Étude comparative des propagules extraracinaires et intraracinaires du champignon mycorhizien Glomus irregulare

La germination des spores est une étape essentielle dans le cycle de vie de la majorité des champignons filamenteux. Les champignons mycorhiziens à arbuscules (CMA) forment un certain nombre de propagules infectieuses différentes qui augmentent leur potentiel à coloniser les racines. Parmi elles se trouvent les spores extraracinaires et intraracinaires. La paroi cellulaire des spores joue un rôle majeur dans la survie de ces propagules en étant une barrière physique et osmotique. Puisque une cellule peut faire des ajustements considérables dans la composition et la structure de sa paroi, en réponse aux conditions environnementales, il est possible que les parois des spores intraracinaires et extraracinaires montrent des propriétés mécaniques et osmotiques différentes affectant leur germination et leur survie. Pourtant, contrairement à la connaissance de la génétique moléculaire et de la formation de la paroi cellulaire des CMA, peu d’information est disponible au sujet de ces propriétés mécaniques. Les informations sur la germination des CMA dans des conditions hypertoniques sont aussi rares, et les modèles expérimentaux ne séparent généralement pas les effets directs de la forte pression osmotique externe sur la germination des champignons et les effets attribuables aux plantes. Cette étude avait pour but de répondre à deux importantes séries de questions concernant le comportement des spores mycorhiziennes. Nous avons d'abord déterminé la relation entre la composition de la paroi cellulaire, la structure et les propriétés mécaniques du champignon modèle Glomus irregulare (isolat DAOM 197198). La micro-indentation a été utilisée pour mesurer quantitativement les propriétés mécaniques de la paroi cellulaire. La composition (contenu de chitine et de glomaline) de la paroi cellulaire a été quantifiée par immunofluorescence tandis que la microscopie optique a été utilisée pour mesurer l'épaisseur de la paroi cellulaire. La densité locale en glomaline et l’épaisseur de la paroi étaient significativement plus élevées pour les parois des spores extraracinaires alors que la densité locale en chitine et la rigidité n’ont pas montré de variations entre les spores extraracinaires et intraracinaires. La grande variabilité dans les paramètres étudiés nous a empêchés de cibler un facteur principal responsable de la force totale de la paroi lors de la compression. La diminution des concentrations de chitine et de glomaline a été corrélée à l'évolution de la paroi du champignon au cours de son cycle de vie. On a aussi observé une composition différentielle des couches de la paroi: les polymères de chitine et de glomaline furent localisés principalement dans les couches externes et internes de la paroi, respectivement. Dans la deuxième partie de notre travail, nous avons exploré les effets directs d'engrais, par rapport à leur activité de l'eau (aw), sur la germination des spores et la pression de turgescence cellulaire. Les spores ont été soumises à trois engrais avec des valeurs de aw différentes et la germination ainsi que la cytorrhyse (effondrement de la paroi cellulaire) des spores ont été évaluées après différents temps d'incubation. Les valeurs de aw des engrais ont été utilisées comme indicateurs de leurs pressions osmotiques. L'exposition des spores de Glomus irregulare au choc osmotique causé par les engrais dont les valeurs de aw se situent entre 0,982 et 0,882 a provoqué des changements graduels au niveau de leur cytorrhyse et de leur germination. Avec l'augmentation de la pression de turgescence externe, la cytorrhyse a augmenté, tandis que le taux de germination a diminué. Ces effets ont été plus prononcés à des concentrations élevées en éléments nutritifs. La présente étude, bien qu’elle constitue une étape importante dans la compréhension des propriétés mécaniques et osmotiques des spores de CMA, confirme également que ces propriétés dépendent probablement de plusieurs facteurs, dont certains qui ne sont pas encore identifiés.

