Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie "Charles Darwin," Sapienza Università di Roma, 00185 Rome, Italy.
Plant Physiol. 2011 Oct;157(2):804-14. doi: 10.1104/pp.111.174003. Epub 2011 Jul 29.
Mitogen-activated protein kinases (MAPKs) are fundamental components of the plant innate immune system. MPK3 and MPK6 are Arabidopsis (Arabidopsis thaliana) MAPKs activated by pathogens and elicitors such as oligogalacturonides (OGs), which function as damage-associated molecular patterns, and flg22, a well-known microbe-associated molecular pattern. However, the specific contribution of MPK3 and MPK6 to the regulation of elicitor-induced defense responses is not completely defined. In this work we have investigated the roles played by these MAPKs in elicitor-induced resistance against the fungal pathogen Botrytis cinerea. Analysis of single mapk mutants revealed that lack of MPK3 increases basal susceptibility to the fungus, as previously reported, but does not significantly affect elicitor-induced resistance. Instead, lack of MPK6 has no effect on basal resistance but suppresses OG- and flg22-induced resistance to B. cinerea. Overexpression of the AP2C1 phosphatase leads to impaired OG- and flg22-induced phosphorylation of both MPK3 and MPK6, and to phenotypes that recapitulate those of the single mapk mutants. These data indicate that OG- and flg22-induced defense responses effective against B. cinerea are mainly dependent on MAPKs, with a greater contribution of MPK6.
丝裂原活化蛋白激酶（MAPKs）是植物先天免疫系统的基本组成部分。MPK3 和 MPK6 是拟南芥（Arabidopsis thaliana）MAPKs，可被病原体和诱导剂如寡聚半乳糖醛酸（OGs）激活，OGs 作为损伤相关分子模式，而 flg22 是一种众所周知的微生物相关分子模式。然而，MPK3 和 MPK6 对诱导防御反应的具体贡献尚未完全确定。在这项工作中，我们研究了这些 MAPKs 在诱导剂诱导的对真菌病原体灰葡萄孢（Botrytis cinerea）抗性中的作用。对单个 mapk 突变体的分析表明，缺乏 MPK3 如先前报道的那样增加了对真菌的基础易感性，但对诱导抗性没有显著影响。相反，缺乏 MPK6 对基础抗性没有影响，但抑制了 OG 和 flg22 诱导的对 B. cinerea 的抗性。AP2C1 磷酸酶的过表达导致 OG 和 flg22 诱导的对 MPK3 和 MPK6 的磷酸化受损，并导致与单个 mapk 突变体相似的表型。这些数据表明，对 B. cinerea 有效的 OG 和 flg22 诱导的防御反应主要依赖于 MAPKs，其中 MPK6 的贡献更大。
