Cell-length heterogeneity: a population-level solution to growth/virulence trade-offs in the plant pathogen Dickeya dadantii
Cell-length heterogeneity: a population-level solution to growth/virulence trade-offs in the plant pathogen Dickeya dadantii
复制标题
DOI：
10.1371/journal.ppat.1007703
复制
发表时间：
2019-08-01
期刊：
影响因子：
6.7
通讯作者：
Zeng, Quan
中科院分区：
文献类型：
--
作者：
Cui, Zhouqi;Yang, Ching-Hong;Zeng, Quan
坏死性植物病原体从死亡的植物细胞中获取营养，这需要病原体分解植物细胞壁和组织结构。受感染的植物失去了组织完整性和功能性免疫力，使营养丰富的腐烂组织暴露在环境中。坏死营养菌成功引起继发感染（感染从最初感染的植物传播到附近未感染的植物）的一个挑战是在其他腐生菌到来之前有效地利用宿主释放的营养物质来建立一个庞大的种群。在本研究中，我们观察到在马铃薯块茎侵染过程中，在等基因群体中，坏死致病菌dadantii在细菌细胞长度上表现出异质性。部分细胞呈规整棒状（10 μ m）。短细胞多出现在健康组织和患病组织的交界面，在感染早期发生主动攻击和杀伤时，而丝状细胞多出现在感染后期。短细胞表达所有必要的毒力因子和运动性，而丝状细胞不参与毒力，不移动，对环境应激更敏感。然而，与短细胞相比，丝状细胞表现出代谢基因的上调和生长的增加，这可能有利于病原体建立继发感染所需的大量群体。这两个亚居群的分离取决于四磷酸鸟苷（ppGpp）的不同产量。当暴露于新鲜的块茎组织或独立的水，丝状细胞迅速转化为短毒细胞。本研究中发现的细胞长度异质性的病原体适应性为一些坏死细胞在感染期间如何平衡毒力和营养生长以最大化适应性提供了一个模型。
Necrotrophic plant pathogens acquire nutrients from dead plant cells, which requires the disintegration of the plant cell wall and tissue structures by the pathogen. Infected plants lose tissue integrity and functional immunity as a result, exposing the nutrient rich, decayed tissues to the environment. One challenge for the necrotrophs to successfully cause secondary infection (infection spread from an initially infected plant to the nearby uninfected plants) is to effectively utilize nutrients released from hosts towards building up a large population before other saprophytes come. In this study, we observed that the necrotrophic pathogen Dickeya dadantii exhibited heterogeneity in bacterial cell length in an isogenic population during infection of potato tuber. While some cells were regular rod-shape (10 mu m). Short cells tended to occur at the interface of healthy and diseased tissues, during the early stage of infection when active attacking and killing is occurring, while filamentous cells tended to form at a later stage of infection. Short cells expressed all necessary virulence factors and motility, whereas filamentous cells did not engage in virulence, were non-mobile and more sensitive to environmental stress. However, compared to the short cells, the filamentous cells displayed upregulated metabolic genes and increased growth, which may benefit the pathogens to build up a large population necessary for the secondary infection. The segregation of the two subpopulations was dependent on differential production of the alarmone guanosine tetraphosphate (ppGpp). When exposed to fresh tuber tissues or freestanding water, filamentous cells quickly transformed to short virulent cells. The pathogen adaptation of cell length heterogeneity identified in this study presents a model for how some necrotrophs balance virulence and vegetative growth to maximize fitness during infection.