Mechanisms of fungal pathogens' adaptation to plant defenses

了解病原体如何感染植物以及植物如何对这种攻击做出反应，对于制定基于知识的植物病害管理策略至关重要。然而，真菌病原体为对抗植物防御而采取的措施也是方程的重要组成部分。我的研究项目目前的重点是了解病原体如何对植物防御策略做出反应，以及它们如何为自己的利益操纵植物的新陈代谢。我们利用马铃薯黄萎病和马铃薯晚疫病菌两种病原系统，通过评估它们对植物防御机制的影响，验证了这些反防御的机制。利用蛋白质组学和消减杂交(SH)/cDNA-AFLP相结合的方法，我们鉴定了几个在这两个病理系统中可能参与的差异表达基因和蛋白。在大丽弧菌中，我们鉴定了只有在高表达而不是弱攻击的分离物中差异表达的基因和蛋白质，并且只有在用马铃薯根提取物诱导后才有差异表达。可能参与反防御的基因和蛋白质正在进行研究。我这项研究计划的目的是调查潜在的致病基因和蛋白是否以及如何影响植物防御并改变寄主-病原体相互作用的结果，以及病原体如何在基因和代谢物水平上协调这种植物防御变化。在气候变化等涉及环境的全球问题下，病原体对宿主的适应似乎将更加重要。能够预测病原菌的适应性反应将为针对病原菌的特定功能来处理植物病害开辟新的视野。

Understanding how pathogens infect plants and how plants respond to such attacks is critical for the development of knowledge-based plant disease management strategies. However, the measures taken by fungal pathogens to counteract plant defenses also are important parts of the equation. My research program currently focuses on understanding how pathogens respond to plant defense strategies and how they manipulate plants' metabolism to their advantage. We validate the mechanisms underlying these counterdefenses by assessing their impact on plant defense mechanisms using two pathosystems, potato-Verticillium dahliae and potato- Phytophthora infestans. Using proteomics and a subtractive hybridization (SH)/cDNA-AFLP combinational approach, we identified several differentially expressed genes and proteins potentially involved in these two pathosystems. In V. dahliae, we identified genes and proteins differentially expressed only in a highly, not a weakly, aggressive isolate and only after induction with potato root extracts. Genes and proteins potentially involved in counterdefense are being investigated. The objectives of my research program for the term of this Discovery grant proposal are to investigate whether and how potential pathogenicity genes and proteins that express only in highly aggressive isolates of V. dahliae (i.e., SrrA, ICH) impact plant defenses and alter the outcome of host-pathogen interactions, and how the pathogen coordinates such plant defense alterations at gene and metabolite levels. Adaptation of pathogens to their hosts will seemingly be more significant under global issues involving the environment, such as climate change. Being able to anticipate adaptive reactions of pathogens will open new horizons in dealing with plant diseases by targeting specific functions of the pathogen.