Tea leaf spot, caused by the fungal phytopathogen Didymella segeticola, is an important foliar disease that can cause huge losses in the production and quality of tea, and there are no effective management measures to control the disease. This study screened a natural antimicrobial chemical for its activity against D. segeticola and studied its mode of action. Antifungal activity of the Streptomyces-derived antimicrobial zhongshengmycin (ZSM) against D. segeticola strain GZSQ-4 was assayed in vitro via the mycelial growth rate method. Optical microscopy and scanning and transmission electron microscopy were used to observe the morphological effects on hyphae treated with ZSM, with these studies complemented by transcriptomic, proteomic, and bioinformatic studies to identify the differentially expressed genes or differentially expressed proteins in hyphae treated with ZSM. Correlation analysis of transcriptomic and proteomic data were used to reveal the mode of action. The results indicated that ZSM could inhibit the growth of hyphae in vitro with a half-maximal effective concentration of 5.9 μg/ml, inducing some morphological changes in organelles, septa, and extracellular polysaccharides, targeting ribosomes to disturb translation, affecting the biosynthesis of some hyphal proteins at the messenger RNA and protein levels, and revealing correlations between findings from transcriptomes and proteomes.
Keywords: Didymella segeticola; action mechanism; antifungi activity; bioinformatics; proteome; tea leaf spot; transcriptome; zhongshengmycin.