Department of Agriculture and Ecology, University of Copenhagen, 1871 Frederiksberg, Denmark.
Mol Plant Pathol. 2012 Dec;13(9):1110-9. doi: 10.1111/j.1364-3703.2012.00820.x. Epub 2012 Aug 1.
A large number of effector candidates have been identified recently in powdery mildew fungi. However, their roles and how they perform their functions remain unresolved. In this study, we made use of host-induced gene silencing and confirmed that the secreted barley powdery mildew effector candidate, CSEP0055, contributes to the aggressiveness of the fungus. This result suggests that CSEP0055 is involved in the suppression of plant defence. A yeast two-hybrid screen indicated that CSEP0055 interacts with members of the barley pathogenesis-related protein families, PR1 and PR17. Interaction with PR17c was confirmed by bimolecular fluorescence complementation analyses. Down-regulation and over-expression of PR17c in epidermal cells of barley confirmed that this protein is important for penetration resistance against the powdery mildew fungus. In line with this, PR17c was found to be apoplastic, localizing to the papillae formed in response to this fungus. The CSEP0055 transcript did not start to accumulate until 24 h after inoculation. This suggests that this gene is expressed too late to influence primary penetration events, but rather sustains the fungus at sites of secondary penetration, where PR17c appears to be able to accumulate.
最近在白粉菌中鉴定出了大量的效应子候选物。然而，它们的作用以及它们如何发挥作用仍未得到解决。在这项研究中，我们利用寄主诱导基因沉默技术证实了分泌的大麦白粉菌效应子候选物 CSEP0055 有助于真菌的侵袭性。这一结果表明 CSEP0055 参与了植物防御的抑制。酵母双杂交筛选表明 CSEP0055 与大麦病程相关蛋白家族的成员 PR1 和 PR17 相互作用。通过双分子荧光互补分析证实了与 PR17c 的相互作用。在大麦表皮细胞中下调和过表达 PR17c 证实了该蛋白对抵御白粉菌的穿透抗性很重要。与此一致的是，发现 PR17c 是质外体的，定位于对该真菌产生的乳突中。CSEP0055 转录本在接种后 24 小时才开始积累。这表明该基因表达得太晚，无法影响初级穿透事件，而是在次级穿透部位维持真菌，而 PR17c 似乎能够在这些部位积累。