Glomus intraradices and Gigaspora margarita arbuscular mycorrhizal associations differentially affect nitrogen and potassium nutrition of Plantago lanceolata in a low fertility dune soil

Two controlled microcosm experiments aimed at a critical re-assessment of the contributions of divergent arbuscular mycorrhizal (AM) fungi to plant mineral nutrition were established that specifically targeted Plantago lanceolata–Glomus intraradices (B.B/E) and –Gigaspora margarita (BEG 34) symbioses developed in a native, nutrient limited, coastal dune soil. Plant tissue nitrogen (N), phosphorus (P) and potassium (K) status as well as plant growth parameters and levels of mycorrhizal colonization were assessed at harvest. In addition to the general well-established mycorrhizal facilitation of P uptake, the study was able to demonstrate a G. intraradices-specific contribution to improved plant nitrogen and potassium nutrition. In the two respective experiments, G. intraradices-inoculated plants had 27.8% and 40.8% more total N and 55.8% and 23.3% more total K when compared to Gi. margarita inoculated counterparts. Dissimilar overall contribution of the two isolates to plant nutrition was identified in AM-genus specific differences in plant tissue N:P:K ratios. G. intraradices inoculated and non-mycorrhizal plants generally exhibited N:P:K ratios indicative of P limitation whereas for Gi.margarita mycorrhizal plants, corresponding ratios strongly implied either N or K limitation. The study provides further evidence highlighting AM functional biodiversity in respect to plant nutrient limitation experienced by mycorrhizal P. lanceolata in an ecologically relevant soil system.

Sobrevivência de Xanthomonas axonopodis pv. manihotis em manipueira sob condições ambientais

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Glomus clarum e G. etunicatum: cultivo em solo e aeroponia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aspergillus niger e Glomus clarum incrementam a disponibilidade de fósforo em Latossolos sob Urochloa brizantha

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Transcriptome and Functional Analysis of Carotid Body Glomus Cells

The carotid body (CB) is a major arterial chemoreceptor containing glomus cells that are activated by changes in arterial blood contents including oxygen. Despite significant advancement in the characterization of their physiological properties, our understanding on the underlying molecular machinery and signaling pathway in CB glomus cells is still limited.

To overcome these limitations, in chapter 1, I demonstrated the first transcriptome profile of CB glomus cells using single cell sequencing technology, which allowed us to uncover a set of abundantly expressed genes, including novel glomus cell-specific transcripts. These results revealed involvement of G protein-coupled receptor (GPCR) signaling pathway, various types of ion channels, as well as atypical mitochondrial subunits in CB function. I also identified ligands for the mostly highly expressed GPCR (Olfr78) in CB glomus cells and examined this receptor’s role in CB mediated hypoxic ventilatory response.

Current knowledge of CB suggest glomus cells rely on unusual mitochondria for their sensitivity to hypoxia. I previously identified the atypical mitochondrial subunit Ndufa4l2 as a highly over-represented gene in CB glomus cells. In chapter 2, to investigate the functional significance of Ndufa4l2 in CB function, I phenotyped both Ndufa4l2 knockout mice and mice with conditional Ndufa4l2 deletion in CB glomus cells. I found that Ndufa4l2 is essential to the establishment of regular breathing after birth. Ablating Ndufa4l2 in postnatal CB glomus cells resulted in defective CB sensitivity to hypoxia as well as CB mediated hypoxic ventilatory response. Together, our data showed that Ndufa4l2 is critical to respiratory control and the oxygen sensitivity of CB glomus cells.

Composite Medicago truncatula plants harbouring Agrobacterium rhizogenes-transformed roots reveal normal mycorrhization by Glomus intraradices

Composite plants consisting of a wild-type shoot and a transgenic root are frequently used for functional genomics in legume research. Although transformation of roots using Agrobacterium rhizogenes leads to morphologically normal roots, the question arises as to whether such roots interact with arbuscular mycorrhizal (AM) fungi in the same way as wild-type roots. To address this question, roots transformed with a vector containing the fluorescence marker DsRed were used to analyse AM in terms of mycorrhization rate, morphology of fungal and plant subcellular structures, as well as transcript and secondary metabolite accumulations. Mycorrhization rate, appearance, and developmental stages of arbuscules were identical in both types of roots. Using Mt16kOLI1Plus microarrays, transcript profiling of mycorrhizal roots showed that 222 and 73 genes exhibited at least a 2-fold induction and less than half of the expression, respectively, most of them described as AM regulated in the same direction in wild-type roots. To verify this, typical AM marker genes were analysed by quantitative reverse transcription-PCR and revealed equal transcript accumulation in transgenic and wild-type roots. Regarding secondary metabolites, several isoflavonoids and apocarotenoids, all known to accumulate in mycorrhizal wild-type roots, have been found to be up-regulated in mycorrhizal in comparison with non-mycorrhizal transgenic roots. This set of data revealed a substantial similarity in mycorrhization of transgenic and wild-type roots of Medicago truncatula, validating the use of composite plants for studying AM-related effects.

