Butylated hydroxyanisole controls anthracnose on postharvest citrus fruit by inducing autophagosome formation in Colletotrichum gloeosporioides

Citrus anthracnose, caused by Colletotrichum gloeosporioides, is a preharvest and postharvest disease that results in economic losses by affecting citrus fruit quality, shelf life, and market value. To date, research on environmental safety, high efficiency and viable alternatives has not been reported. In this study, butylated hydroxyanisole (BHA) was screened and verified to inhibit C. gloeosporioides of citrus. The results showed that BHA could completely inhibit mycelial growth in vitro (0.25 g/L) and absolutely lose its virulence in vivo (20 x Minimum fungicidal concentration (MFC) = 5 g/L). Furthermore, some transparent irregularly shaped vacuolar structures in the cytosol of the BHA-treated conidia were detected by Transmission Electron Microscope (TEM), and autophagosome formation was verified by monodansylcadaverine(MDC) staining. In addition, staining experiments indicated that BHA induced the accumulation of excessive reactive oxygen species (ROS, the DCFH-DA staining rates of C. gloeosporioides conidia treated with 1/2 x MIC and MIC were 26.4% and 83%, respectively), which implied that BHA destroyed spore organelles and damaged cell membrane integrity (the electrical conductivity of conidia treated with 1/2 x Minimum inhibitory concentration (MIC), MIC and MFC was 48.37%, 64.79% and 97.95%, respectively), further resulting in reduced pathogenicity and virulence. In summary, this study provides evidence that BHA has the potential to be a valuable alternative for controlling citrus anthracnose in the future.