Plant‐parasitic nematodes secrete effectors that manipulate plant cell morphology and physiology to achieve host invasion and establish permanent feeding sites. Effectors from the highly expanded SPRYSEC (SPRY domain with a signal peptide for secretion) family in potato cyst nematodes have been implicated in activation and suppression of plant immunity, but the mechanisms underlying these activities remain largely unexplored. To study the host mechanisms used by SPRYSEC effectors, we identified plant targets of GpRbp‐1 from the potato cyst nematode Globodera pallida. Here, we show that GpRbp‐1 interacts in yeast and in planta with a functional potato homologue of the Homology to E6‐AP C‐Terminus (HECT)‐type ubiquitin E3 ligase UPL3, which is located in the nucleus. Potato lines lacking StUPL3 are not available, but the Arabidopsis mutant upl3‐5 displaying a reduced UPL3 expression showed a consistently small but not significant decrease in susceptibility to cyst nematodes. We observed a major impact on the root transcriptome by the lower levels of AtUPL3 in the upl3‐5 mutant, but surprisingly only in association with infections by cyst nematodes. To our knowledge, this is the first example that a HECT‐type ubiquitin E3 ligase is targeted by a pathogen effector and that a member of this class of proteins specifically regulates gene expression under biotic stress conditions. Together, our data suggest that GpRbp‐1 targets a specific component of the plant ubiquitination machinery to manipulate the stress response in host cells.

中文翻译：

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Globodera pallida的效应子GpRbp-1靶向核HECT E3泛素连接酶，以调节宿主中的基因表达。

植物寄生线虫分泌效应物，可操纵植物细胞的形态和生理学来实现宿主入侵并建立永久性的取食点。马铃薯囊肿线虫中高度扩展的SPRYSEC（带有分泌信号肽的SPRY结构域）家族的效应子与植物免疫力的激活和抑制有关，但这些活性的机制尚待进一步研究。为了研究SPRYSEC效应子使用的宿主机制，我们从马铃薯孢囊线虫Globodera pallida鉴定了GpRbp-1的植物靶标。在这里，我们证明了GpRbp-1在酵母和植物中相互作用与位于核内的E6-AP C末端（HECT）型泛素E3连接酶UPL3同源的功能马铃薯同源物。缺乏StUPL3的马铃薯品系不可用，但是显示UPL3表达降低的拟南芥突变体upl3-5显示出对囊肿线虫的敏感性持续不断的降低，但没有显着降低。我们在观察到下级AtUPL3根上转录产生重大影响upl3-5突变，但令人惊讶的是仅与囊肿线虫感染有关。据我们所知，这是第一个实例，表明病原体效应子靶向HECT型泛素E3连接酶，并且这类蛋白质的成员在生物胁迫条件下特异性调节基因表达。总之，我们的数据表明GpRbp-1靶向植物泛素化机制的特定组成部分，以操纵宿主细胞中的应激反应。