叶部病原菌侵染对三七-土壤反馈效应的影响及机制研究

三七是我国独具特色的大宗药用植物之一，但连作障碍严重制约三七的健康生产。课题组前期研究表明，根系分泌物介导的植物-土壤负反馈导致病原菌的异常积累是三七连作障碍的重要成因。但当三七叶片被病原菌侵染后，三七根际土壤中病原菌的丰度会被抑制，而有益菌群的丰度上调。这表明三七在受病原菌侵染时可能通过根系募集有益微生物来抵御病害，也表明三七和土壤在特定的条件下可能存在正反馈调节，但其机制尚不清楚。因此，本项目拟在前期研究的基础上深入研究（1）叶部被活体和死体营养型病原菌侵染对三七—土壤反馈调节的影响；（2）叶部病原菌侵染对三七生长代谢和根系分泌物质的影响及其与反馈调节的关系；（3）叶部病原菌侵染诱导根系分泌物变化调控根际微生物结构和功能的机制。这些研究将深入解析生物胁迫对三七连作障碍的影响机制，为通过定向调控根际微生物菌群缓解三七连作障碍技术的研发找到新的突破口。

Sanqi (Panax notoginseng) is one of the most important medicinal herbs in China, but the growth is often hampered by the negative plant-soil feedback (NPSF). Our previous research demonstrated that the build-up of soil-borne pathogens mediated by root exudates is the main driven factor of NPSF. However, the relative abundance of soil-borne pathogens was suppressed and the beneficial microbes was enriched when the leaves were infected by pathogens. This inferred that sanqi root could recruit beneficial microbes to suppress root rot disease when it was infected by leaf pathogen. It also indicated that there may exist a positive feedback between sanqi and soil under biotic stress, but the mechanism is still unclear. The aim of this study is to (1) study the effect of leaf infection by biotrophic or necrotrophic pathogens on the direction and strength of sanqi-soil feedback; (2) clarify the changes of metabolism and root exudates of sanqi induced by the infection of leaf pathogen and its relationship with feedback; (3) decipher the mechanism of root exudates in modifying the composition and function of rhizosphere microbiome. These studies will help us to further understand the mechanism of biotic stress on sanqi replant failure and develop the novel technique to manipulate the rhizosphere microbiome to alleviate sanqi replant failure.