Reação de variedades de mandioca (Manihot esculenta Crantz) a Xanthomonas axonopodis pv. manihotis.

O presente trabalho teve como objetivo avaliar 26 materiais de mandioca quanto à resistência a bacteriose em casa-de-vegetação. Plantas com 2 a 3 pares de folhas foram inoculadas com dois isolados de Xanthomonas axonopodis pv. manihotis (Xam) através da pulverização da suspensão bacteriana na face inferior das folhas. As avaliações da severidade da doença foram realizadas aos 4, 6, 8, 11, 13 e 15 dias após a inoculação do patógeno. O ensaio foi montado em esquema fatorial 2 x 26 (2 isolados x 26 variedades) e o delineamento foi em blocos casualizados com 3 repetições. Todos os materiais avaliados apresentaram sintomas característicos da bacteriose. No entanto, as variedades EAB 675, Inajá- PA, Orana, 34 Pretinha-3 e Pretona Erecta apresentaram menor severidade da doença, não apresentando diferença significativa quanto a virulência do patógeno. A variedade 37 Pretinha 4 se apresentou como mais suscetível para os dois isolados. Os isolados em estudo apresentaram variabilidade quanto à agressividade, sendo o isolado Xam P.225 o mais virulento.

Growth responses of sugarcane to mycorrhizal spore density and phosphorus rate

Arbuscular mycorrhizal (AM) fungi, commonly found in long-term cane-growing fields in northern Queensland, are linked with both negative and positive growth responses by sugarcane (Saccharum spp.), depending on P supply. A glasshouse trial was established to examine whether AM density might also have an important influence on these growth responses. Mycorrhizal spores (Glomus clarum), isolated from a long-term cane block in northern Queensland, were introduced into a pasteurised low-P cane soil at 5 densities (0, 0.06, 0.25, 1, 4 spores/g soil) and with 4 P treatments (0, 8.2, 25, and 47 mg/kg). At 83 days after planting, sugarcane tops responded positively to P fertilizer, although responses attributable to spore density were rarely observed. In one case, addition of 4 spores/g led to a 53% yield response over those without AM at 8 mgP/kg, or a relative benefit of 17 mg P/kg. Root colonisation was reduced for plants with nil or 74 mg P/kg. For those without AM, P concentration in the topmost visible dewlap (TVD) leaf increased significantly with fertiliser P (0.07 v. 0.15%). However, P concentration increased further with the presence of AM spores. Irrespective of AM, the critical P concentration in the TVD leaf was 0.18%. This study confirms earlier reports that sugarcane is poorly responsive to AM. Spore density, up to 4 spores/g soil, appears unable to influence this responsiveness, either positively or negatively. Attempts to gain P benefits by increasing AM density through rotation seem unlikely to lead to yield increases by sugarcane. Conversely, sugarcane grown in fields with high spore densities and high plant-available P, such as long-term cane-growing soils, is unlikely to suffer a yield reduction from mycorrhizal fungi.

Field inoculation with arbuscular-mycorrhizal fungi overcomes phosphorus and zinc deficiencies of linseed (Linum usitatissimum) in a vertisol subject to long-fallow disorder

