被子植物TIR-NBS-LRR类抗病基因演化丢失的分子机制

植物抗病基因（R gene）与病原的协同演化是植物生存和繁衍的基础保障。重要R基因家族——TIR-NBS-LRR（TNL）基因在被子植物多个类群中的独立丢失，长期以来一直是R基因演化研究的谜题。申请人在多年来对R基因演化研究和预研论证的基础上，提出TNL基因丢失是由NRG1基因及其它抗病信号传导基因丢失所共同导致的科学假说。针对于此，本项目拟通过演化生物学分析和分子生物学验证，深入发掘除NRG1以外与TNL基因同时丢失的其它抗病信号传导基因；系统研究这些抗病信号传导基因与NRG1分别介导了哪些TNL演化谱系的抗病信号传导；探索这些抗病信号传导基因与NRG1在不同物种中丢失的先后顺序和分子机制，综合分析并建立TNL基因丢失的演化模型。研究内容不仅有望从机制上解答TNL这一重要R基因类型的丢失之谜，还将架起R基因与其信号传导机制协同演化的桥梁，为深入理解植物免疫系统的演化模式提供新的见解。

The co-evolution of plant disease resistance genes (R genes) and pathogens is vital for the survival and development of plants. TIR-NBS-LRR (TNL) is an important type of R gene against various pathogens. The independent loss of TNL genes from several angiosperm lineages has been a mystery of R gene evolution for a long time. Basing on our long-term study on plant R gene’s evolution and several recently accomplished preliminary surveys, we propose that loss of NRG1 and other signal transduction genes may contribute to the erase of TNL genes from several angiosperm lineages. The present project is designed to verify our hypothesis. Firstly, ancestral TNL lineages will be differentiated basing on systematic phylogenetic analysis and their dependence on NRG1 for immune reaction will be experimentally tested. Then, defense signal transduction genes other than NRG1 that co-absent with TNL genes among angiosperm genomes will be screened by comparative genomics analysis. Furthermore, the dependence of NRG1-independent TNL genes on the newly found signal transduction genes will be tested. Finally, the underling mechanisms of loss of NRG1 and other signal transduction genes will be explored. The results from this project are aimed to resolve the mystery of TNL loss. It will be helpful for understanding how signal transduction mechanisms and the preservation/loss patterns of disease resistance genes are co-evolved, and provide new insights into the adaptive evolution of plant immune systems.