The inhibitory effect of tavaborole on the invasion of Botrytis cinerea in grapes and tomatoes, as well as the potential mechanism involved, was discovered in this study. Our findings showed that tavaborole inhibited Botrytis cinerea spore germination and mycelial expansion in vitro and that the control efficiency in vivo on fruit decay was dose-dependent, which was effective in reducing disease severity and maintaining the organoleptic quality of the fruit, such as reducing weight loss and retaining fruit hardness and titratable acid contents during storage. Furthermore, the precise mechanism of action was investigated further. Propidium iodide staining revealed that Botrytis cinerea treated with tavaborole lost membrane integrity. For further validation, cytoplasmic malondialdehyde accumulation and leakage of cytoplasmic constituents were determined. Notably, the inhibitory effect was also dependent on inhibiting the activities of aminoacyl-tRNA synthetases involved in the aminoacyl-tRNA biosynthesis pathway in Botrytis cinerea. The above findings concluded that tavaborole was effective against Botrytis cinerea infection in postharvest fruit, and a related mechanism was also discussed, which may provide references for the drug repurposing of tavaborole as a postharvest fungicide.

BACKGROUND: The resistance of traditional chemical fungicides to plant pathogenic fungi and the threats to the safety of humans and the environment highlight an urgent need to find safe and efficient alternatives to chemical fungicides. Owing to the wide spectrum of antifungal activities, low persistence and nontoxicity to mammals and aquatic life, essential oils have considerable potential as low-risk pesticides. In this study, the essential oil and the main components of Angelica sinensis (Oliv.) Diels (Danggui) were extracted, analyzed by GC-MS, and evaluated for their antifungal activities against six plant pathogenic fungi.RESULTS: 3-butylidenephthalide (3-BPH) showed the best antifungal activity against Fusarium graminearum with an EC 50 value of 14.35 ∼g mL −1 . The antifungal mechanistic studies revealed that 3-BPH induced the generation of endogenous ROS to cause lipid peroxidation of the cell membrane and inhibited the biosynthesis of ergosterol, thereby causing the cell membrane damaged to exert its fungicidal activity. Significantly, 3-BPH could reduce deoxynivalenol production compared to the control.CONCLUSION: This study demonstrated the potent fungicidal activity of natural phthalide compound 3-BPH and highlighted its potential as an alternative agent to control F. graminearum.

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Phytopathogenic bacteria are a major cause of crop mortality and yield reduction, especially in field cultivation. The lack of effective chemistry agri-bactericides is responsible for challenging field prevention and treatment, prompting the development of long-lasting solutions to prevent, reduce, or manage some of the most devastating plant diseases facing modern agriculture today and in the future. Therefore, there is an urgent need to find lead drugs preventing and treating phytopathogenic bacterial infection. Drug repurposing, a strategy used to identify novel uses for existing approved drugs outside of their original indication, takes less time and investment than Traditional R&D Strategies in the process of drug development. Based on this method, we conduct a screen of 700 chemically diverse and potentially safe drugs against Xanthomonas oryzae PV . oryzae ACCC 11602 ( Xoo ), Xanthomonas axonopodis PV . citri ( Xac ), and Pectobacterium atrosepticum ACCC 19901 ( Pa ). Furthermore, the structure-activity relationship and structural similarity analysis of active drugs classify potent agri-bactericides into 8 lead series: salicylanilides, cationic nitrogen-containing drugs, azole antifungals, N -containing group, hydroxyquinolines, piperazine, kinase inhibitor and miscellaneous groups. MIC values were evaluated as antibacterial activities in this study. Identifying highly active lead compounds from the screening of approved drugs and comparison with the currently applied plant pathogenic bactericide to validate the bactericidal activity of the best candidates and assess if selected molecules or scaffolds lead to develop new antibacterial agents in the future. In conclusion, this study provides a possibility for the development of potent and highly selective agri-bactericides leads.

Background The unreasonable use of chemical fungicides causes common adverse consequences that not only affect the environment, but also cause resistance and resurgence problems of plant pathogens, which are extremely harmful to human health, the economy, and the environment. Based on the rich biological activities of boron‐based compounds, 82 phenylboronic acid derivatives were selected and their antifungal activities against six agricultural plant pathogens were determined. Combined with transcriptomics tools, the mechanism of action of compound A49 (2‐chloro‐5‐trifluoromethoxybenzeneboronic acid) against Botrytis cinerea Pers (B. cinerea) was studied. Results The EC50 values of compounds A24, A25, A30, A31, A36, A41, A49 and B23 against all six fungi were under 10 μg/mL. Compound A49 displayed significant activity against B. cinerea (EC50 = 0.39 μg/mL), which was better than that of commercial fungicide boscalid (EC50 = 0.55 μg/mL). A49 not only inhibited the germination of B. cinerea spores, but also caused abnormal cell morphology, loss of cell membrane integrity, enhanced cell membrane permeability, and accumulation of intracellular reactive oxygen species. Further findings showed that A49 reduced cellular antioxidant activity, and peroxidase and catalase activities. Transcriptomic results indicated that A49 could degrade intracellular redox processes and alter the metabolism of some amino acids. Meanwhile, A49 showed obvious activity in vivo and low cytotoxicity to mammal cells. Conclusion The boron‐containing small molecule compounds had high efficiency and broad‐spectrum antifungal activities against six plant pathogens, and are expected to be candidate compounds for a new class of antifungal drugs. © 2023 Society of Chemical Industry.