Two stripe rust effectors impair wheat resistance by suppressing import of host Fe-S protein into chloroplasts
Two stripe rust effectors impair wheat resistance by suppressing import of host Fe-S protein into chloroplasts
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DOI：
10.1093/plphys/kiab434
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发表时间：
2021-09-16
期刊：
影响因子：
7.4
通讯作者：
Wang，Xiaojie
中科院分区：
文献类型：
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作者：
Wang，Xiaodong;Zhai，Tong;Wang，Xiaojie
来自植物病原体的几种效应子通常靶向各种细胞器以干扰植物防御，并且它们通常含有指导它们易位到细胞器（例如叶绿体）中的序列。在这项研究中，我们的特点是一个不同的机制效应攻击小麦叶绿体（小麦）。小麦条锈菌（Pucciniastriiformisf. Pst、Pst_4和Pst_5抑制拟南芥介导的细胞死亡和植物免疫反应，如胼胝质沉积和活性氧（ROS）积累。这两个效应子的基因沉默诱导了对Pst的显著抗性，表明这两个效应子都是Pst的毒力因子。虽然这两个效应子的序列相似性较低，且缺乏叶绿体转运肽，但它们都与细胞质中的TaISP（小麦细胞色素b 6-f复合体铁硫亚基，一种由核基因编码的叶绿体蛋白）相互作用。TaISP基因的沉默降低了小麦对外源Pstand的抗性，导致活性氧的积累减少。TaISP的异源表达增强了本氏烟草中叶绿体来源的活性氧积累。N. benthamiana和western blot分析表明，两种效应子均抑制TaISP进入叶绿体。我们的结论是，这些活体营养真菌效应抑制植物防御破坏叶绿体蛋白的分选，从而限制主机ROS积累和促进真菌致病性。
Several effectors from phytopathogens usually target various cell organelles to interfere with plant defenses, and they generally contain sequences that direct their translocation into organelles, such as chloroplasts. In this study, we characterized a different mechanism for effectors to attack chloroplasts in wheat (Triticum aestivum). Two effectors fromPuccinia striiformisf. sp.tritici(Pst), Pst_4, and Pst_5, inhibit Bax-mediated cell death and plant immune responses, such as callose deposition and reactive oxygen species (ROS) accumulation. Gene silencing of the two effectors induced significant resistance toPst, demonstrating that both effectors function as virulence factors ofPst. Although these two effectors have low sequence similarities and lack chloroplast transit peptides, they both interact with TaISP (wheat cytochromeb6–f complex iron–sulfur subunit, a chloroplast protein encoded by nuclear gene) in the cytoplasm. Silencing ofTaISPimpaired wheat resistance to avirulentPstand resulted in less accumulation of ROS. Heterogeneous expression of TaISP enhanced chloroplast-derived ROS accumulation inNicotiana benthamiana. Co-localization inN. benthamianaand western blot assay of TaISP content in wheat chloroplasts show that both effectors suppressed TaISP from entering chloroplasts. We conclude that these biotrophic fungal effectors suppress plant defenses by disrupting the sorting of chloroplast protein, thereby limiting host ROS accumulation and promoting fungal pathogenicity.