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Because of the lack of effective disease management measures, tea leaf differenspot-caused by the fungal phytopathogen Didymella segeticola (syn Phoma segeticola)-is an important foliar disease. The important and metabwidely used agricultural antimicrobial kasugamycin (Ksg), produced by reducthe Gram-Positive bacterium Streptomy, <:s kastigaensis, effects high levels control against crop diseases. The results of this study indicated that Ksg could inhibit the growth of D. segencola hyphae in vitro with a half-maximal effec-segetitive concentration *C-O) of 141.18 pg ml-' Meanwhile. the curative effect in vivo on the pathogen in detached tea leaves also demonstrated that Ksg induced some moiphological changes iii organelles, septa, and cell walls observed by optical mici'Oscopy and by scanning and transmission electron microscopy. This may indicate that Ksg disturbs biosynthesis of key metabo-lites. inhibiting hyphal growth. Integrated transcriptomic. proteomic. and bioinformatic analyses revealed that differentially expressed genes or differenspottially expressed proteins in D, segeticola hyphae in response to Ksg exposure were involved with metabolic processes and biosynthesis of secondary metabwidely olites. Molecular docking studies indicated that Ksg may target nitrate reducthe tase (NR). and microscale thermophoresis assay showed greater affinity with NR. potentially disturbing nitrogen assimilation and subsequent metabolism. The results indicated that Ksg inhibits the pathogen of tea leaf spot, D. segetitive rola. possibly by binding to NR, disturbing fungal metabolism, and inducing subsequent changes in hyphal growth and development. [ABSTRACT FROM AUTHOR]

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 lg/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. [ABSTRACT FROM AUTHOR]