Xanthomonas translucenscommandeers the host rate-limiting step in ABA biosynthesis for disease susceptibility

First author: Zhao Peng; Affiliations: University of Florida (佛罗里达大学): Gainesville, USA

Corresponding author: Frank F. White

Plants are vulnerable to disease through pathogen manipulation of phytohormone levels, which otherwise regulate development, abiotic, and biotic responses. Here, we show that the wheat pathogen Xanthomonas translucens pv. undulosa elevates expression of the host gene encoding 9-cis-epoxycarotenoid dioxygenase (TaNCED-5BS), which catalyzes the rate-limiting step in the biosynthesis of the phytohormone abscisic acid and a component of a major abiotic stress-response pathway, to promote disease susceptibility. Gene induction is mediated by a type III transcription activator-like effector. The induction of TaNCED-5BS results in elevated abscisic acid levels, reduced host transpiration and water loss, enhanced spread of bacteria in infected leaves, and decreased expression of the central defense gene TaNPR1. The results represent an appropriation of host physiology by a bacterial virulence effector.

病原菌通过影响植物的激素水平使得寄主植物更加易感，而这些激素通常是被植物用来调控发育、生物和非生物胁迫响应的。本文中，作者的研究显示小麦黑颖病黄单胞菌通过提升寄主植物中9-顺式-环氧类胡萝卜素双加氧酶编码基因TaNCED-5BS的表达促进侵染，而该基因编码的酶是植物激素脱落酸生物合成的限速酶，一个非生物胁迫响应的主要途径。该基因诱导是由III型类转录激活效应物所介导的。TaNCED-5BS基因的诱导导致了脱落酸水平的提升，降低了寄主蒸腾作用和水分丢失，增强了病菌在侵染叶片中的扩散速度，并且降低了寄主植物中主要防御基因TaNPR1的表达。本文的研究结果揭示了一个细菌毒力效应物侵占寄主生理的案例。

通讯：Frank F. White (https://plantpath.ifas.ufl.edu/people/faculty-pages/frank-white/)

个人简介：1974年，威斯康星大学，学士；1981年，佛罗里达大学，博士。

研究方向：病原体/宿主之间关于病原体毒力、宿主易感性和耐药性的遗传基础。

doi: https://doi.org/10.1073/pnas.1911660116

Journal: PNAS

First Published: October 01, 2019