Trichothecium roseum is a major postharvest pathogenic fungus, which can infect apple, muskmelon, tomato and other fruit and vegetables, resulting in postharvest diseases. T. roseum infection not only leads to considerable economic losses, but also accumulates mycotoxins, posing a threat to human's health. Phospholipase D (PLD), as an important phospholipid hydrolase, accelerating the infection of pathogens by damaging the structure of the cell membrane. Therefore, PLD plays a crucial role during pathogen-host interactions. In this study the effect of 1-butanol (a PLD specific inhibitor) treatment on the growth of T. roseum and the pathogenicity on muskmelon fruit was evaluated in this study. T. roseum was treated with PLD inhibitor 1-butanol at concentrations of 0.125%, 0.25%, 0.5% and 1.0%. Spore germination, germ tube length, hyphal growth, colony diameter, sporulation, conidial morphology were assessed in vitro. The pathogenicity of T. roseum on muskmelon fruit, as well as the genes expression and activity of PLD were determined during T. roseum infection of muskmelon. The results indicated that 0.5% 1-butanol significantly inhibited spore germination, germ tube length, hyphal growth, and sporulation of T. roseum.. Moreover, 1-butanol treatment significantly suppressed lesion expansion of inoculated muskmelon fruit, when compared with the control group, the PLD activity was reduced in fruits treated with 0.5% 1-butanol. TrPLD gene expression analysis suggested that there are four family genes of TrPLD1, TrPLD2, TrPLD3, and TrPLD4, the four TrPLDs were significantly down-regulated after 0.5% 1-butanol application, among which, TrPLD3 played a more crucial role than the other three genes. The results suggested that specific inhibitor 1-butanol treatment decreased the pathogenicity of T. roseum on muskmelon fruit by suppressing the growth of T. roseum, and down-regulating TrPLD gene expression and reducing the activity of PLD.
