Berberine as a promising natural compound to control Penicillium italicum causing blue mold of citrus fruit

Abstract

The blue mold caused by Penicillium italicum is one of the most common diseases in citrus fruit. Berberine from Chinese herb has predominate bioactive effects. This study investigated the inhibitory effect of berberine on P. italicum and the underlying mechanisms. Results showed that berberine displayed excellent efficacy to inhibit mycelial growth and spore germination of P. italicum in vitro dose-dependently. Moreover, berberine damaged the plasma membrane integrity, indicated by increased relative conductivity but decreased contents of soluble protein and reducing sugar of P. italicum mycelia. Meanwhile, higher H2O2 content was also observed in berberine-treated P. italicum mycelia. Additionally, berberine suppressed the disease development in citrus fruit through increasing the enzymatic activities of polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), and chitinase (CHI) as well as contents of total phenols and flavonoids in citrus peel. Furthermore, gene expression analysis suggested that genes encoding these defense-related enzymes were up-regulated by berberine. These results suggested that berberine could be expected as a new natural strategy to control postharvest diseases of citrus fruit.