The bacterial alarmone (p)ppGpp is required for virulence and controls cell size and survival of Pseudomonas syringae on plants.
The bacterial alarmone (p)ppGpp is required for virulence and controls cell size and survival of Pseudomonas syringae on plants.
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DOI：
10.1111/1462-2920.12744
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发表时间：
2015-11
影响因子：
5.1
通讯作者：
Zhao Y
中科院分区：
文献类型：
--
作者：
Chatnaparat T;Li Z;Korban SS;Zhao Y
这种由第二信使(P)ppGpp介导的严格反应，导致在营养有限的条件下快速而大规模的转录重编程。在本研究中，研究了(P)ppGpp对紫丁香叶枯病菌毒力的影响。对丁香菌B728a(PssB728a)进行了研究。双突变体relA/Spot(PpGpp0)对菜豆的致病力完全减弱，细菌生长显著减弱，表明(P)ppGpp是紫丁香叶枯病菌完全致病所必需的。在ppGpp0突变体中，T3SS等毒力基因的表达降低。此外，ppGpp缺乏还会导致蜂群活动丧失、吡喃啶产量减少、对氧化胁迫和抗生素耐受性增加，以及利用γ-氨基丁酸的能力降低。当ppGpp水平升高时，PssB728a的细胞体积变小，而大多数ppGpp0突变体细胞在喷雾接种24 h后在植物表面不能存活，这表明ppGpp介导的严格反应暂时限制了细胞的生长，并可能通过限制细胞的生长来控制细胞在植物上的存活。这些结果表明ppGpp介导的严谨反应在紫丁香叶枯病菌的毒力和生存中起着核心作用，并表明ppGpp是调节PssB728a各种毒力性状的全局信号。
The stringent response, mediated by second messenger (p)ppGpp, results in swift and massive transcriptional reprogramming under nutrient limited conditions. In this study, the role of (p)ppGpp on virulence of P. syringae pv. syringae B728a (PssB728a) was investigated. The virulence of the relA/spoT (ppGpp0) double mutant was completely impaired on bean, and bacterial growth was significantly reduced, suggesting that (p)ppGpp is required for full virulence of P. syringae. Expression of T3SS and other virulence genes was reduced in ppGpp0 mutants. In addition, ppGpp deficiency resulted in loss of swarming motility, reduction of pyoverdine production, increased sensitivity to oxidative stress and antibiotic tolerance, as well as reduced ability to utilize γ-amino butyric acid. Increased levels of ppGpp resulted in reduced cell size of PssB728a when grown in a minimal medium and on plant surfaces, while most ppGpp0 mutant cells were not viable on plant surfaces 24 h after spray inoculation, suggesting that ppGpp-mediated stringent response temporarily limits cell growth, and might control cell survival on plants by limiting their growth. These results demonstrated that ppGpp-mediated stringent response plays a central role in P. syringae virulence and survival, and indicated that ppGpp serves as a global signal for regulating various virulence traits in PssB728a.