Functional analysis of the Arabidopsis thaliana Mlo (AtMlo) gene family

MLO蛋白是一类植物特异性、七螺旋、质膜定位的完整膜蛋白。大麦MLO是该蛋白家族的“奠基人”，可作为病原体防御和细胞死亡的调节剂，并被认为可调节细胞外周的SNARE蛋白依赖和囊泡相关防御途径。我们测试了拟南芥Mlo基因中的T-DNA插入突变体在一系列植物病原体的攻击下改变感染表型。我们发现，AtMlo2突变体与先前描述的pmr2突变体是等位基因，并且AtMlo2突变体的等位基因表型与大麦mlo突变体的广谱白粉病抗性表型相似。这一发现表明MLO蛋白在单子叶和双子叶植物中的保守作用，并表明白粉病真菌操纵MLO途径的能力至少保留了1.5亿年。我们将利用这一新发现，通过各种方法，包括分析MLO信号需求、Atmlo2抑制因子突变和比较转录谱，揭示拟南芥中MLO功能的分子基础。

MLO proteins constitute a family of plant-specific, heptahelical, plasma membrane-localized integral membrane proteins. Barley MLO, the "founder" of the protein family, serves a role as modulator of pathogen defence and cell death and is assumed to regulate a SNARE protein-dependent and vesicle-associated defence pathway at the cell periphery. We tested T-DNA insertion mutants in Arabidopsis Mlo genes for altered infection phenotypes upon challenge with a range of phytopathogens. We found that the AtMlo2 mu tant is allelic to the previously described pmr2 mutant and that AtMlo2 mutant alleles phenocopy the broad-spectrum powdery-mildew resistant phenotype of barley mlo mutants. This finding suggests a conserved role for MLO proteins in monocot and dicot plants and indicates that the ability of powdery mildew fungi to manipulate the MLO pathway has been retained for at least 150 million years. We will exploit this novel discovery to unravel the molecular basis of MLO function in Arabidopsis by various approache s including analysis of mlo signaling requirements, Atmlo2 suppressor mutagenesis, and comparative transcript profiling.