Detection of phytopathogenic Xanthomonads via a novel perception mechanism in Arabidopsis thaliana

黄单胞菌属的许多细菌是农作物的严重病原菌。在我们以前的工作中，我们检测到，作为其防御系统的一部分，模式植物拟南芥具有通过模式识别受体ReMAX/RLP 1检测黄单胞菌属的方法，该受体检测来自黄单胞菌属细菌的特定但尚未鉴定的蛋白质。在我们正在进行的纯化和鉴定这种蛋白质的尝试中，我们检测到了第二个因子，该因子以ReMAX/RLP 1独立的方式被拟南芥感知。这第二个因子的纯化被证明是比较容易的，并允许其鉴定为由黄单胞菌属细菌分泌的枯草杆菌酶。到目前为止，我们的结果表明，它不是枯草杆菌酶分子本身，这是感觉。相反，我们的证据表明，细菌枯草杆菌酶的蛋白水解活性将植物细胞输出的蛋白质加工成较小的多肽，该多肽通过特定的表面受体在植物细胞中触发典型的防御反应。为了表征这种新的分子病原体感知机制，本项目的主要目的是鉴定这种植物因子，称为SAMP的枯草杆菌酶激活的分子模式，及其同源植物受体。

Many bacterial species of the genus Xanthomonas are serious pathogens for crop plants. In our previous work we detected that, as part of their defense system, the model plant Arabidopsis has means to detect Xanthomonas via the pattern recognition receptor ReMAX/RLP1 that detects a specific, but yet unidentified, protein from Xanthomonas bacteria. In our ongoing attempts to purify and identify this protein, we detected a second factor that is perceived by Arabidopsis in a ReMAX/RLP1 independent way. Purification of this second factor proved easier and allowed its identification as a subtilase enzyme secreted by the Xanthomonas bacteria. Our results, so far, show that it is not the subtilase molecule itself, which is sensed. Rather, our evidence shows that the proteolytic activity of the bacterial subtilase processes a protein exported by the plant cells to a smaller polypeptide that triggers typical defense responses in plant cells via a specific surface receptor. In order to characterize this novel molecular pathogen perception mechanism, the primary aims of this project are the identification of this plant factor, termed SAMP for subtilase activated molecular pattern, and its cognate plant receptor.