A Secreted Fungal Effector of Glomus intraradices Promotes Symbiotic Biotrophy
A Secreted Fungal Effector of Glomus intraradices Promotes Symbiotic Biotrophy
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DOI：
10.1016/j.cub.2011.06.044
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发表时间：
2011-07-26
期刊：
影响因子：
9.2
通讯作者：
Requena, Natalia
中科院分区：
文献类型：
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作者：
Kloppholz, Silke;Kuhn, Hannah;Requena, Natalia
与植物相互作用的生养真菌与其宿主建立长期关系以完成其生活史。与坏死营养型相反，它们需要与植物的防御机制相抗衡，以在宿主体内发育并以活细胞为食[1]。普遍认为微生物病原体产生并递送无数效应蛋白以劫持其宿主的细胞程序[1 - 5]。丛枝菌根（AM）真菌是植物根部最广泛的生物营养体[6]。我们研究了AM真菌是否使用效应蛋白来短路植物防御程序。在这里，我们表明根内球囊霉分泌一种蛋白质SP7，该蛋白质与植物细胞核中病程相关的转录因子ERF 19相互作用。ERF19是高度诱导的真菌病原体Colletotrichum trifolii以及几种真菌提取物的根，但只有短暂的菌根定殖。当在根中组成型表达时，SP7导致较高的菌根化，同时降低C.三叶草介导的防御反应。此外，SP7在稻瘟病菌中的表达减轻了根腐烂症状。两者合计，这些结果表明，SP7是一个效应，有助于发展AM真菌在根部的生物营养状态，通过抵消植物免疫程序。
Biotrophic fungi interacting with plants establish long-term relationships with their hosts to fulfill their life cycles. In contrast to necrotrophs, they need to contend with the defense mechanisms of the plant to develop within the host and feed on living cells [1]. It is generally accepted that microbial pathogens produce and deliver a myriad of effector proteins to hijack the cellular program of their hosts [1-5]. Arbuscular mycorrhizal (AM) fungi are the most widespread biotrophs of plant roots [6]. We investigated whether AM fungi use effector proteins to short-circuit the plant defense program. Here we show that Glomus intraradices secretes a protein, SP7, that interacts with the pathogenesis-related transcription factor ERF19 in the plant nucleus. ERF19 is highly induced in roots by the fungal pathogen Colletotrichum trifolii as well as by several fungal extracts, but only transiently during mycorrhiza colonization. When constitutively expressed in roots, SP7 leads to higher mycorrhization while reducing the levels of C. trifolii-mediated defense responses. Furthermore, expression of SP7 in the rice blast fungus Magnaporthe oryzae attenuates root decay symptoms. Taken together, these results suggest that SP7 is an effector that contributes to develop the biotrophic status of AM fungi in roots by counteracting the plant immune program.