Homologous RXLR effectors from Hyaloperonospora arabidopsidis and Phytophthora sojae suppress immunity in distantly related plants
Homologous RXLR effectors from Hyaloperonospora arabidopsidis and Phytophthora sojae suppress immunity in distantly related plants
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DOI：
10.1111/j.1365-313x.2012.05079.x
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发表时间：
2012-12-01
期刊：
影响因子：
7.2
通讯作者：
McDowell, John M.
中科院分区：
文献类型：
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作者：
Anderson, Ryan G.;Casady, Megan S.;McDowell, John M.
多种病原体分泌效应蛋白到植物细胞中以操纵宿主细胞过程。卵菌病原体含有由RXLR宿主细胞进入基序定义的预测效应基因的大量互补。拟南芥霜霉病菌（Hyaloperonospora arabidopsidis，Hpa）基因组中含有至少134个候选RXLR效应基因。这些基因中只有一小部分在疫霉属的相关卵菌中是保守的。在这里，我们描述了一个比较功能特性的HPA RXLR效应基因HaRxL96和同源基因，PsAvh163，从大豆（大豆）病原体大豆疫霉。HaRxL96和PsAvh163在感染的早期阶段被诱导，并携带足以使蛋白质摄取到植物细胞中的功能性RXLR基序。这两种效应子都能抑制大豆的免疫反应。HaRxL96抑制本氏烟草中的免疫，而PsAvh163诱导烟草中依赖于RAR 1和HSP 90.1的HR样细胞死亡反应。表达HaRxL96或PsAvh163的转基因拟南芥植物表现出对有毒和无毒Hpa的敏感性升高，以及响应于非致病性假单胞菌的胼胝质沉积降低。这两种效应子都干扰防御标记基因的诱导，但不影响水杨酸的生物合成。总之，这些实验表明，来自不同卵菌物种的进化保守效应子可以抑制与源病原体宿主不同的植物物种的免疫力。
Diverse pathogens secrete effector proteins into plant cells to manipulate host cellular processes. Oomycete pathogens contain large complements of predicted effector genes defined by an RXLR host cell entry motif. The genome of Hyaloperonospora arabidopsidis (Hpa, downy mildew of Arabidopsis) contains at least 134 candidate RXLR effector genes. Only a small subset of these genes is conserved in related oomycetes from the Phytophthora genus. Here, we describe a comparative functional characterization of the Hpa RXLR effector gene HaRxL96 and a homologous gene, PsAvh163, from the Glycine max (soybean) pathogen Phytophthora sojae. HaRxL96 and PsAvh163 are induced during the early stages of infection and carry a functional RXLR motif that is sufficient for protein uptake into plant cells. Both effectors can suppress immune responses in soybean. HaRxL96 suppresses immunity in Nicotiana benthamiana, whereas PsAvh163 induces an HR-like cell death response in Nicotiana that is dependent on RAR1 and Hsp90.1. Transgenic Arabidopsis plants expressing HaRxL96 or PsAvh163 exhibit elevated susceptibility to virulent and avirulent Hpa, as well as decreased callose deposition in response to non-pathogenic Pseudomonas syringae. Both effectors interfere with defense marker gene induction, but do not affect salicylic acid biosynthesis. Together, these experiments demonstrate that evolutionarily conserved effectors from different oomycete species can suppress immunity in plant species that are divergent from the source pathogen's host.