Long-fallow disorder is expressed as exacerbated deficiencies of phosphorus (P) and/or zinc (Zn) in field crops growing after long periods of weed-free fallow. The hypothesis that arbuscular-mycorrhizal fungi (AMF) improve the P and Zn nutrition, and thereby biomass production and seed yield of linseed (Linum usitatissimum) was tested in a field experiment. A factorial combination of treatments consisting of +/- fumigation, +/- AMF inoculation with Glomus spp., +/- P and +/- Zn fertilisers was used on a long-fallowed vertisol. The use of such methods allowed an absolute comparison of plants growing with and without AMF in the field for the first time in a soil disposed to long-fallow disorder. Plant biomass, height, P and Zn concentrations and contents, boll number and final seed yield were (a) least in fumigated soil with negligible AMF colonisation of the roots, (b) low initially in long-fallow soil but increased with time as AMF colonisation of the roots developed, and (c) greatest in soil inoculated with AMF cultures. The results showed for the first time in the field that inflows of both P and Zn into linseed roots were highly dependent on %AMF-colonisation (R-2 = 0.95 for P and 0.85 for Zn, P < 0.001) in a soil disposed to long-fallow disorder. Relative field mycorrhizal dependencies without and with P+Zn fertiliser were 85 % and 86 % for biomass and 68 % and 52 % for seed yield respectively. This research showed in the field that AMF greatly improved the P and Zn nutrition, biomass production and seed yield of linseed growing in a soil disposed to long-fallow disorder. The level of mycorrhizal colonisation of plants suffering from long-fallow disorder can increase during the growing season resulting in improved plant growth and residual AMF inoculum in the soil, and thus it is important for growers to recognise the cause and not terminate a poor crop prematurely in order to sow another. Other positive management options to reduce long fallows and foster AMF include adoption of conservation tillage and opportunity cropping.

Evaluación de enmiendas y microorganismos antagonistas para el manejo de pseudomonas solanacearum E.F. Smith en cultivo de tomate (Lycopersicon esculentum L.)

Se estudió el efecto de dos enmiendas y tres microorganismos como posibles factores supresívos y antagonistas respectivamente al agente causal de la marchitez bacteriana Pseudomonas solanacearum E.F.Srnlth. Los experimentos fueron conducidos en campo e invernadero en el Centro Agronómíco Tropical de Investigación y Enseñanza (CATIE), Turrialba, Costa Rica. Se establecieron en diseño de parcelas divididas con cuatro repeticiones en el campo y tres en el invernadero. Las parcelas principales se dispusieron en bloques completamente al azar. Se evaluaron tres tratamientos (compost comercial, cal dolomítica y un tratamiento sin enmiendas) en las parcelas principales y ocho tratamientos (Pseudomonas cepacia, Bacillus cereus y Glomus occultum solos y en combínación) en las subparcelas. Los tratamientos con enmiendas se asignaron a las parcelas principales, mientras que los tratamientos con antagonistas se asignaron a las subparcelas. Las variables evaluadas fueron incidencia y severidad de la enfermedad y área bajo la curva de progreso de la enfermedad (ABCPE). Se determinó el efecto de las enmiendas sobre las poblaciones de P. solanacearum en tres momentos. En el campo no hubo diferencias significativas en las varia~ bles evaluadas. Las poblaciones de P. solanocearum fueron reducidas significativamente en el suelo. En invernadero, las enmiendas redujeron significativamente la severidad de la enfermedad y el ABCPE. Los antagonistas no redujeron significativamente la incidencia y la severidad en el campo e invernadero.

Corpo carotídeo e hipertensão: alterações celulares e da matriz extracelular

O aumento de doenças cardiovasculares possui como fator primordial e, mais comum, o aumento da pressão arterial (PA). Esta, pode gerar complicações em outros órgãos e acarretar diversas patologias, podendo levar a morte. A hipertensão é uma síndrome multifatorial, cuja maior incidência ocorre em indivíduos obesos, sedentários e consumidores em excesso de bebidas alcoólicas e sal. O corpo carotídeo (CC) é um órgão quimiorreceptor localizado na bifurcação da artéria carótida, formado de estruturas básicas chamadas glomus. Cada glomus carotídeo é constituído de células tipo 1 envoltas por células tipo 2 ou sustentaculares. Este trabalho teve como objetivo analisar as alterações morfofuncionais que ocorrem no CC, causada por hipertensão arterial induzida pelo L-NAME, um inibidor da enzima óxido nítrico sintase. Para isso, o estudo utilizou 20 ratos Wistar divididos em dois grupos: controle (C) e L-NAME (LN). Após a administração de 40mg/kg/dia de L-NAME por 45 dias, o CC foi coletado. Observou-se aumento significativo da pressão arterial a partir da segunda semana de administração de L-NAME. Análise quantitativa mostrou uma redução no número de núcleos do glomus carotídeo e o aumento na área total do órgão no grupo LN. Não foi encontrado diferença significativa no número de núcleos totais do corpo carotídeo entre os grupos. Na análise morfológica do grupo LN, observamos a formação de vacúolos nas células tipo 1 do glomus, bem como uma redução do número total de núcleos das células de cada glomus carotídeo. A análise qualitativa sugeriu um aumento no número de fibras colágenas e fibras do sistema elástico na matriz extracelular e grânulos no grupo LN. Imunomarcações com anticorpo anti VEGF e NF-kB e nNOS mostram-se aumentadas e dispersas por todo CC no grupo LN em relação ao grupo C. Além disso, marcações para Substância-P também foram observadas em maior quantidade nas células tipo 1 do grupo LN. Quanto à marcação para PGP 9.5, houve a redução desta marcação caracterizada dentro do glomus carotídeo grupo LN comparado ao grupo C. O estudo sugere que o corpo carotídeo, em resposta à hipertensão induzida pela inibição da enzima óxido nítrico sintase, gera mudanças morfofisiológicas semelhantes as encontradas em hipóxia.

