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

MLO蛋白是一类植物特异的、七螺旋的、定位于质膜的整膜蛋白家族。大麦MLO是蛋白质家族的“创建者”，在病原菌防御和细胞死亡中起着调节器的作用，并被认为在细胞外围调节依赖SNARE蛋白和囊泡相关的防御途径。我们测试了拟南芥MLO基因中的T-DNA插入突变体在受到一系列植物病原体攻击时感染表型的变化。我们发现AtMlo2 u突变体与前面描述的pmr2突变体是等位的，并且AtMlo2突变体等位基因与大麦MLO突变体的广谱白粉病抗性表型相同。这一发现表明MLO蛋白在单子叶和双子叶植物中具有保守的作用，并表明白粉菌操纵MLO途径的能力已经保留了至少1.5亿年。我们将利用这一新发现，通过S的各种方法，包括MLO信号需求分析、Atmlo2抑制子突变和比较转录谱，来揭示拟南芥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.