内生真菌稻镰状瓶霉与水稻互作机制的研究

Currently，much researches about the dark septate endophyte (DSEs) are focused on the diversity, ecological distribution and biological function. However, the symbiotic interactions of DSEs-plants are known less. Harpophora oryzae , isolated from the wild rice roots, was identified as a DSE. One pathogenic mutant SOD1T-DNAfrom libraries could not only infect roots and lead the plants to die, but also infect the leaves by appresorium, spread by nervation and cause leave necrosis. What triggers the interaction from mutualistic to pathogenic? In this study, we’ll analize the biological function of the mutated gene from different levels of biochemical metabolism, cell structure, and pathogenicity. Through the gene expression profile analysis, we’ll find the gene expression difference and the key metabolic and signaling pathways regulating symbiotic balance. Moreover, more genes which invovle in regulating the symbiotic interaction and improving fungal pathogenicity will be explored by co-immunoprecipitation. This work will reveal the interaction mechanism of H. oryzae and rice.

目前，对暗色有隔内生真菌（DSEs）的多样性、生态分布、生物学功能研究较多，而对DSEs与植物的共生互作机制缺乏深入研究。稻镰状瓶霉（Harpophora oryzae）是从野生稻根部分离的一株DSE。从突变体库中筛选到一株致病型突变体菌株SOD1T-DNA，不仅能侵染根部致病，导致植株死亡，还能在叶部产生附着胞结构，侵染表皮细胞，通过叶脉进行扩散传播，产生黑色病斑，导致叶片组织坏死。是什么原因导致H. oryzae与水稻的互作关系由共生转变为致病？本项目拟从生化代谢、细胞结构、生长发育及致病性等水平全面分析突变基因的生物学功能。通过表达谱分析、免疫共沉淀技术，明确该基因的缺失导致哪些基因的差异表达，寻找调控共生平衡的关键代谢与信号途径，并挖掘参与调控共生平衡的其他互作基因，以及这些基因在维护共生平衡，提高菌株致病性中的生物学功能，全面详尽地阐明H. oryzae与水稻共生互作的分子机制。

目前，对暗色有隔内生真菌（DSEs）与植物的共生互作机制缺乏深入研究。通过该项目的研究，明确了稻镰状瓶霉致病突变体菌株SOD1T-DNA基因突变位点及突变基因。通过基因敲除获得该基因缺失突变体ΔSOD1，不仅能侵染水稻根部致病，导致植株死亡，还能在叶部产生附着胞结构，侵染表皮细胞，产生黑色病斑，导致叶片组织坏死。通过代谢组学分析发现，野生型与SOD1T-DNA菌株侵染水稻不同时期的差异代谢物主要包括糖类、氨基酸和脂类。结合转录组学发现，差异表达基因也是集中富集在蛋白水解与生物合成过程。SOD1T-DNA菌株致病的原因主要与糖代谢途径、氨基酸代谢途径相关。SOD1T-DNA菌株中g6649（木质素酶）显著上调表达，意味着SOD1T-DNA降解寄主木质素的能力和侵染力提高，从而打破共生平衡关系。本项目将有益于进一步认识DSEs 与植物的共生互作机制，对揭秘内生真菌与植物的共生关系具有重要科学指导意义。