A Massive Expansion of Effector Genes Underlies Gall-Formation in the Wheat Pest Mayetiola destructor
A Massive Expansion of Effector Genes Underlies Gall-Formation in the Wheat Pest Mayetiola destructor
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DOI：
10.1016/j.cub.2014.12.057
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发表时间：
2015-03-02
期刊：
影响因子：
9.2
通讯作者：
Richards, Stephen
中科院分区：
文献类型：
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作者：
Zhao, Chaoyang;Escalante, Lucia Navarro;Richards, Stephen
形成瘿的节肢动物是高度特化的食草动物，与它们的宿主结合，产生具有独特形态的扩展表型[1]。其中许多在经济上具有重要意义，另一些则提高了我们对生态学和适应性辐射的理解[2]。然而，这些节肢动物用于诱导植物虫瘿的机制知之甚少。我们对黑森蝇（Mayetiola destructor;双翅目：Cecidomyiidae）的基因组进行了测序，黑森蝇是一种植物寄生瘿蚊和小麦害虫（小麦属），目的是确定有助于其植物寄生生活方式的基因修饰。在几种适应性修饰中，我们发现了一个潜在的效应蛋白的广阔的水库。在20,163个预测的基因模型中，近5%与M.破坏者幼虫的唾液腺。在其他生物体中没有序列相似性的基因中发现了另外466个推定的效应子。最大的已知节肢动物基因家族（家族SSGP-71）也被发现在效应水库。SSGP-71蛋白与其他蛋白缺乏序列同源性，但其结构类似于植物中的泛素E3连接酶和植物病原细菌中的E3-连接酶模拟效应子。SSGP-71蛋白和小麦Skp蛋白在体内相互作用。不同SSGP-71基因的突变避免了由小麦抗性基因H6和H9指导的效应子触发的免疫。结果表明，效应因子是节肢动物诱导植物虫瘿形成的主要因子。
Gall-forming arthropods are highly specialized herbivores that, in combination with their hosts, produce extended phenotypes with unique morphologies [1]. Many are economically important, and others have improved our understanding of ecology and adaptive radiation [2]. However, the mechanisms that these arthropods use to induce plant galls are poorly understood. We sequenced the genome of the Hessian fly (Mayetiola destructor; Diptera: Cecidomyiidae), a plant parasitic gall midge and a pest of wheat (Triticum spp.), with the aim of identifying genic modifications that contribute to its plant-parasitic lifestyle. Among several adaptive modifications, we discovered an expansive reservoir of potential effector proteins. Nearly 5% of the 20,163 predicted gene models matched putative effector gene transcripts present in the M. destructor larval salivary gland. Another 466 putative effectors were discovered among the genes that have no sequence similarities in other organisms. The largest known arthropod gene family (family SSGP-71) was also discovered within the effector reservoir. SSGP-71 proteins lack sequence homologies to other proteins, but their structures resemble both ubiquitin E3 ligases in plants and E3-ligase-mimicking effectors in plant pathogenic bacteria. SSGP-71 proteins and wheat Skp proteins interact in vivo. Mutations in different SSGP-71 genes avoid the effector-triggered immunity that is directed by the wheat resistance genes H6 and H9. Results point to effectors as the agents responsible for arthropod-induced plant gall formation.