Plants accumulate Abscisic acid after Ralstonia solanacearum infection for enhanced dehydration tolerance and plant resistance

Yao Wang ¹ Shili Li ¹ Anbin Wang ¹ Xingjun Ma ¹ Ruiming Liang ¹ Liquan Zhu ² Min Yan ³ Wei Ding ^1,4*

• ¹ College of Plant Protection, Southwest University, Chongqing, China
• ² College of Agronomy and Biotechnology, Southwest University, Chongqing, China
• ³ Yibin Tobacco Company of Sichuan Province, Sichuan, China
• ⁴ Southwest University, Chongqing, China

Plants will display a typical dehydration and wilting symptoms after Ralstonia solanacearum infection. Many studies have shown that Abscisic acid (ABA) has been implicated in the wilting, but the role of ABA after R. solanacearum infection remains largely unexplored. ‌The plant water potential and endogenous ABA content of tobacco plants were investigated after R. solanacearum infection, and we assessed the preliminary mechanisms and control effect of exogenous ABA on tobacco bacterial wilt. Here, we show that R. solanacearum can reduce leaf water content (LWC) and leaf water potential (Ψleaf), and promote accumulation of ABA on leave. Notably, foliar spraying 0.78 mg/L ABA could alleviate the wilting by increasing Ψleaf, decreasing stomatal size, stomatal conductance (Gs) and transpiration rate (Tr). 0.78 mg/L ABA application promoted plant growth, reduced the colonization of R. solanacearum, increased the activities of defense enzymes, upregulated the expression of JA/ET-related and ROS-related genes, and suppressed the expression of SA-related gene. Moreover, 0.78 mg/L ABA could reduce the incidence of tobacco bacterial wilt, the control efficiency reaching up to 54.94% at 11 dpi, significantly higher than that of benzothiazole (BTH) with 19.33%. Our findings provided a new result for exogenous ABA controlling tobacco bacterial wilt by reducing water loss and enhancing plant resistance.