丛枝菌根真菌对异质性环境中克隆植物的影响

克隆植物同一基株的相连克隆分株或克隆片段常常生长在资源条件不同的斑块中，分株间形成克隆整合和克隆可塑性以及克隆分工等有效地获取必需资源的生态适应对策，提高在异质性斑块生境中的适合度，适应环境的异质性变化。但在以往的克隆植物生态学的理论研究中，为了研究的简化和方便，往往忽略了土壤中微生物的作用。丛枝菌根(Arbuscular mycorrhiza, AM)真菌是自然界中广泛存在的土壤微生物之一，可与大多数的高等植物形成共生菌根，影响植物的生长、发育及其在生态系统中的作用。 本文应用实验生态学方法，以蛇莓、狗牙根和白三叶为研究对象，在温室受控条件下，对异质养分斑块中的分株对接种AM真菌，探讨AM真菌对资源斑块中克隆植物的影响。 第一个实验设计单一磷养分斑块，以蛇莓(Duchesnea indica)和摩西球囊霉(Glomus mosseae)为研究对象，探讨丛枝AM真菌对克隆整合的影响。将蛇莓相连的两个分株，即分株对，分别种植在两个隔离的花盆中，各施以高磷和低磷营养液，保持或切断分株间匍匐茎连接，即间隔子，再将菌剂接种到低磷斑块中分株。结果发现间隔子状态和接菌处理都显著影响低磷斑块中蛇莓分株的根系生物量分配。对照处理中保持间隔子连接显著减少低磷斑块中分株生物量向根系的分配，接菌后这一差异显著减小。保持间隔子连接或接菌对高磷斑块中分株的根系生物量分配不显著。保持间隔子连接和接菌都显著增加低磷斑块分株的生物量在分株对生物量中所占比例，二者无显著交互作用。 第二个实验设计光照和养分斑块，以狗牙根(Cynodon dactylon)和摩西球囊霉为研究对象，探讨AM真菌对克隆植物非局域反应的影响。将狗牙根分株对的两个分株分别种植在两个花盆中，各施以光照强度与土壤养分交互斑块性环境条件，形成高养低光和高光低养斑块，保持或切断间隔子，再将菌剂接种到目标分株。结果发现对照处理中，间隔子状态显著影响分株的局域反应。高养斑块中保持间隔子连接的分株的根长显著大于间隔子断裂的分株的根长，高光斑块中保持间隔子连接的分株的根长显著小于间隔子断裂的分株的根长。高光斑块中保持间隔子连接的分株的叶面积显著大于间隔子断裂的分株的叶面积，间隔子状态对低光高养斑块分株的叶面积无显著影响。在低光高养斑块中，相对于间隔子断裂的分株，间隔子连接的分株将更多的生物量分配到根系，而在高光斑块中的分株则相反。这些都说明，无AM真菌侵染的情况下，狗牙根分株对的两个分株在实验中各自形成的克隆部分的分株形态反应都受到了克隆整合的作用，表现为非局域反应。接种AM真菌后，高光斑块中分株的根长和高养斑块中分株的叶面积在间隔子连接和断裂处理之间的差异显著减小。生物量分配的差异不受接菌的影响。对照处理中，高养斑块中间隔子连接的分株生物量和分株数显著高于间隔子断裂的分株，但高光斑块中分株之间无显著差异。接种AM真菌显著降低高养斑块中分株的生物量和分株数，对高光斑块中分株无显著影响。 第三个实验设计光照和养分交互斑块，以白三叶(Trifolium repens)和多种AM真菌为研究对象，探讨AM真菌及其多样性对克隆分工的影响。将间隔子连接(整合)或断裂(无整合)的白三叶分株对种植于光照强度和土壤养分交互斑块性资源条件下(即，高光低养和低光高养)，向分株对接种灭菌处理、单种或五种AM真菌的菌剂。结果发现，对照处理中，间隔子连接的分株对在光养交互斑块中与间隔子断裂的分株对相比较表现出克隆分工，即高光低养斑块中的分株的根系生物量分配增加，低光高养斑块中的分株的根系生物量分配减少。单菌处理没有影响对照处理中间隔子状态对分株对生物量分配的改变；多菌处理显著减小对照中生物量分配的改变；与单菌处理比较，多菌处理能显著减小生物量分配的改变。在高光低养斑块中，多菌处理显著抑制间隔子断裂分株的根生物量分配的增加。在低光高养斑块中，多菌处理完全抑制在对照处理中间隔子连接的分株的根生物量分配的增加。在对照处理中，间隔子连接分株的单叶面积、总叶面积、叶柄长、根长都与生物量分配趋势一致，表现出对丰富资源的特化。接菌处理能显著抑制这些形态指标的改变。多菌处理显著抑制这些指标的特化，并且抑制效果显著强于单菌处理。间隔子状态和AM真菌处理显著增加高光低养、低光高养斑块中分株及整个克隆片段的生物量和分株数。多菌处理抑制间隔子连接的克隆片段生物量和分株数增加。克隆片段的生物量和分株数在对照和单菌处理间无显著差异，在多菌处理中显著高于在单菌处理中。 以上三个实验说明，(1)AM真菌对克隆植物生长的影响与非克隆植物一样，受到植物种类和环境资源水平的影响；(2)AM真菌对异质性资源环境中克隆植物的影响由于植物不同而产生不同的效应；(3)提高AM真菌的多样性可能增强菌根对克隆植物的作用。 这些研究结果揭示出AM真菌与异质性环境中克隆植物整合作用、非局域反应和克隆分工作用的交互影响，表明克隆生长在生态系统中的重要性可由生物和非生物因素共同决定。

