PLoS Pathogens:南京农业大学窦道龙研究组发表疫霉菌破坏植物免疫

2015年12月29日，国际病原菌顶级学术杂志《PLoS Pathogens》在线发表了南京农业大学植物保护学院窦道龙教授带领的作物疫病研究团队一项最新研究成果。论文题为“An Oomycete CRN Effector Reprograms expression of Plant HSP Genes by Targeting their Promoters”。植保学院博士生宋天巧为第一作者，窦道龙教授为通讯作者，王源超教授与张美祥博士等人也参与了本研究。

疫霉菌通过产生效应因子来破坏植物的抗性造成侵染;植物为了防御，进化出抗病基因来识别关键的效应因子，从而介导植物抗性的发生;在生产上由于单一抗病基因的大量使用，病原菌又进化出新的效应因子来逃脱抗病基因的识别，造成作物抗性丢失和病害流行成灾，因此效应因子是病原菌致病成灾和植物抗性利用的关键要素。本研究发现疫霉菌有一类具有结合寄主DNA活性的效应因子，该效应因子通过与寄主基因启动子结合干扰寄主防卫相关基因的表达，从而破坏植物抗性。

研究首次从动植物病原真菌与卵菌中发现具有结合寄主DNA活性的效应因子，该发现拓展了科学家对病原菌与植物协同进化的认识，对了解病害发生与成灾具有重要理论价值，为病害防控技术的发展奠定了基础。

An Oomycete CRN Effector Reprograms Expression of plant HSP Genes by Targeting their Promoters

原文摘要：

Oomycete pathogens produce a large number of CRN effectors to manipulate plant immune responses and promote infection. However, their functional mechanisms are largely unknown. Here, we identified a Phytophthora sojae CRN effector PsCRN108 which contains a putative DNA-binding helix-hairpin-helix (HhH) motif and acts in the Plant Cell nucleus. Silencing of thePsCRN108 gene reduced P. sojae virulence to soybean, while expression of the gene inNicotiana benthamiana and Arabidopsis thaliana enhanced plant susceptibility to P. capsici. Moreover, PsCRN108 could inhibit expression of HSP genes in A. thaliana, N. benthamianaand soybean. Both the HhH motif and nuclear localization signal of this effector were required for its contribution to virulence and its suppression of HSP gene expression. Furthermore, we found that PsCRN108 targeted HSP promoters in an HSE- and HhH motif-dependent manner. PsCRN108 could inhibit the association of the HSE with the plant heat shock transcription factor AtHsfA1a, which initializes HSP gene expression in response to stress. Therefore, our data support a role for PsCRN108 as a nucleomodulin in down-regulating the expression of plant defense-related genes by directly targeting specific plant promoters.

DOI:10.1371/jouRNAl.ppat.1005348

作者：窦道龙