Discovery of Potential Rosin-Based Triazole Antifungal Candidates to Control <i>Valsa mali</i> for Sustainable Crop Protection
Renle Xu, Han Xu, Yuhang Lou, Meiyue Chang, Yue Kong, Shihao Gu, Yanqing Gao, Shibin Shang, Zhanqian Song, Jie Song, Jian Li
Abstract
To investigate the potential application value of dehydroabietic acid, 27 novel dehydroabietyl-1,2,4-triazole-5-thioether-based derivatives were designed and characterized by IR, 1 H NMR, 13 C NMR, and LC-MS. Their antifungal activities were evaluated against five plant fungi, namely, Valsa mali, Colletotrichum orbiculare, Fusarium graminearum, Sclerotinia sclerotiorum, and Gaeumannomyces graminis; the results showed that compound 5h-1 ( Co. 5h-1 ) exhibited a considerable inhibitory effect against V. mali . Moreover, in vivo experiments indicated that Co. 5h-1 had a certain protective effect on apple branches. The preliminary structure–activity relationship analysis suggested that the electron-withdrawing group on the benzyl group was significantly better than that of other substituent derivatives. Through electron microscopy analysis, it was found that Co. 5h-1 hindered the growth of mycelia, damaged their cell structure, and caused the large accumulation of reactive oxygen species (ROS). Preliminary research on the mode of action indicated that Co. 5h-1 could affect the activity of CAT by increasing the α-helix (0.790%), decreasing the β-sheet (0.170%), which led to the accumulation of ROS. In addition, Co. 5h-1 also affected the activity of CYP51, hindered the biosynthesis of ergosterol, and increased cell membrane permeability. Overall, this above research proposed that Co. 5h-1 can be a novel leading structure for development of a fungicide agent.