Autoclaved yeast enhances the resistance against Penicillium expansum in postharvest pear fruit and its possible mechanisms of action

The study investigated the effect of autoclaved yeast on the control of blue mold in pear fruit and the possible mechanisms involved. The results demonstrated that autoclaved yeast Rhodosporidium paludigenum could stimulate remarkable resistance to the blue mold caused by Penicillium expansum in pear fruit. Autoclaved yeast had no direct antifungal activity against P. expansum in vitro and in vivo while it reduced germination of P. expansum in fruit wounds after 24 h of treatment. Moreover, the activities of four defense-related enzymes (including superoxide dismutase, catalase, peroxidase and phenylalanine ammonia-lyase) and the four pathogenesis-related protein genes (including PR1-like, endoglucanase9, endochitinase-like and PR4) were significantly enhanced and the lipid peroxidation was highly inhibited in the treatment with autoclaved yeast, which was closely related to the mechanism by which autoclaved yeast reduce the blue mold rot in pear fruit. The results from this study provides the basis for further research on the antagonistic mechanism of biocontrol yeasts in induced resistance of harvested fruit.