固氮树木丛枝菌根真菌(AMF)遗传多样性的研究

丛枝菌根是自然生态系统中分布最广的内生菌根，在促进植物生存与生长、植被恢复以及生物多样性保护等方面有着非常重要的作用。 随着现代分子生物学技术的不断发展，丛枝菌根真菌研究得到空前发展。大量DNA分析新技术在丛枝菌根真菌的分子遗传、分类鉴定、种间及种内亲缘关系、菌株持久性等方面得到应用，与传统菌根研究方法相比，表现出巨大的优越性。 本项研究利用分子生物学技术和研究方法对中国吉林长白山地区非豆科固氮植物以及东北地区固氮树木的丛枝菌根真菌DNA分子多态性及其与宿主植物之间的相互关系等进行初步研究，旨在利用分子生态学理论和研究方法揭示丛枝菌根真菌多样性及其与宿主植物之间相互适应和协同进化的一般规律，为更好地保护和利用这一重要的微生物资源提供理论依据。 通过比较与筛选，建立起丛枝菌根真菌痕量DNA快速、简便、高效的提取纯化方法——改良CTAB法。经PCR检测，所得DNA满足进一步研究的要求。 根据丛枝菌根真菌18s rRNA 小亚基核基因片段的特点，利用“科”特异性引物进行半巢式标记PCR (Labelled Primers-PCR，LP-PCR) 及单链构象多态性（Single-Stranded Conformation Polymorphism，SSCP）分析技术研究了长白山赤杨在属水平上表现出的多样性。另外，利用巢式PCR-RFLP技术，分别对来源于长白山不同海拔的四种赤杨菌根样品的AMF侵染情况及其系统进化进行了研究。利用AMF特异性PCR技术对我国东北地区四种非豆科树木和5种豆科树木菌根侵染情况和系统发育规律进行了研究 研究结果显示：赤杨根内AMF存在丰富的基因多样性。AMF的侵染有从宿主混乱性向宿主专一性发展的趋势。 长白山地区赤杨属植物至少有东北赤杨、西伯利亚赤杨和色赤杨三个树种在其“属”的水平上与共生的球囊霉科（Glomaceae）至少一个“种” 的丛枝菌根真菌，即根内球囊霉（Glomus intraradix），在“种”的水平上表现出不相关于宿主海拔高度的某种相互选择性。 东北赤杨AMF菌的宿主专一性水平最强，球囊霉属已成为东北赤杨的优势侵染类群；对于其余三种赤杨，AMF则出现宿主混乱现象。宿主因素比海拔因素对AMF侵染特异性的影响更为重要。 豆科与非豆科样本的混乱性都比较强，在特定植物和AMF属之间无特异侵染规律，相对来说，非豆科树木比豆科树木对于AMF的选择性要更强一些，更倾向于和球囊霉属与无梗孢囊霉属的AMF构建共生体。

