Pathogen effectors are virulence factors causing plant diseases. How the host targets of these effectors facilitate pathogen infection is largely unknown. An effector of Xanthomonas oryzae pv oryzae (Xoo) transcriptionally activates rice (Oryza sativa) susceptibility gene Xa13 to cause bacterial blight disease. Xa13 encodes an indispensable plasma membrane protein of the MtN3/saliva family, which is prevalent in eukaryotes with unknown biochemical function. We show that the XA13 protein cooperates with two other proteins, COPT1 and COPT5, to promote removal of copper from xylem vessels, where Xoo multiplies and spreads to cause disease. Copper, an essential micronutrient of plants and an important element for a number of pesticides in agriculture, suppresses Xoo growth. Xoo strain PXO99 is more sensitive to copper than other strains; its infection of rice is associated with activation of XA13, COPT1, and COPT5, which modulate copper redistribution in rice. The involvement of XA13 in copper redistribution has led us to propose a mechanism of bacterial virulence.
病原菌的效應(yīng)分子是導(dǎo)致植物發(fā)病的毒性因子。對于宿主是如何把這種促進(jìn)病原菌感染的效應(yīng)子作為靶標(biāo)的，目前還所知甚少。Xanthomonas oryzae （Xoo）的一個效應(yīng)子能轉(zhuǎn)錄激活感病基因Xa13表達(dá)，從而導(dǎo)致水稻白葉枯病發(fā)生。Xa13編碼屬于MtN3/saliva家族的一個不可或缺的質(zhì)膜蛋白，MtN3/saliva家族的蛋白在真核生物普遍存在，但是生化功能未知。作者的研究結(jié)果表明XA13和另外兩個蛋白COPT1和COPT5協(xié)作促進(jìn)銅從木質(zhì)部的移除（Xoo在木質(zhì)部擴(kuò)增和擴(kuò)散從而使植株發(fā)?。ｃ~是植物必需的微量元素，并且是農(nóng)業(yè)生產(chǎn)上使用的許多殺蟲劑的重要成分，能夠抑制Xoo的生長。Xoo小種PXO99比其他小種對銅更加敏感，在其感染水稻時伴隨著XA13、COPT1和COPT5的激活，這些蛋白可以調(diào)節(jié)水稻中銅的重新分配。XA13參與銅元素的重新分配幫助我們提出了細(xì)菌毒性的機(jī)理。