An Effector-Targeted Protease Contributes to Defense against Phytophthora infestans and Is under Diversifying Selection in Natural Hosts
An Effector-Targeted Protease Contributes to Defense against Phytophthora infestans and Is under Diversifying Selection in Natural Hosts
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DOI：
10.1104/pp.110.158030
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发表时间：
2010-12-01
期刊：
影响因子：
7.4
通讯作者：
van der Hoorn, Renier A. L.
中科院分区：
文献类型：
--
作者：
Kaschani, Farnusch;Shabab, Mohammed;van der Hoorn, Renier A. L.
由于叶质外体是许多植物病原菌的主要栖息地，质外体蛋白是植物病原菌分泌的质外体效应物的有效、古老的靶标。然而，到目前为止，只有少数质外体效应靶被识别和表征。在此，我们发现类木瓜蛋白酶C14是马铃薯晚疫病病原菌马铃薯晚疫病菌EPIC1和EPIC2B的一个新的共同靶标。EPIC1和EPIC2B是马铃薯晚疫病菌分泌的两种质外体类胱抑素蛋白。C14是番茄(Solanum Lycopsicum)和马铃薯的一种分泌型蛋白酶，具有羧基末端的颗粒蛋白结构域。EPIC-C14的相互作用发生在较宽的pH范围内，并且比先前描述的EPIC与番茄防御蛋白PIP1和RCR3的相互作用更强。与番茄叶霉病菌的AVR2效应子相比，EPICS的选择性也不同，后者针对PIP1和RCR3，仅在质外体pH下。重要的是，C14的沉默增加了对致病疫霉的敏感性，表明这种蛋白酶在病原体防御中发挥作用。虽然C14在番茄中处于保守选择状态，但在作为致病疫霉自然宿主的野生马铃薯物种(Solanum demissm、Solanum verrucosum和Solanum stoliniferum)中，C14处于多样化选择之下。这些数据揭示了质外体中一个新的效应靶点，它有助于免疫，并处于多样化选择之下，但仅在病原体的自然宿主中。
Since the leaf apoplast is a primary habitat for many plant pathogens, apoplastic proteins are potent, ancient targets for apoplastic effectors secreted by plant pathogens. So far, however, only a few apoplastic effector targets have been identified and characterized. Here, we discovered that the papain-like cysteine protease C14 is a new common target of EPIC1 and EPIC2B, two apoplastic, cystatin-like proteins secreted by the potato (Solanum tuberosum) late blight pathogen Phytophthora infestans. C14 is a secreted protease of tomato (Solanum lycopersicum) and potato typified by a carboxyl-terminal granulin domain. The EPIC-C14 interaction occurs at a wide pH range and is stronger than the previously described interactions of EPICs with tomato defense proteases PIP1 and RCR3. The selectivity of the EPICs is also different when compared with the AVR2 effector of the fungal tomato pathogen Cladosporium fulvum, which targets PIP1 and RCR3, and only at apoplastic pH. Importantly, silencing of C14 increased susceptibility to P. infestans, demonstrating that this protease plays a role in pathogen defense. Although C14 is under conservative selection in tomato, it is under diversifying selection in wild potato species (Solanum demissum, Solanum verrucosum, and Solanum stoliniferum) that are the natural hosts of P. infestans. These data reveal a novel effector target in the apoplast that contributes to immunity and is under diversifying selection, but only in the natural host of the pathogen.