Plant methyl salicylate induces defense responses in the rhizobacterium Bacillus subtilis
Plant methyl salicylate induces defense responses in the rhizobacterium Bacillus subtilis
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DOI：
10.1111/1462-2920.12613
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发表时间：
2015-04-01
影响因子：
5.1
通讯作者：
Kobayashi, Kazuo
中科院分区：
文献类型：
--
作者：
Kobayashi, Kazuo
枯草芽孢杆菌是一种促进植物生长和健康的根际细菌。在固体培养基上培养具有连根拔起的杂草的B.subtilis，在植物附近的菌落上产生褶状结构。为了测试植物是否发出影响B.subtilis菌落形态的信号，我们检查了植物相关化合物对菌落形态的影响。枯草芽孢杆菌特异性地响应水杨酸甲酯形成粘液样菌落，水杨酸甲酯是响应病原体感染而释放的植物防御信号。水杨酸甲酯通过刺激聚谷氨酸的生物合成诱导粘液样集落形成，从而形成封闭的胶囊，保护细胞免受抗微生物化合物的影响。多聚谷氨酸的合成依赖于DegS-DegU双组分调控系统，该系统激活DegSU依赖的基因转录以响应水杨酸甲酯。枯草芽孢杆菌没有诱导植物水杨酸甲酯的生产，表明水杨酸甲酯在根际最可能的来源是病原体感染的植物。水杨酸甲酯诱导B.subtilis生物合成抗生素bacilysin和fengycin，其中fengycin对植物病原真菌尖孢镰刀菌表现出抑制活性。我们认为，B.subtilis可能通过水杨酸甲酯感知植物受到病原菌的攻击，并表达保护B.subtilis和根际寄主植物的防御反应。
Bacillus subtilis is a rhizobacterium that promotes plant growth and health. Cultivation of B.subtilis with an uprooted weed on solid medium produced pleat-like architectures on colonies near the plant. To test whether plants emit signals that affect B.subtilis colony morphology, we examined the effect of plant-related compounds on colony morphology. Bacillussubtilis formed mucoid colonies specifically in response to methyl salicylate, which is a plant-defense signal released in response to pathogen infection. Methyl salicylate induced mucoid colony formation by stimulating poly--glutamic acid biosynthesis, which formed enclosing capsules that protected the cells from exposure to antimicrobial compounds. Poly--glutamic acid synthesis depended on the DegS-DegU two-component regulatory system, which activated DegSU-dependent gene transcription in response to methyl salicylate. Bacillus subtilis did not induce plant methyl salicylate production, indicating that the most probable source of methyl salicylate in the rhizosphere is pathogen-infected plants. Methyl salicylate induced B.subtilis biosynthesis of the antibiotics bacilysin and fengycin, the latter of which exhibited inhibitory activity against the plant pathogenic fungus Fusarium oxysporum. We propose that B.subtilis may sense plants under pathogen attack via methyl salicylate, and express defense responses that protect both B.subtilis and host plants in the rhizosphere.