东乡野生稻内生菌群构特征及其与宿主抗逆相关性研究

Endophytes have broad application prospects while used as green and efficient biological fertilizer or pesticides as their abundant biodiversity and the function in promoting growth and improving stress resistance of host plant. Meanwhile, their application in the breeding has become a new development direction for crop genetics breeding.Dongxiang wild rice (DW), one of the most northern species of Oryza rufipogon in the world endemic in Dongxiang county, Jiangxi province, possess strong tolerance to cold, drought, barren and disease, etc. It would be destined to have more multifunctional and high potential endophytes in DW as an endemic plant with good stress-tolerance, and these endophytes can play an important role in forming stress-tolerance characteristics of DW. However, so far, there is no study focus on the endophytes of DW. In present study, the community diversity and structural dynamic will be investigated scientifically by using the culture-dependent and culture-independent methods, and the endophytes with functions of growth promotion and stress resistance will also be isolated from the DW in three natural populations. Furthermore, the pot culture experiments of functional endophytes were applied to discuss the relationship between endophytes diversity and the stress (cold, drought, barren and disease) resistant capability of host plant. According to present study, we can not only elucidate the community diversity and structural dynamic of endophytes and isolate more multifunctional, high potential and novel endophytes from DW, but also demonstrate the relationship between stress resistant capabilities of host plant and endophytes of DW. The results also can make an important guidance to modern genetics breeding of crop.

植物内生菌生物多样性丰富，具有促生、提高宿主抗逆性等功能，用作绿色、高效生物化肥或农药前景广阔，同时其在育种中的应用亦成为作物遗传育种新的发展方向。东乡野生稻(简称东野)为江西特有、世界分布最北的普通野生稻，具有耐寒、抗旱、耐贫瘠与抗病等丰富抗逆特性。作为一种抗逆且地区特有植物，其不仅可能蕴含丰富内生菌群，而且内生菌群可能与其抗逆性形成相关。迄今，东野内生菌相关研究未见报道。本项目以3个东野原位居群为对象，结合培养法与非培养法，系统开展其内生菌群落多样性和结构动态研究，筛选具促生、抗逆生物活性的内生菌。在此基础上，将具潜在功能内生菌用于栽培稻盆栽实验，以探讨东野内生菌对宿主抗逆（耐贫瘠、抗旱、抗寒及抗病）相关性。本研究不仅可系统阐明东野内生菌群落多样性及其结构动态规律，筛选具多功能、新功能和高效能的内生菌株或新菌种，揭示内生菌菌群对东野抗逆性的贡献，而且对于现代水稻遗传育种具有重要指导意义

本项目以江西特有、世界分布最北的普通野生稻——东乡野生稻原位居群为对象，系统开展其内生菌群落多样性和结构动态研究，发现东乡野生稻内生细菌、放线菌和真菌生物多样性丰富，且随着生长期和组织器官的不同呈现明显规律性变化。东乡野生稻内生细菌、放线菌和真菌的分离数量和生物多样性均随着生长期呈上升趋势，高低顺序为成熟期、抽穗期、秧苗期；不同组织器官中内生细菌、放线菌生物多样性高低顺序为种子、根、茎、叶，而内生真菌为叶、茎、根、种子。内生细菌的优势菌属为芽孢杆菌属、泛菌属、微杆菌属及短小杆菌属；内生放线菌优势菌属为链霉菌、小单孢菌，其中稀有放线菌比例较高（46%）。采用多相分类法鉴定了1株链霉菌（Streptomyces dongxiangnensis sp. nov.）、2株小单孢菌新种（Micromonospora isatinica sp. nov., M. dongxiangnensis sp. nov.）。不同生长期和不同组织器官内生真菌群落构成差异明显，且内生真菌优势属为Aspergillus、Penicillium、Trichoderm。开展了促生、抗逆生物活性微生物的大规模筛选，筛选出大量具有固氮、溶磷、产IAA、分泌铁载体和产ACC脱氨酶的内生细菌，以及抑制病原细菌和植物病原真菌的内生放线菌和内生真菌，并从2株内生放线菌中分离到尼日利亚菌素、靛红等8个活性化合物。在此基础上，选择了其中一些具有生物活性的内生细菌开展栽培稻盆栽实验，发现其可有效促进栽培稻的生长和提升其抗逆性能，初步验证了东乡野生稻内生菌有助于宿主抗逆特性的形成。本研究不仅系统阐明东野内生菌群落多样性及其结构动态规律，筛选具生物活性的内生微生物，这为利用内生菌开发生物化肥、生物农药以及将其应用于水稻遗传育种奠定了良好的基础。