摘要
The litchi downy blight disease of litchi caused byPeronophythora litchiiaccounts for severe losses in the field and during storage. While ample quantitative studies have shown that 6-pentyl-2H-pyran-2-one (6PP) possesses antifungal activities against multiple plant pathogenic fungi, the regulatory mechanisms of 6PP-mediated inhibition of fungal pathogenesis and growth are still unknown. Here, we investigated the potential molecular targets of 6PP in the phytopathogenic oomycetesP. litchiithrough integrated deployment of RNA-sequencing, functional genetics, and biochemical techniques to investigate the regulatory effects of 6PP againstP. litchii. Previously we demonstrated that 6PP exerted significant oomyticidal activities. Also, comparative transcriptomic evaluation ofP. litchiistrains treated with 6PP Revealed significant up-regulations in the expression profile of TOR pathway-related genes, includingPlCytochrome Cand the transcription factorsPlYY1. We also noticed that 6PP treatment down-regulated putative negative regulatory genes of the TOR pathway, includingPlSpm1andPlrhoH12inP. litchii. Protein-ligand binding analyses revealed stable affinities between PlYY1, PlCytochrome C, PlSpm1, PlrhoH12 proteins, and the 6PP ligand. Phenotypic characterization ofPlYY1targeted gene deletion strains generated in this study using CRISPR/Cas9 and homologous recombination strategies significantly reduced the vegetative growth, sporangium, encystment, zoospore release, and pathogenicity ofP. litchii. These findings suggest that 6PP-mediated activation ofPlYY1expression positively regulates TOR-related responses and significantly influences vegetative growth and the virulence ofP. litchii. The current investigations revealed novel targets for 6PP and underscored the potential of deploying 6PP in developing management strategies for controlling the litchi downy blight pathogen.Keywords:P. litchii;6-pentyl-2H-pyran-2-one (6PP);TOR pathway;CRISPR/Cas 9;PlYY1
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