Broad-Spectrum Suppression of Innate Immunity Is Required for Colonization of Arabidopsis Roots by the Fungus Piriformospora indica
Broad-Spectrum Suppression of Innate Immunity Is Required for Colonization of Arabidopsis Roots by the Fungus Piriformospora indica
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DOI：
10.1104/pp.111.176446
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发表时间：
2011-06-01
期刊：
影响因子：
7.4
通讯作者：
Schaefer, Patrick
中科院分区：
文献类型：
--
作者：
Jacobs, Sophie;Zechmann, Bernd;Schaefer, Patrick
印度梨形孢是一种定植于根部的担子菌，赋予其宿主多种有益特征。该真菌在拟南芥 (Arabidopsis thaliana) 根中表现出生物营养生长期，随后是细胞死亡相关的定植阶段，据我们所知，这种定植策略尚未见报道。 P. indica 已经进化出了非凡的植物根定植能力。其广泛的宿主谱包括裸子植物和单子叶以及双子叶被子植物，这表明它具有绕过或抑制宿主免疫的有效机制。我们的工作结果表明，P. indica 面临着功能性的根免疫系统。此外，这种真菌不会逃避检测，而是会抑制由各种微生物相关分子模式引发的免疫力。这种抑制宿主免疫的能力在茉莉酸突变体茉莉酸不敏感1-1和茉莉酸抗性1-1中受到损害。显示组成型赤霉素 (GA) 反应的五重 DELLA 突变体和 GA 生物合成突变体 ga1-6（对于需要 1 的 GA）在细胞死亡相关阶段分别表现出较高和较低的定植程度，表明 P. indica 募集 GA 信号传导以帮助建立促凋亡根细胞定植。我们的研究表明，与病原体一样，共生体在根部面临着有效的先天免疫系统，并且定植的成功本质上取决于免疫抑制策略的演变。
Piriformospora indica is a root-colonizing basidiomycete that confers a wide range of beneficial traits to its host. The fungus shows a biotrophic growth phase in Arabidopsis (Arabidopsis thaliana) roots followed by a cell death-associated colonization phase, a colonization strategy that, to our knowledge, has not yet been reported for this plant. P. indica has evolved an extraordinary capacity for plant root colonization. Its broad host spectrum encompasses gymnosperms and monocotyledonous as well as dicotyledonous angiosperms, which suggests that it has an effective mechanism(s) for bypassing or suppressing host immunity. The results of our work argue that P. indica is confronted with a functional root immune system. Moreover, the fungus does not evade detection but rather suppresses immunity triggered by various microbe-associated molecular patterns. This ability to suppress host immunity is compromised in the jasmonate mutants jasmonate insensitive1-1 and jasmonate resistant1-1. A quintuple-DELLA mutant displaying constitutive gibberellin (GA) responses and the GA biosynthesis mutant ga1-6 (for GA requiring 1) showed higher and lower degrees of colonization, respectively, in the cell death-associated stage, suggesting that P. indica recruits GA signaling to help establish proapoptotic root cell colonization. Our study demonstrates that mutualists, like pathogens, are confronted with an effective innate immune system in roots and that colonization success essentially depends on the evolution of strategies for immunosuppression.