Mutations in PMR5 result in powdery mildew resistance and altered cell wall composition
Mutations in PMR5 result in powdery mildew resistance and altered cell wall composition
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DOI：
10.1111/j.1365-313x.2004.02264.x
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发表时间：
2004-12-01
期刊：
影响因子：
7.2
通讯作者：
Somerville, SC
中科院分区：
文献类型：
--
作者：
Vogel, JP;Raab, TK;Somerville, SC
白粉病和其他专性生物营养型病原体高度适应其宿主，并且通常显示出有限的宿主范围。这种宿主特化的一个方面可能是穿透宿主细胞壁，这是感染的主要障碍。pmr 5基因的突变使拟南芥对白粉病物种白粉病菌（Erysiphe cichoracearum）和东方白粉病菌（Erysiphe orontii）具有抗性，但对不相关的病原体假单胞菌（Pseudomonaseringae）或霜霉（Peronospora parasitica）没有抗性。PMR 5基因是植物特异性功能未知基因的大家族。PMR 5介导的抗性不需要通过水杨酸或茉莉酸/乙烯防御途径的信号传导，这表明该突变体中的抗性可能是由于易感因子的丧失或由于新型防御形式的激活。基于傅立叶变换红外分析，pmr 5细胞壁富含果胶，并表现出相对于野生型细胞壁果胶修饰程度降低。此外，突变体具有较小的细胞，表明细胞扩增缺陷。一个双突变体与pmr 6（糖基磷脂酰肌醇锚定的果胶裂解酶样基因缺陷）表现出强烈的增加，总糖醛酸含量和更严重的减少的大小，相对于单突变体，这表明这两个基因影响果胶的组合物，直接或间接，通过不同的机制。这两个突变体突出了宿主细胞壁在植物-微生物相互作用中的重要性。
Powdery mildews and other obligate biotrophic pathogens are highly adapted to their hosts and often show limited host ranges. One facet of such host specialization is likely to be penetration of the host cell wall, a major barrier to infection. A mutation in the pmr5 gene rendered Arabidopsis resistant to the powdery mildew species Erysiphe cichoracearum and Erysiphe orontii, but not to the unrelated pathogens Pseudomonas syringae or Peronospora parasitica. PMR5 belongs to a large family of plant-specific genes of unknown function. pmr5-mediated resistance did not require signaling through either the salicylic acid or jasmonic acid/ethylene defense pathways, suggesting resistance in this mutant may be due either to the loss of a susceptibility factor or to the activation of a novel form of defense. Based on Fourier transform infrared analysis, the pmr5 cell walls were enriched in pectin and exhibited a reduced degree of pectin modification relative to wild-type cell walls. In addition, the mutant had smaller cells, suggesting a defect in cell expansion. A double mutant with pmr6 (defective in a glycosylphosphatidylinositol-anchored pectate lyase-like gene) exhibited a strong increase in total uronic acid content and a more severe reduction in size, relative to the single mutants, suggesting that the two genes affect pectin composition, either directly or indirectly, via different mechanisms. These two mutants highlight the importance of the host cell wall in plant-microbe interactions.