Shu Xu1,2, Xingzeng Zhao1,2, Fei Liu1,2, Yan Cao1,2,3, Bi Wang1,2, Xiangyun Wang1,2, Min Yin1,2, Qizhi Wang1,2, Xu Feng1,2. 1. Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China. 2. The Jiangsu Provincial Platform for Conservation and Utilization of Agricultural Germplasm, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China. 3. College of Life Sciences, Nanjing Agricultural University, Nanjing, China.
Abstract
BACKGROUND: Xanthomonas oryzae pv. oryzae (Xoo) causes rice bacterial blight, which is one of the most devastating diseases on rice. Parthenolide (PTL) is a sesquiterpene lactone possessing multiple bioactivities. In the preliminary study, we found PTL can totally inhibit the growth of Xoo at 10 mg L-1 in vitro. In this study, we aim to further evaluate the anti-bacterial activity of PTL against Xoo and discern the role of oxidative stress in its bactericidal effect. RESULTS: PTL was effective against Xoo both in vitro and in vivo. PTL induced reactive oxygen species (ROS) accumulation in Xoo, leading to cell death, while exogenous catalase can fully abolish its bactericidal effect. PTL sensitivity of catalase deletion mutants of Xoo increased significantly compared with that of wild-type Xoo strain. In addition, PTL treatment increased glutathione peroxidase activity and decreased glutathione (GSH) reductase activity in Xoo, but had no effect on its catalase and superoxide dismutase activities. Interestingly, PTL dramatically reduced the GSH level in Xoo, resulting in disturbed GSH/GSSG balance. Moreover, PTL rapidly reacted with GSH by a nucleophilic addition reaction. CONCLUSION: PTL is a promising lead compound for developing bactericide against Xoo. PTL rapidly reacts with GSH, resulting in disturbed GSH/GSSG balance in Xoo, which causes ROS accumulation, leading to cell death. Oxidative stress plays a critical role in the bactericidal effect of PTL against Xoo.
BACKGROUND:Xanthomonas oryzae pv. oryzae (Xoo) causes rice bacterial blight, which is one of the most devastating diseases on rice. Parthenolide (PTL) is a sesquiterpene lactone possessing multiple bioactivities. In the preliminary study, we found PTL can totally inhibit the growth of Xoo at 10 mg L-1 in vitro. In this study, we aim to further evaluate the anti-bacterial activity of PTL against Xoo and discern the role of oxidative stress in its bactericidal effect. RESULTS:PTL was effective against Xoo both in vitro and in vivo. PTL induced reactive oxygen species (ROS) accumulation in Xoo, leading to cell death, while exogenous catalase can fully abolish its bactericidal effect. PTL sensitivity of catalase deletion mutants of Xoo increased significantly compared with that of wild-type Xoo strain. In addition, PTL treatment increased glutathione peroxidase activity and decreased glutathione (GSH) reductase activity in Xoo, but had no effect on its catalase and superoxide dismutase activities. Interestingly, PTL dramatically reduced the GSH level in Xoo, resulting in disturbed GSH/GSSG balance. Moreover, PTL rapidly reacted with GSH by a nucleophilic addition reaction. CONCLUSION:PTL is a promising lead compound for developing bactericide against Xoo. PTL rapidly reacts with GSH, resulting in disturbed GSH/GSSG balance in Xoo, which causes ROS accumulation, leading to cell death. Oxidative stress plays a critical role in the bactericidal effect of PTL against Xoo.