内蒙古针茅草原AM真菌多样性与区系研究

Arbuscular mycorrhizal fungi (Glomeromycota) colonize the roots of about majority of vascular plant species, and can increase uptake of some mineral nutrients, improve drought resistance, and provide pathogen protection of host plants. Different AMF communities induce different growth response in plants playing a potential role to determine ecosystem variability and productivity. The distribution of AMF were affected by the plant species, soil type, climate and other environmental factors. Much more studies are focus on the AMF diversity and its function, but the classification, mycobiota and biogeogrophy have not been research in the Mongolia steppe. In this study, the population, species and genetics diversity of AMF will be investigated in different Stipa steppes in Inner Mongolia area. The classification, conponent of community, genus and family, and biogeogrophic characteristic of AMF will be studied and analysised. The correlationship between the species and genetic diversity of AMF, with the soil microorganisms and soil factors will be calculated and analysized. The biogeographical distribution law of AM fungi will be investigated , and provide theoretical basis for understanding the principle of the co-evolutionary relationship between the AMF mycobiota with the host plant. This has important role for the protection and utilization of AM fungi and it host plants resource.

丛枝菌根真菌(Arbuscular mycorrhizal fungi，AMF)广泛分布于草原生态系统，分类归属球囊霉门（Glomeromycota)；侵入植物根系形成丛枝菌根，影响寄主植物的养分吸收、生长发育及抗逆性，影响植物种间关系、植物群落演替与生态系统生产力。AM真菌的分布受寄主、土壤类型、气候环境各因素的影响，其多样性和功能被广泛关注，但分类、区系与生物地理分布的研究尚未深入。本项目拟以内蒙古地带性草原植被中最具典型性的针茅草原为对象，研究①群落AM真菌的物种多样性和遗传多样性；②不同针茅草原AM真菌种群、科属分布和生物地理分布特征；③AM真菌与土壤微生物的多样性以及土壤因子的相关性；④探索AM真菌区系、生物地理学研究的方法和理论。为阐述针茅草原植被发育与AM真菌的协同进化关系、以及AM真菌和寄主植物的资源保护和利用提供理论依据。

项目以分布于内蒙古中温带地区替代分布的贝加尔针茅、大针茅、克氏针茅、短花针茅、沙生针茅、石生针茅、戈壁针茅种群及草原为研究对象，通过孢子形态镜检测定AM真菌物种多样性以及高通量测序确定针茅植物根围土壤微生物（AMF）遗传多样性。结果显示，针茅根围土壤AM真菌无性孢子物种群落以Glomeraceas、Acaulosporaceae、Entrophpsporoceae、Claroideogomeraceae、Gigasporaceae及Diversisporaceae科的种类为主，高通量测序注释出AM真菌 5目9科14（3个未知）属的83种；球囊霉属（Glomus）优势度最高，在种水平和OTU水平上的相对丰度分别为73.49%和37.65%。随针茅种群替代，球囊霉属的相对丰度较稳定，而类球囊霉属（Paraglomus）的相对丰度变化明显。7个针茅种群植物根围土壤样本中共鉴定出细菌37门99纲267目463科910属，放线菌门（Actinobacteria）、变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）、绿弯菌门（Chloroflexi）的相对丰度占比较大为优势菌门。贝加尔针茅根围土壤细菌群落生物标记物高于其他针茅种群。随针茅种群替代分布，绿弯菌门（Chloroflexi）、 变形菌门（Proteobacteria）和红色杆菌属（Rubrobacter）的相对丰度变化显著且具有一定规律性，细菌群落总体上具有高多样性、低均匀度和低丰富度或低多样性、高均匀度和高丰富度的根围分布特征。另外，从锡林郭勒典型草原的大针茅根部分离鉴定出内生真菌14种，子囊菌门（Ascomycota）12种、担子菌门（Basidiomycota）2种；Fusarium、Trichoderma和Penicillium是优势属， Darksidea为常见属；芳香镰孢菌（Fusarium redolens）和同色镰刀菌（F. concolor）为优势类群，占总数的46.66%。针茅根围土壤微生物群落与生态环境因子之间具有一定的关联，随针茅种群的替代分布，土壤AM真菌、细菌的群落结构、物种组成和多样性变化主要受水热因子和植被覆盖度的驱动, 而且细菌群落还受到土壤pH的影响。表明AM真菌及其他微生物协同中温带地区针茅植物种群的替代分布而适应环境。