Arabidopsis PECTIN METHYLESTERASEs Contribute to Immunity against Pseudomonas syringae
Arabidopsis PECTIN METHYLESTERASEs Contribute to Immunity against Pseudomonas syringae
复制标题
DOI：
10.1104/pp.113.227637
复制
发表时间：
2014-02-01
期刊：
影响因子：
7.4
通讯作者：
Glazebrook, Jane
中科院分区：
文献类型：
--
作者：
Bethke, Gerit;Grundman, Rachael E.;Glazebrook, Jane
果胶是双子叶细胞壁的主要成分，在高尔基体中以高度甲基化的形式合成，并在输出到细胞壁时被果胶甲基酯酶(PME)部分脱酯。PME活性对坏死性真菌病原菌灰霉病菌的致病力有重要影响。在这里，我们研究了拟南芥PME在模式触发免疫中的作用，以及对坏死性真菌油菜链格孢菌和细菌半生物营养菌花叶假单胞菌斑点假单胞菌ES4326(PMA ES4326)的免疫应答。在模式触发免疫期间和接种任一病原菌后，植物PME活性均增加。病原菌处理后PME活性的增加伴随着果胶甲酯化反应的减少。病原菌诱导的PME活性不需要水杨酸或乙烯信号，而依赖于茉莉酸信号。在甘蓝型油菜诱导的情况下，乙烯反应因子，而不是茉莉酸信号的MYC2分支参与了PME活性的诱导，而在PMA ES4326诱导的情况下，两个分支都起到了作用。拟南芥中有66个PME基因，这表明存在着广泛的遗传冗余。然而，经过筛选的Pme单、双、三和四倍突变体使PMA ES4326的生长显著高于野生型植物，这表明Pme在抗病中发挥了作用。在这些PME突变体中没有检测到总PME活性的下降，这表明免疫的决定因素不是总PME活性，而是PME的一些特定效应，如果胶甲酯化模式的变化。
Pectins, major components of dicot cell walls, are synthesized in a heavily methylesterified form in the Golgi and are partially deesterified by pectin methylesterases (PMEs) upon export to the cell wall. PME activity is important for the virulence of the necrotrophic fungal pathogen Botrytis cinerea. Here, the roles of Arabidopsis PMEs in pattern-triggered immunity and immune responses to the necrotrophic fungus Alternaria brassicicola and the bacterial hemibiotroph Pseudomonas syringae pv maculicola ES4326 (Pma ES4326) were studied. Plant PME activity increased during pattern-triggered immunity and after inoculation with either pathogen. The increase of PME activity in response to pathogen treatment was concomitant with a decrease in pectin methylesterification. The pathogen-induced PME activity did not require salicylic acid or ethylene signaling, but was dependent on jasmonic acid signaling. In the case of induction by A. brassicicola, the ethylene response factor, but not the MYC2 branch of jasmonic acid signaling, contributed to induction of PME activity, whereas in the case of induction by Pma ES4326, both branches contributed. There are 66 PME genes in Arabidopsis, suggesting extensive genetic redundancy. Nevertheless, selected pme single, double, triple and quadruple mutants allowed significantly more growth of Pma ES4326 than wild-type plants, indicating a role of PMEs in resistance to this pathogen. No decreases in total PME activity were detected in these pme mutants, suggesting that the determinant of immunity is not total PME activity; rather, it is some specific effect of PMEs such as changes in the pattern of pectin methylesterification.