Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, USA.
Center for Medical, Agricultural, and Veterinary Entomology, U.S. Department of Agriculture-Agricultural Research Service, Gainesville, FL, USA.
Sci Rep. 2022 May 4;12(1):7313. doi: 10.1038/s41598-022-11456-6.
Salmonella enterica is ubiquitous in the plant environment, persisting in the face of UV stress, plant defense responses, desiccation, and nutrient limitation. These fluctuating conditions of the leaf surface result in S. enterica population decline. Biomultipliers, such as the phytopathogenic bacterium Xanthomonas hortorum pv. gardneri (Xhg), alter the phyllosphere to the benefit of S. enterica. Specific Xhg-dependent changes to this niche that promote S. enterica persistence remain unclear, and this work focuses on identifying factors that lead to increased S. enterica survival on leaves. Here, we show that the Xhg transcription activator-like effector AvrHah1 is both necessary and sufficient for increased survival of S. enterica on tomato leaves. An Xhg avrHah1 mutant fails to influence S. enterica survival while addition of avrHah1 to X. vesicatoria provides a gain of function. Our results indicate that although Xhg stimulates a robust immune response from the plant, AvrHah1 is not required for these effects. In addition, we demonstrate that cellular leakage that occurs during disease is independent of AvrHah1. Investigation of the interaction between S. enterica, Xhg, and the plant host provides information regarding how an inhospitable environment changes during infection and can be transformed into a habitable niche.
肠炎沙门氏菌在植物环境中无处不在，能在面对 UV 应激、植物防御反应、干燥和营养限制时存活下来。叶片表面的这些波动条件导致肠炎沙门氏菌数量下降。生物倍增剂，如植物病原菌黄单胞菌（Xanthomonas hortorum pv. gardneri）（Xhg），改变了叶际环境，有利于肠炎沙门氏菌的生存。促进肠炎沙门氏菌持续存在的特定依赖于 Xhg 的小生境变化尚不清楚，这项工作重点是确定导致肠炎沙门氏菌在叶片上存活能力增强的因素。在这里，我们表明 Xhg 转录激活子样效应因子 AvrHah1 对于肠炎沙门氏菌在番茄叶片上的存活增加是必要和充分的。Xhg avrHah1 突变体不能影响肠炎沙门氏菌的存活，而添加 avrHah1 到 X. vesicatoria 则提供了功能获得。我们的结果表明，尽管 Xhg 刺激植物产生强烈的免疫反应，但 AvrHah1 不是这些作用所必需的。此外，我们证明了在疾病过程中发生的细胞渗漏与 AvrHah1 无关。对肠炎沙门氏菌、Xhg 和植物宿主之间的相互作用的研究提供了有关在感染过程中不适合的环境如何发生变化并可以转化为可居住小生境的信息。
