Characterization of Blumeria graminis peptides as potential effectors targeting barley RAC/ROP proteins

小单体RAC/ROP GTP酶是细胞极性和植物防御反应的分子开关。在大麦中，RACB和相关RAC/ROP在对生养型子囊菌病原体大麦白粉病菌（Blumeria graminis f.sp. hordei，Bgh）的易感性中起作用。为了鉴定与RACB相互作用的蛋白质，我们利用酵母双杂交技术对感染的大麦cDNA文库进行了筛选。这鉴定了六个编码同一类小肽的真菌克隆。蛋白质-蛋白质相互作用在独立的测定中得到证实，并且真菌RACB相互作用肽的GFP融合蛋白标记了细胞质和细胞皮质中的小结构，并在病原体进入的位点处积累。过表达或宿主诱导的基因沉默的两个BGH-肽，增强或降低的易感性真菌进入，分别。通过使用细胞生物学和遗传学工具，我们现在想提供证据表明，肽代表真菌毒力效应子，其靶向大麦RAC/ROP以获得效应子触发的易感性。

Small monomeric RAC/ROP GTPases are molecular switches in cell polarity and plant defence responses. In barley RACB and related RAC/ROPs function in susceptibility to the biotrophic ascomycete pathogen Blumeria graminis f.sp. hordei (Bgh). To identify RACBinteracting proteins, we have carried out yeast two hybrid screenings of a cDNA library from infected barley. This identified six fungal clones coding for to the same class of small peptides. Protein-protein interaction was confirmed in independent assays, and a GFP-fusion protein of a fungal RACB-interacting peptide labelled small structures in the cytoplasm and cell cortex and accumulated at the site of pathogen entry. Over-expression or host-induced gene silencing of two Bgh-peptides, enhanced or reduced susceptibility to fungal entry, respectively. By the use of cell-biological and genetic tools, we would like now to provide evidence that the peptides represent fungal virulence effectors that target barley RAC/ROPs for effector-triggered susceptibility.