间作系统中种间互作调控玉米根际微生物抵御病害的效应和机制

Upon attack by pathogen, insect and other biotic or abiotic stress, plants are able to recruit beneficial microorganisms to defense stress. Many reports demonstrated that the diversity of rhizosphere microbes associated with crop roots is higher in intercropping system than in monoculture system. To date, however, the effective and mechanism mediates the plant root-rhizosphere microbiome interaction for disease control in intercropping system remain to be elucidated. There are many interspecific interactions involved in intercropping system, including crop-crop, crop-host and nonhost pathogen, and so on. Whether these interspecific interactions can benefit for crops to recruit microorganisms from soil for protection against pathogen infections is little attention. Our previous experiments suggested that the expression levels of plant hormone signal pathways and the accumulation of defense compound BXs in maize roots and shoots were induced when maize roots triggered by the elicitors from the pathogen and root exudates from the neighboring pepper plants, which could then enhance its resistance. The aim of this study is to decipher the rhizosphere microbiome to identify disease-suppressive microbes recruit by maize roots under interspecific interaction conditions and to unravel the mechanisms by which they mediate the change of microbial communities in the rhizosphere through modifying root exudates profile. These studies will benefit us to understand the feedback mechanism of plant-rhizosphere microbiome-pathogen for disease suppression on community level and to develop new model agricultural techniques to control disease. It is also benefit us to understand the genetic mechanism of maize recruiting beneficial microorganism through root exudates and to breed new variety for disease management.

植物在受到病原菌、害虫及其他生物或非生物因子胁迫后可以通过根系分泌物募集有益微生物帮助自己抵御胁迫。众多研究发现作物间作能增加土壤微生物的多样性，但间作调控根际微生物抵御病害的效应和机制还不清楚。间作系统中涉及作物、寄主和非寄主病原菌等种间因子的互作，这些互作能否调控根际有益微生物帮助作物防御病害还不清楚。本项目拟在前期研究发现玉米和辣椒间作能通过种间互作诱导玉米激素信号途径关键基因表达和防御物质积累来减轻病害的基础上，深入研究间作系统中辣椒及病原菌（辣椒疫霉菌和玉米小斑病菌）与玉米的种间互作调控玉米根系分泌物来募集有益微生物抵御病害的效应和机制。本研究有利于从群体水平阐明多样性间作系统中作物—病原菌—根际微生物互作的调节机制，为利用作物多样性控病原理构建现代农业生态控病技术提供理论支撑；还可以了解作物通过根际代谢调控有益微生物形成的机制，为作物品种的遗传改良提供理论支撑。

植物在受到病原菌、害虫及其他生物或非生物因子胁迫后可以通过根系分泌物募集有益微生物帮助自己抵御胁迫。众多研究发现作物间作能增加土壤微生物的多样性，但间作调控根际微生物抵御病害的效应和机制还不清楚。间作系统中涉及作物、寄主和非寄主病原菌等种间因子的互作，这些互作能否调控根际有益微生物帮助作物防御病害还不清楚。. 本项目的研究表明，间作体系中玉米和辣椒受自身病原菌和非寄主病原菌攻击时，会引起根际土壤细菌群落结构和功能的改变，产生“利他行为”，使整个作物系统抗病能力增强。深入研究表明，单作系统中玉米受到小斑病菌（Bipolaris maydis）侵染后可以通过调控JA途径改变根系分泌物来募集假单胞菌（Pseudomonas）而诱发玉米自身对小斑病菌的抗性。间作系统中玉米和辣椒分别受到来自自生和邻居的寄主和非寄主病原菌攻击后均会通过改变根系代谢来调控根际微生物，产生“利他效应”（诱发自身抗性或拮抗根腐病菌）。其中，玉米受小斑病菌侵染后会通过调控JA途径改变根系分泌物来改变邻居辣椒根际微生物，显著增强玉米抵抗小斑病的能力并抑制辣椒疫病的危害；辣椒被自身病原菌（P. capsici）侵染会导致自身SA途径的改变而调控根系分泌物，导致玉米根际假单胞菌属显著上调，诱导玉米对小斑病菌的抗性；辣椒受到来自玉米的病原菌（B. maydis）诱导后会使辣椒和玉米的根际微生物均发生改变，且都能抑制辣椒疫病的危害。因此，作物多样性系统中，种间的相互作用有利于作物募集根际微生物来帮助彼此抵御病害的侵染，实现系统的平衡。. 本研究从群体水平阐明多样性间作系统中作物—病原菌—根际微生物互作的调节机制，为利用作物多样性控病原理构建现代农业生态控病技术提供理论支撑；还为了解作物通过根际代谢调控有益微生物形成的机制，为作物品种的遗传改良提供理论支撑。