A Small Secreted Virulence-Related Protein Is Essential for the Necrotrophic Interactions of Sclerotinia sclerotiorum with Its Host Plants.
A Small Secreted Virulence-Related Protein Is Essential for the Necrotrophic Interactions of Sclerotinia sclerotiorum with Its Host Plants.
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一种小的分泌毒力相关蛋白对于核盘菌与其宿主植物的坏死性营养相互作用至关重要
DOI：
10.1371/journal.ppat.1005435
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发表时间：
2016-02
期刊：
影响因子：
6.7
通讯作者：
Cheng J
中科院分区：
文献类型：
--
作者：
Lyu X;Shen C;Fu Y;Xie J;Jiang D;Li G;Cheng J
已发现小分子分泌蛋白在生物营养/半生物营养病原菌与植物的相互作用中起着关键作用。然而，对这些由广泛宿主范围的坏死性植物病原体产生的蛋白质在感染过程中所起的作用知之甚少。在这里，我们报道了一个富含半胱氨酸的小蛋白SsSSVP1被实验证实是一种分泌型蛋白，该蛋白是一种分泌型蛋白，从菌丝中分泌SsSSVP1之后，宿主细胞中的SsSSVP1被内化和细胞间移动。SsSSVP1∆SP可诱导植物细胞显著死亡，靶向沉默SsSSVP1可显著降低植物的致病力。通过酵母双杂交(Y2H)、免疫共沉淀(co-IP)和双分子荧光互补(BIFC)实验，我们证明了SsSSVP1∆SP与植物线粒体呼吸链细胞色素b-c1复合体的一个亚基QCR8相互作用。SsSSVP1∆SP上两个半胱氨酸残基(C38和C44)的双定点突变对其同源二聚体的形成、SsSSVP1QCR8与∆SP的相互作用和植物细胞死亡诱导都有显著影响，表明部分半胱氨酸残基在维持SsSSVP1的结构和功能中起着关键作用。共定位和生物免疫印迹分析表明，SsSSVP1∆SP可能在QCR8靶向线粒体之前将其劫持到细胞质，从而干扰其在植物细胞中的亚细胞定位。此外，病毒诱导的烟草QCR8基因沉默导致植株发育异常和细胞死亡，这表明SsSSVP1∆SP诱导的细胞死亡可能是由于SsSSVP1∆SP与QCR8相互作用，扰乱了QCR8的亚细胞定位，从而使其生物学功能丧失所致。这些结果表明，SsSSVP1是一个潜在的效应因子，可能通过调节植物的能量代谢来促进核盘菌的侵染。我们的发现表明，小分泌蛋白在寄主-非特异性坏死性真菌与植物之间的相互作用中具有新的作用，并强调了阐明这种相互作用的致病机制的重要性。
Small, secreted proteins have been found to play crucial roles in interactions between biotrophic/hemi-biotrophic pathogens and plants. However, little is known about the roles of these proteins produced by broad host-range necrotrophic phytopathogens during infection. Here, we report that a cysteine-rich, small protein SsSSVP1 in the necrotrophic phytopathogen Sclerotinia sclerotiorum was experimentally confirmed to be a secreted protein, and the secretion of SsSSVP1 from hyphae was followed by internalization and cell-to-cell movement independent of a pathogen in host cells. SsSSVP1∆SP could induce significant plant cell death and targeted silencing of SsSSVP1 resulted in a significant reduction in virulence. Through yeast two-hybrid (Y2H), coimmunoprecipitation (co-IP) and bimolecular fluorescence complementation (BiFC) assays, we demonstrated that SsSSVP1∆SP interacted with QCR8, a subunit of the cytochrome b-c1 complex of mitochondrial respiratory chain in plants. Double site-directed mutagenesis of two cysteine residues (C38 and C44) in SsSSVP1∆SP had significant effects on its homo-dimer formation, SsSSVP1∆SP-QCR8 interaction and plant cell death induction, indicating that partial cysteine residues surely play crucial roles in maintaining the structure and function of SsSSVP1. Co-localization and BiFC assays showed that SsSSVP1∆SP might hijack QCR8 to cytoplasm before QCR8 targeting into mitochondria, thereby disturbing its subcellular localization in plant cells. Furthermore, virus induced gene silencing (VIGS) of QCR8 in tobacco caused plant abnormal development and cell death, indicating the cell death induced by SsSSVP1∆SP might be caused by the SsSSVP1∆SP-QCR8 interaction, which had disturbed the QCR8 subcellular localization and hence disabled its biological functions. These results suggest that SsSSVP1 is a potential effector which may manipulate plant energy metabolism to facilitate the infection of S. sclerotiorum. Our findings indicate novel roles of small secreted proteins in the interactions between host-non-specific necrotrophic fungi and plants, and highlight the significance to illuminate the pathogenic mechanisms of this type of interaction.