水稻根系分泌物与根际微生物在病害防控中的相互作用机制研究

Rice disease is one of the most serious disasters in rice production. The application of Plant Growth-Promoting Rhizobacteria(PGPR) is one of effective ways to improve the disease resistance in rice. The colonization of PGPR is necessary for PGPR plays a role in promoting plant growth and resisting pathogens. The colonization ability of PGPR is mainly regulated by root exudates, and different kinds of rice have secret different components of root exudates. Root exudates can also influence disease inhibition ability by regulating rhizosphere microbial community in soil. However, the mechanism involved in root exudates and rhizosphere microorganisms has not been well studied. In this research, we will screen out several PGPR strains from rice soil and the root exudates of rice will be collected and analyzed by Gas Chromatography-Mass Spectrometer (GC-MS). Thereby we can identify the key compound(s) in root exudates that influences the colonization ability of PGPR and regulates rhizosphere microbial community. We expect to explain the mechanism of root exudates in improving disease resistance of rice. The key compond(s) in root exudates can be used as new target traits in the rice breeding program. In addition, the results also provide a theoretical basis for improvement of rice quality and yield promoted by PGPR.

水稻病害是水稻生产过程中最严重的灾害之一，严重影响水稻的产量。向土壤中施用植物根际促生菌是提高水稻抗病能力的有效途径之一，而促生菌发挥促生和生防功能的前提是在根际成功定殖。促生菌的根际定殖能力主要受根际分泌物调控，不同品种水稻的根系分泌物组成存在差异，且根系分泌物能够通过调控根际微生物群落组成来影响土壤的抑病能力。然而根系分泌物与根际微生物互作的机制并未得到深入研究。本项目研究水稻根际微生物的组成，从中筛选具有显著促进水稻生长和增强抗病能力的促生菌，并从根系分泌物的角度，鉴定提高促生菌定殖能力，调控健康根际微生物群落的活性组分并研究作用机理。该研究有助于深入认识根系分泌物在提高水稻抗病中的机理，筛选到的根系分泌物活性组分在水稻设计育种过程中具有实用意义，同时为促生菌提高水稻品质和产量提供理论依据。

稻瘟病菌引起的稻瘟病是目前世界上水稻种植区域最为严重的病害之一。植物根际促生菌可通过诱导植物诱导系统抗性来提高植物对生物胁迫的抗性。申请人以感病品种日本晴和抗病品种大力为材料，研究发现两者根系分泌物存在差异，但根际微生物群落结构并未显著发生变化，两者在稻瘟病抗性上的差异与根际微生物群落关系较小。同时从大力根际筛选到2株促生菌，根系分泌物能够促进其生物膜形成，根际定植后通过提高水稻光合作用、增加抗氧化酶减轻活性氧对细胞的毒害、产生IAA激活水稻IAA信号途径直接促进水稻生长激活下游防御基因、激活JA/ET信号途径、诱导稻瘟病抗性基因表达等方式提高水稻抗稻瘟病能力。本研究有助于深入认识微生物在水稻抗病过程中的作用。