Natural compound berberine inhibits apple ring rot fungus Botryosphaeria dothidea

Apple ring rot is a disease caused by Botryosphaeria dothidea that severely reduces apple yield. Currently, management of this disease relies primarily on chemical fungicides. However, chemical fungicides cause fruit contamination. Here we report that berberine, an alkaloid extracted from medicinal plant Coptis chinensis, can efficiently inhibit the B. dothidea isolates collected from different regions in China. The 50% effective concentration (EC50) and minimum inhibitory concentration (MIC) of berberine for B. dothidea were 8.4 similar to 9.8 mu g mL(-1) and 17.1 similar to 20 mu g mL(-1), respectively. Scanning electronic microscope showed efficient inhibition of berberine against the hyphal growth of B. dothidea. Conductivity analysis revealed that berberine increased the membrane permeability of B. dothidea. Remarkably, berberine repressed the activities of succinate dehydrogenase and malate dehydrogenase, two enzymes participating in energy metabolism. In vitro experiments revealed strong inhibition of berberine against the B. dothidea on detached fruits. Field trials showed 78.27% inhibition rate of berberine toward B. dothidea. Collectively, berberine is a promising natural fungicide to control apple ring rot because of its high efficacy, low cost, and safety to human health.