College of Plant Protection, Southwest University, Chongqing 400715, China.
Chongqing Key Laboratory of Scientific Utilization of Tobacco Resources, Chongqing 400060, China.
Pestic Biochem Physiol. 2023 Aug;194:105455. doi: 10.1016/j.pestbp.2023.105455. Epub 2023 May 11.
Nanoparticles have recently been employed as a new strategy to act as bactericides in agricultural applications. However, the effects and mechanisms of foliar deposition of nanoparticles on bacterial pathogens, plant physiology and particularly plant immunity have not been sufficiently understood. Here, we investigated the effects and mechanisms of ZnO NPs in controlling of tobacco wildfire caused by Pseudomonas syringae pv. tabaci, through the comprehensive analysis of biological changes of both bacteria and plants. The global gene expression changes of Pseudomonas syringae pv. tabaci supported that the functions of "protein secretion", "membrane part", "signal transducer activity", "locomotion", "chemotaxis" and "taxis" in bacteria, as well as the metabolic pathways of "bacterial chemotaxis", "two-component system", "biofilm formation", "ABC transporters" and "valine, leucine and isoleucine degradation" were significantly down-regulated by ZnO NPs. Correspondingly, we reconfirmed that the cell envelope structure, biofilm and motility of Pseudomonas syringae pv. tabaci were directly disrupted or suppressed by ZnO NPs. Different from completely killing Pseudomonas syringae pv. tabaci, ZnO NPs (0.5 mg/mL) potentially improved plant growth and immunity through enzymatic activity and global molecular response analysis. Furthermore, the changes of gene expression in ABA signaling pathway, ABA concentration and stomatal aperture all supported that ZnO NPs can specifically stimulate stomatal immunity, which is important to defend bacterial infection. Taken together, we proposed that both the inhibition or damage of motility, biofilm, metabolisms, virulence and cell envelope on P. syringae pv. tabaci, and the activation of the stomatal immunity formed two-layered antibacterial mechanisms of ZnO NPs on phytopathogenic bacteria.
纳米颗粒最近被用作农业应用中作为杀菌剂的一种新策略。然而，叶部沉积纳米颗粒对细菌病原体、植物生理学，特别是植物免疫的影响和机制还没有得到充分的理解。在这里，我们通过综合分析细菌和植物的生物变化，研究了 ZnO NPs 对由丁香假单胞菌引起的烟草野火的控制作用。假单胞菌 pv. tabaci 的全基因表达变化表明，细菌的“蛋白质分泌”、“膜部分”、“信号转导活性”、“运动”、“趋化性”和“向性”以及“细菌趋化性”、“双组分系统”、“生物膜形成”、“ABC 转运体”和“缬氨酸、亮氨酸和异亮氨酸降解”的代谢途径的功能明显受到 ZnO NPs 的下调。相应地，我们再次证实 ZnO NPs 直接破坏或抑制了丁香假单胞菌 pv. tabaci 的细胞包膜结构、生物膜和运动性。与完全杀死丁香假单胞菌 pv. tabaci 不同，ZnO NPs（0.5mg/mL）通过酶活性和全分子反应分析潜在地促进了植物的生长和免疫。此外，ABA 信号通路、ABA 浓度和气孔开度的基因表达变化均支持 ZnO NPs 可以特异性地刺激气孔免疫，这对于抵御细菌感染很重要。综上所述，我们提出 ZnO NPs 对丁香假单胞菌 pv. tabaci 的运动性、生物膜、代谢、毒力和细胞包膜的抑制或损害，以及气孔免疫的激活，形成了 ZnO NPs 对植物病原菌的双层抗菌机制。
