Efficacy of Meyerozyma caribbica in the biocontrol of blue mold in kiwifruit and mechanisms involved

• M. caribbica had a great biocontrol efficacy against blue mold decay of kiwifruit. • M. caribbica could inhibit the growth of Penicillium expansum in vitro. • M. caribbica induced PPO, POD, APX, SOD and PAL activities of kiwifruit. • M. caribbica increased flavonoids, phenolic and lignin content of kiwifruit. Kiwifruit are susceptible to Penicillium expansum infestation, resulting in decay and causing severe economic losses. In this study, we investigated the efficacy and related mechanism of Meyerozyma caribbica in controlling and preventing of P. expansum . The yeast was found to significantly reduce the disease incidence of blue mold in kiwifruit, inhibit the growth of P. expansum in vitro , and reduce both the spore germination rate and germ tube length in a dose-dependent manner. Meanwhile, M. caribbica can stably growth on kiwifruit at 20℃ and 4℃ and had the ability to form biofilm. In addition, the results of this study also showed that M. caribbica induced an increase in polyphenol oxidase (PPO), peroxidase (POD), ascorbate peroxidase (APX), superoxide dismutase (SOD), and phenylalanine ammonia lyase (PAL) activities of kiwifruit and reduced the content of malondialdehyde (MDA). The content of secondary metabolites such as total phenols, flavonoids, and lignin were also increased after yeast application. These experiments indicate that M. caribbica has a strong adaptation to the environment and relies on competition for nutrients and space against pathogens. The induction of disease resistance in fruits is also one of the important mechanisms to control the occurrence of blue mold in kiwifruit. In summary, M. caribbica has the potential to be an antagonistic yeast for controlling postharvest blue mold of kiwifruit.