RAC/ROP signaling in the interaction of Arabidopsis and barley with powdery mildew fungi

小分子单体RAC/ROP GTP酶是细胞极性和植物防御反应的分子开关。为了鉴定大麦RAC/ROP相互作用蛋白(RAC/ROP-IPs)，我们进行了大麦HvRAC1相互作用蛋白的非靶向酵母双杂交筛选。这揭示了28个潜在的相互作用伙伴，包括参与调节RAC/ROP活性、信号转导、内吞和胞吐的有前途的候选对象。一个HvRAC1结合蛋白和一个新的细胞骨架相关的RAC/ROP GTP酶激活蛋白被发现影响大麦和白粉菌的相互作用结果。这些RAC/ROP-IP目前正在详细分析它们在大麦和拟南芥与白粉菌相互作用中的功能。此外，我们还分析了与大麦RAC/ROP-IPs对应的54个拟南芥突变体的白粉病侵染表型。这揭示了7个突变体对真菌的致病超级敏感或部分抗性。我们将分析相应的大麦和拟南芥RAC/ROP-IP在植物蛋白质-蛋白质相互作用中的作用，以及它们在植物-真菌相互作用过程中在细胞重编程中的作用。

Small monomeric RAC/ROP GTPases are molecular switches in cell polarity and plant defence responses. To identify barley RAC/ROP-interacting proteins (RAC/ROP-IPs), we have carried out a non-targeted yeast two hybrid screening for barley HvRAC1-interacting proteins. This revealed 28 potential interaction partners including promising candidates involved in regulation of RAC/ROP activity, signalling, endocytosis and exocytosis. A HvRAC1-binding kinase and a novel cytoskeleton associated RAC/ROP GTPase activating protein have been found to influence the interaction outcome of barley and Blumeria graminis. These RAC/ROP-IPs are now subject of detailed analysis of their function in interaction of barley and Arabidopsis with powdery mildew fungi. Additionally, we analysed 54 Arabidopsis mutant genotypes corresponding to barley RAC/ROP-IPs for aberrant powdery mildew infection phenotypes. This revealed 7 mutants super-susceptible or partially resistant to fungal pathogenesis. We are going to analyse corresponding barley and Arabidopsis RAC/ROP-IPs in respect to in planta protein-protein interaction and to their role in cellular reprogramming during the plant-fungus interaction.