones were shorter and lessexpanded with poorer clonal plasticity than those from middle mountains. F.orientalis from two different altitudes showed different responses to stolon severing,and as a whole, stolon severing had more influence on F. orientalis from alpine zones.In addition, F. orientalis from alpine zones exhibited higher division of labor, whichsuggested that clonal plants from different habitats develop their own adaptivemechanisms in their clonal integration and division of labor in response toenvironmental heterogeneity.

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.