Specific bacterial suppressors of MAMP signaling upstream of MAPKKK in Arabidopsis innate immunity
Specific bacterial suppressors of MAMP signaling upstream of MAPKKK in Arabidopsis innate immunity
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DOI：
10.1016/j.cell.2006.02.047
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发表时间：
2006-05-05
期刊：
影响因子：
64.5
通讯作者：
Sheen, Jen
中科院分区：
文献类型：
--
作者：
He, Ping;Shan, Libo;Sheen, Jen
植物和动物拥有预防感染的先天免疫系统，并且是大多数潜在病原体的有效“非宿主”。植物非宿主免疫的分子机制仍不清楚。在拟南芥中，非宿主/非致病性丁香假单胞菌维持，但致病性丁香假单胞菌抑制早期 MAMP（微生物相关分子模式）标记基因激活。我们对毒力因子进行了基于细胞的遗传筛选，并确定 AvrPto 和 AvrPtoB 是早期防御基因转录和 MAP 激酶 (MAPK) 信号传导的有效且独特的抑制剂。与哺乳动物病原体的效应器不同，AvrPto 和 AvrPtoB 在与受体相连的质膜处拦截 MAPKKK 上游的多个 MAMP 介导的信号传导。在转基因拟南芥中，AvrPto 阻断早期 MAMP 信号传导并使非宿主丁香假单胞菌生长。从致病性丁香假单胞菌中删除 avrPto 和 avrPtoB 可降低其毒力。这些研究揭示了 MAMP 信号在非宿主免疫中的基本作用，以及来自病原菌的 III 型效应子的新作用。
Plants and animals possess innate immune systems to prevent infections and are effectively "nonhosts" for most potential pathogens. The molecular mechanisms underlying nonhost immunity in plants remain obscure. In Arabidopsis, nonhost/nonpathogenic Pseudomonas syringae sustains but pathogenic P. syringae suppresses early MAMP (microbe-associated molecular pattern) marker-gene activation. We performed a cell-based genetic screen of virulence factors and identified AvrPto and AvrPtoB as potent and unique suppressors of early-defense gene transcription and MAP kinase (MAPK) signaling. Unlike effectors of mammalian pathogens, AvrPto and AvrPtoB intercept multiple MAMP-mediated signaling upstream of MAPKKK at the plasma membrane linked to the receptor. In transgenic Arabidopsis, AvrPto blocks early MAMP signaling and enables nonhost P. syringae growth. Deletions of avrPto and avrPtoB from pathogenic P. syringae reduce its virulence. The studies reveal a fundamental role of MAMP signaling in nonhost immunity, and a novel action of type III effectors from pathogenic bacteria.