The powdery mildew resistance protein RPW8.2 is carried on VAMP721/722 vesicles to the extrahaustorial membrane of haustorial complexes
The powdery mildew resistance protein RPW8.2 is carried on VAMP721/722 vesicles to the extrahaustorial membrane of haustorial complexes
复制标题
DOI：
10.1111/tpj.12591
复制
发表时间：
2014-09-01
期刊：
影响因子：
7.2
通讯作者：
Schulze-Lefert, Paul
中科院分区：
文献类型：
--
作者：
Kim, Hyeran;O'Connell, Richard;Schulze-Lefert, Paul
植物采用多种细胞自主防御机制来阻止微生物入侵者的致病。以前，我们确定了一个胞吐防御机制在拟南芥对致病性白粉病真菌。这种侵入前防御机制依赖于由质膜定位的PEN 1突触融合蛋白、接头蛋白SNAP 33和与序列密切相关的囊泡驻留VAMP 721或VAMP 722蛋白组成的三元蛋白复合物的形成。拟南芥抗白粉病8.2蛋白（RPW8.2）在真菌进入宿主细胞后赋予对白粉病的抗病性，并且特异性地靶向于吸器外膜（EHM），该吸器外膜是真菌的吸器复合体。然而，参与运输RPW8.2到EHM的分泌机制尚不清楚。在这里，我们报告，RPW8.2是暂时定位于VAMP 721/722囊泡，后来纳入成熟吸器的EHM。在不存在VAMP 721的情况下，RPW8.2对白粉病Golovinomyces orontii的抗性活性大大降低，但在不存在VAMP 722的情况下仅略微降低。与该结果一致，在不存在VAMP 721的情况下，RPW8.2向EHM的运输被延迟。这些发现暗示VAMP 721/722囊泡作为将RPW8.2携带到植物-真菌界面的分泌机制的关键组分。光漂白后的定量荧光恢复表明，囊泡介导的贩运RPW8.2-黄色荧光蛋白（YFP）的EHM发生短暂的早期吸器的发展和横向扩散的RPW8.2-YFP内的EHM超过囊泡介导的补充RPW8.2-YFP在成熟吸器。我们的研究结果表明VAMP 721/722参与了一个分叉的运输途径，用于细胞周边的侵入前防御和EHM的侵入后防御。
Plants employ multiple cell-autonomous defense mechanisms to impede pathogenesis of microbial intruders. Previously we identified an exocytosis defense mechanism in Arabidopsis against pathogenic powdery mildew fungi. This pre-invasive defense mechanism depends on the formation of ternary protein complexes consisting of the plasma membrane-localized PEN1 syntaxin, the adaptor protein SNAP33 and closely sequence-related vesicle-resident VAMP721 or VAMP722 proteins. The Arabidopsis thaliana resistance to powdery mildew 8.2 protein (RPW8.2) confers disease resistance against powdery mildews upon fungal entry into host cells and is specifically targeted to the extrahaustorial membrane (EHM), which envelops the haustorial complex of the fungus. However, the secretory machinery involved in trafficking RPW8.2 to the EHM is unknown. Here we report that RPW8.2 is transiently located on VAMP721/722 vesicles, and later incorporated into the EHM of mature haustoria. Resistance activity of RPW8.2 against the powdery mildew Golovinomyces orontii is greatly diminished in the absence of VAMP721 but only slightly so in the absence of VAMP722. Consistent with this result, trafficking of RPW8.2 to the EHM is delayed in the absence of VAMP721. These findings implicate VAMP721/722 vesicles as key components of the secretory machinery for carrying RPW8.2 to the plant-fungal interface. Quantitative fluorescence recovery after photobleaching suggests that vesicle-mediated trafficking of RPW8.2-yellow fluorescent protein (YFP) to the EHM occurs transiently during early haustorial development and that lateral diffusion of RPW8.2-YFP within the EHM exceeds vesicle-mediated replenishment of RPW8.2-YFP in mature haustoria. Our findings imply the engagement of VAMP721/722 in a bifurcated trafficking pathway for pre-invasive defense at the cell periphery and post-invasive defense at the EHM.