Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, U.S.A.
Mol Plant Microbe Interact. 2023 Jun;36(6):334-344. doi: 10.1094/MPMI-11-22-0239-R. Epub 2023 Jul 27.
causes bacterial wilt disease on diverse plant hosts. cells enter a host from soil or infested water through the roots, then multiply and spread in the water-transporting xylem vessels. Despite the low nutrient content of xylem sap, grows very well inside the host, using denitrification to respire in this hypoxic environment. growth in planta also depends on the successful deployment of protein effectors into host cells via a type III secretion system (T3SS). The T3SS is absolutely required for virulence, but it is metabolically costly and can trigger host defenses. Thus, the pathogen's success depends on optimized regulation of the T3SS. We found that a byproduct of denitrification, the toxic free-radical nitric oxide (NO), positively regulates the T3SS both in vitro and in planta. Using chemical treatments and mutants with altered NO levels, we show that the expression of a key T3SS regulator, , is induced by NO in culture. Analyzing the transcriptome of responding to varying levels of NO both in culture and in planta revealed that the T3SS and effectors were broadly upregulated with increasing levels of NO. This regulation was specific to the T3SS and was not shared by other stressors. Our results suggest that may experience an NO-rich environment in the plant host and that this NO contributes to the activation of the T3SS during infection. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
在多种植物宿主上引起细菌性萎蔫病。细菌从土壤或受感染的水中通过根部进入宿主，然后在输水的木质部导管中繁殖和扩散。尽管木质部汁液的营养含量低，但在宿主内部生长得非常好，通过反硝化作用在这种缺氧环境中呼吸。在植物体内的生长也依赖于通过 III 型分泌系统（T3SS）将蛋白效应器成功地部署到宿主细胞中。T3SS 对毒力绝对必要，但它代谢成本高，并能引发宿主防御。因此，病原体的成功取决于 T3SS 的优化调节。我们发现，反硝化的一种副产物，有毒自由基一氧化氮（NO），在体外和体内都能正向调节 T3SS。通过化学处理和改变 NO 水平的突变体，我们表明，关键 T3SS 调节剂的表达在培养物中被 NO 诱导。分析 对培养物和植物中不同水平的 NO 的转录组表明，T3SS 和效应器随着 NO 水平的增加而广泛上调。这种调节是特异性的，与其他胁迫因子无关。我们的结果表明，在植物宿主中，可能会经历一个富含 NO 的环境，而这种 NO 有助于感染过程中 T3SS 的激活。
