Chemoperception of Specific Amino Acids Controls Phytopathogenicity in Pseudomonas syringae pv. tomato
Chemoperception of Specific Amino Acids Controls Phytopathogenicity in Pseudomonas syringae pv. tomato
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DOI：
10.1128/mbio.01868-19
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发表时间：
2019-09-01
期刊：
影响因子：
6.4
通讯作者：
Lopez-Solanilla, Emilia
中科院分区：
文献类型：
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作者：
Paul Cerna-Vargas, Jean;Santamaria-Hernando, Saray;Lopez-Solanilla, Emilia
趋化性与细菌在植物中的致病性有关，并被发现促进细菌通过气孔和伤口进入。然而，关于参与这一过程的植物信号的知识很少。我们已经使用紫丁香假单胞菌解决了这个问题。番茄是一种引起番茄细菌性斑点的叶面病原体。我们证明了化学感受器紫丁香P.syringae PV.番茄PSCA(PsPto-PSCA)特异性高亲和力识别L-天冬氨酸、L-谷氨酸和D-天冬氨酸。化学受体基因的突变在很大程度上降低了对这些配体的趋化能力，但也改变了循环双GMP(c-di-GMP)水平、生物膜的形成和运动性，表明不同的化学感觉通路之间存在串扰。此外，PsPto-PscA突变株对番茄的致病力也有所降低。天冬氨酸和谷氨酸是植物中含量最丰富的氨基酸，特别是在西红柿质外体中，我们推测这种受体可能已经进化到特异性地识别这些化合物，以促进细菌进入植物。对野生型菌株的感染分析表明，饱和浓度的D-Asp的存在也降低了细菌的毒力。有大量证据表明，趋化性是植物病原菌有效致病的关键。然而，关于特定的细菌化学感受器和它们所感知的特定植物信号的信息很少。我们的工作表明，植物病原菌紫丁香假单胞菌。番茄不仅通过感受植物体内丰富的氨基酸天冬氨酸和谷氨酸来调节植物的趋化性，还可以控制其致病性。我们描述了PsPto-PSCA化学受体对L、D-天冬氨酸和L-Glu的感知的特异性，以及这种感知参与了致病相关性状的调节。此外，饱和浓度的D-Asp降低了细菌的毒力，因此我们提出，配体介导的关键化学受体的干扰可能是控制毒力的另一种策略。
Chemotaxis has been associated with the pathogenicity of bacteria in plants and was found to facilitate bacterial entry through stomata and wounds. However, knowledge regarding the plant signals involved in this process is scarce. We have addressed this issue using Pseudomonas syringae pv. tomato, which is a foliar pathogen that causes bacterial speck in tomato. We show that the chemoreceptor P. syringae pv. tomato PscA (PsPto-PscA) recognizes specifically and with high affinity L-Asp, L-Glu, and D-Asp. The mutation of the chemoreceptor gene largely reduced chemotaxis to these ligands but also altered cyclic di-GMP (c-di-GMP) levels, biofilm formation, and motility, pointing to cross talk between different chemosensory pathways. Furthermore, the PsPto-PscA mutant strain showed reduced virulence in tomato. Asp and Glu are the most abundant amino acids in plants and in particular in tomato apoplasts, and we hypothesize that this receptor may have evolved to specifically recognize these compounds to facilitate bacterial entry into the plant. Infection assays with the wild-type strain showed that the presence of saturating concentrations of D-Asp also reduced bacterial virulence.IMPORTANCE There is substantive evidence that chemotaxis is a key requisite for efficient pathogenesis in plant pathogens. However, information regarding particular bacterial chemoreceptors and the specific plant signal that they sense is scarce. Our work shows that the phytopathogenic bacterium Pseudomonas syringae pv. tomato mediates not only chemotaxis but also the control of pathogenicity through the perception of the plant abundant amino acids Asp and Glu. We describe the specificity of the perception of L- and D-Asp and L-Glu by the PsPto-PscA chemoreceptor and the involvement of this perception in the regulation of pathogenicity-related traits. Moreover, a saturating concentration of D-Asp reduces bacterial virulence, and we therefore propose that ligand-mediated interference of key chemoreceptors may be an alternative strategy to control virulence.