长雄野生稻内生菌的群落结构特征及其抗逆功能研究

Strong rhizomatousness is a key component of perenniality of Oryza longistaminata that contribute to competitiveness and perennial trait of the wild rice. At present, the sudies on O. longistaminata are focus on genetic research and mapping of gene controlling rhizomatousness, but the endophytes biodiversity and biofunctions is unclear. Studies of the biodiversity of the endophytes, the interaction of endophytes with their host and their function within their hosts are important to address the ecological relevance and evolution of O. longistaminata and guide the agricultural practice. In the project, an effort was taken to get insights into the endophytes of O. longistaminata from the ecosystem to molecular levels. Community structure and biodiversity of the endophytes in different tissues of O. longistaminata from 14 different afria countries will be analyse using MiSeq pyrosequencing, the dynamic change of endophytes community structure under different conditions will be determined by MiSeq analysis, the transmission of endophytes will be observed using the GFP-tagged strains. In addition to, the role of endophytes in plant abiotic stress tolerance will be estimated through assessing the efficiency of endophyte colonization of inoculated plants and the absence of endophytes in mock-inoculated controls. To study the endophytes in O. longistaminata with specical evolution and survival strategy will reveal the evolution and molecular mechanism in the plant micro-ecosystem.

发达的地下茎使得长雄野生稻具备优良的抗逆性和多年生的特性。目前国内外研究多集中于长雄野生稻地下茎相关基因的克隆，对其内生菌的研究尚无报道。挖掘长雄野生稻内生菌资源，分析植物与内生菌互作的分子机制，对于阐明长雄野生稻的进化生物学特征和农业实践生产具有重要意义。本项目以具有特殊进化历程和生存策略的长雄野生稻为材料，拟对其地下茎、根系及叶等组织的内生菌群落结构特征和增强宿主的抗逆性进行分析。通过MiSeq对源自14个非洲国家的长雄野生稻内生菌进行高通量测序，分析内生菌生物多样性和群落结构特征。利用MiSeq分析逆境胁迫下内生菌群落结构的动态变化，筛选具有促进宿主抗逆活性的内生菌，并观察其定殖过程。进一步，通过回接和消除长雄野生稻的内生菌，研究其提高宿主抗逆的作用机制。本研究不仅为揭示植物微生态系统的进化和植物-微生物互作的分子机制提供理论依据，而且为现代水稻遗传育种提供理论支持和实践基础。

全球气候变暖加剧干旱对农作物的危害，如何应对干旱对水稻的产量和品质的影响？除了节水灌溉、改善作物本身的抗旱能力等方式，通过改善水稻微生物来提高宿主抗旱成为一种新的解决方案。长雄野生稻具备抗旱、抗虫、抗病等优良性状，挖掘长雄野生稻微生物资源，分析植物与微生物的互作效应，对于阐明长雄野生稻的进化生物学特征和农业实践生产具有重要意义。本项目通过16s rRNA高通量测序，分析了长雄野生稻叶、茎、根和根系的微生物组。结果表明，长雄野生稻四个组织中Proteobacteria，Firmicutes 和Bacteroidetes都是优势菌，但四个组织的微生物群落结构存在显著差异(PERMANOVA, P<0.01)。干旱显著改变了长雄野生稻各组织的微生物群落结构和共发生网络特征。从水稻田分离的固氮共生菌（Raoultella terrigena和Sinorhizobium sp）具有溶磷、产IAA和铁载体等促生特性。水培、盆栽和田间试验表明，接种Raoultella terrigena和Sinorhizobium sp显著的提高了栽培稻中华11的根生物量、株高和光合效率，这种促生效应在缺氮环境下尤为显著。本项目表明野生稻是宝贵的微生物资源库，为挖掘野生稻微生物组提高栽培稻的产量和品质提供了理论依据和实践价值。