Pantoea vagans strain BWL1 controls blue mold in mandarin fruit by inhibiting ergosterol biosynthesis in Penicillium expansum

Abstract

Penicillium expansum is a major postharvest fungal pathogen of a variety of fruits. Recently, Pen. expansum has been reported to infect citrus fruit; however, the management of Pen. expansum on citrus has not been studied. Pantoea vagans strain BWL1 was isolated from the surface of mandarin fruit. Here, its inhibitory effect on postharvest blue mold on mandarin fruit was evaluated. Pan. vagans inhibited conidial germination and mycelial growth of Pen. expansum. Cell-free fermentation extract of Pan. vagans inhibited the expression of ergC, a gene involved in ergosterol biosynthesis, and decreased the ergosterol content in Pen. expansum, resulting in plasma membrane disruption in the fungal pathogen. In vivo experiments showed that the development of blue mold caused by Pen. expansum on citrus fruit was significantly decreased by treatment with Pan. vagans strain BWL1. These results suggest that Pan. vagans can produce metabolites that exhibit antifungal activity toward Pen. expansum by inhibiting the biosynthesis of ergosterol. The application of Pan. vagans strain BWL1 could be effective for the postharvest management of blue mold in citrus fruit.