Soil and Water Science Department, University of Florida-IFAS, Gainesville 32610 USA.
Mol Plant Microbe Interact. 2010 Mar;23(3):273-82. doi: 10.1094/MPMI-23-3-0273.
Genomes of Salmonella enterica isolates, including those linked to outbreaks of produce-associated gastroenteritis, contain sdiA, which encodes a receptor of N-acyl homoserine lactones (AHL). AHL are the quorum-sensing signals used by bacteria to coordinately regulate gene expression within -their populations. Because S. enterica does not produce its own AHL, SdiA is hypothesized to function in the interspecies cross-talk with AHL-producing bacteria. Under laboratory conditions, S. enterica responded to AHL from phytobacteria by upregulating expression of srgE. AHL-dependent expression of srgE required a functional sdiA. Essentially, no sdiA-dependent resolution of the srgE recombinase-based (RIVET) reporter was observed inside a soft rot formed on a tomato by an AHL-producing strain of Pectobacterium carotovorum. The results of the control experiments suggest that sdiA is not expressed inside tomato, pepper, green onion, or carrot affected by the soft rot, and the lack of sdiA expression in planta prevents Salmonella spp. from responding to AHL. Despite its inability to detect and respond to AHL during colonization of soft rots, S. enterica reached higher final cell numbers inside a tomato soft rot compared with its growth in intact tomato fruit. The synergistic effect was the strongest under the conditions that are typical for the Florida fall/winter production season.
肠沙门氏菌分离株的基因组，包括与农产品相关的胃肠炎暴发有关的分离株，含有 sdiA，它编码 N-酰基高丝氨酸内酯（AHL）的受体。AHL 是细菌用于协调其群体内基因表达的群体感应信号。由于肠沙门氏菌本身不产生自己的 AHL，因此推测 SdiA 在与产生 AHL 的细菌的种间交流中发挥作用。在实验室条件下，肠沙门氏菌通过上调 srgE 的表达对植物细菌的 AHL 作出反应。srgE 的 AHL 依赖性表达需要功能性 sdiA。基本上，在由产 AHL 的果胶杆菌引起的软腐病形成于番茄内部时，没有观察到基于 srgE 重组酶的（RIVET）报告基因的 sdiA 依赖性解析。对照实验的结果表明，在受软腐病影响的番茄、辣椒、葱或胡萝卜内部，sdiA 没有表达，植物中 sdiA 的缺乏阻止了沙门氏菌对 AHL 的反应。尽管在软腐病定植期间无法检测和响应 AHL，但与完整番茄果实中的生长相比，肠沙门氏菌在番茄软腐病内部达到了更高的最终细胞数。在佛罗里达州秋季/冬季生产季节的典型条件下，协同效应最强。