固氮树木丛枝菌根真菌（AMF）遗传多样性的研究

丛枝菌根是自然生态系统中分布最广的内生菌根，在促进植物生存与生长、植被恢复以及生物多样性保护等方面有着非常重要的作用。 随着现代分子生物学技术的不断发展，丛枝菌根真菌研究得到空前发展。大量DNA分析新技术在丛枝菌根真菌的分子遗传、分类鉴定、种间及种内亲缘关系、菌株持久性等方面得到应用，与传统菌根研究方法相比，表现出巨大的优越性。 本项研究利用分子生物学技术和研究方法对中国吉林长白山地区非豆科固氮植物以及东北地区固氮树木的丛枝菌根真菌DNA分子多态性及其与宿主植物之间的相互关系等进行初步研究，旨在利用分子生态学理论和研究方法揭示丛枝菌根真菌多样性及其与宿主植物之间相互适应和协同进化的一般规律，为更好地保护和利用这一重要的微生物资源提供理论依据。 通过比较与筛选，建立起丛枝菌根真菌痕量DNA快速、简便、高效的提取纯化方法——改良CTAB法。经PCR检测，所得DNA满足进一步研究的要求。 根据丛枝菌根真菌18s rRNA 小亚基核基因片段的特点，利用“科”特异性引物进行半巢式标记PCR (Labelled Primers-PCR，LP-PCR) 及单链构象多态性（Single-Stranded Conformation Polymorphism，SSCP）分析技术研究了长白山赤杨在属水平上表现出的多样性。另外，利用巢式PCR-RFLP技术，分别对来源于长白山不同海拔的四种赤杨菌根样品的AMF侵染情况及其系统进化进行了研究。利用AMF特异性PCR技术对我国东北地区四种非豆科树木和5种豆科树木菌根侵染情况和系统发育规律进行了研究 研究结果显示：赤杨根内AMF存在丰富的基因多样性。AMF的侵染有从宿主混乱性向宿主专一性发展的趋势。 长白山地区赤杨属植物至少有东北赤杨、西伯利亚赤杨和色赤杨三个树种在其“属”的水平上与共生的球囊霉科（Glomaceae）至少一个“种” 的丛枝菌根真菌，即根内球囊霉（Glomus intraradix），在“种”的水平上表现出不相关于宿主海拔高度的某种相互选择性。 东北赤杨AMF菌的宿主专一性水平最强，球囊霉属已成为东北赤杨的优势侵染类群；对于其余三种赤杨，AMF则出现宿主混乱现象。宿主因素比海拔因素对AMF侵染特异性的影响更为重要。 豆科与非豆科样本的混乱性都比较强，在特定植物和AMF属之间无特异侵染规律，相对来说，非豆科树木比豆科树木对于AMF的选择性要更强一些，更倾向于和球囊霉属与无梗孢囊霉属的AMF构建共生体.