PLD介导的ROS调控Trichothecium roseum致病和产毒的分子机制

Trichothecium roseum是导致果蔬采后腐烂的重要病原真菌，还可代谢产生单端孢霉烯族毒素。有报道表明，真菌磷脂酶D(PLD)除了影响菌体生长发育，还参与对寄主的致病和产毒，但作用机理不明。我们推测，T.roseum的PLD首先作用于寄主质膜磷脂结构中的磷酸二酯键，产生磷脂酸(PA)，PA与质膜上NADPH氧化酶(NOX)互作，磷酸化产生ROS。ROS攻击寄主膜系统导致膜完整性受损脂质过氧化、加速寄主致病。此外，H2O2还可与毒素代谢关键转录因子Tri6互作从而调控毒素合成。据此，本研究通过构建T.roseum的Trpld缺失突变体，观察突变体和野生型在菌体生长发育和致病性的差异，通过转录组学分析PLD与致病和毒素合成相关代谢途径，明确PA与NOX及H2O2与Tri6的互作机制。从细胞生物学、生物化学和分子生物学水平揭示PLD介导的ROS调控T.roseum致病和产毒的分子机制

Trichothecium roseum is a typical necuotrophic fungal pathogen, infecting various postharvest fruits and vegetables, which can also lead to trichothecenes contamination. There is reported that phospholipase D (PLD) not only affects the growth and development of pathogen, but also influences pathogenicity to host and mycotoxin production. However, the detail action mechanism has not been documented. We hypothesis that PLD hydrolyzes the phosphodiester bond of the phospholipid backbone on the host’s plasma membrane to generate phosphatidic acid (PA) during T. roseum infecting host, and PA and NADPH oxidase (NOX) integrate and interact, then NOX is phosphorylated and activated to produce superoxide anion, then the superoxide anion is generated to H2O2 by superoxide dismutase (SOD). On the one hand, ROS acts as a pathogenic factor to attack plasma membrane of host, and leads to cell membrane damage, lipid peroxidation, which accelerates host cell death. On the other hand, H2O2 interacts with Tri6 of the transcription factor of trichothecene metabolic pathway, and regulates trichothecene metabolism. In this project, we are using T. roseum to construct mutant of Trpld, and to observe the difference of growth phenotype, hyphal micromorphology, cell ultrastructure, and pathogenicity between the knock-out mutants of Trpld and wild type of T. roseum, and to anaylze and verify the relationship between PLD and the related metabolic pathway of pathogenicity, trichothecene production based on the transcriptomics results, and to elaborate the mechanism of the interaction between PA and NOX, and the interaction between H2O2 and Tri6. On the basis of the above results, the molecular mechanism of PLD-mediated ROS regulating the pathogenicity and trichothecenes production is elucidated on the level of cell biology, biochemistry, and molecular biology.