Investigating the effect of methyl jasmonate on the biocontrol activity of Meyerozyma guilliermondii against blue mold decay of apples and the possible mechanisms involved

Apple is one of the largely grown fruits in China, and it suffers great economic losses caused by Penicillium expansum infection every year. In the present study, we ascertained the efficacy of Meyerozyma guilliermondii enhanced by 200 μmol/L methyl jasmonate (MeJA) in controlling the postharvest blue mold decay of apples and the possible mechanisms involved. The results demonstrated that the biological control ability of M. guilliermondii induced by MeJA in restraining P. expansum infection in apples. The efficacy of M. guilliermondii induced by MeJA significantly decreased the decay incidence and lesion diameter of apples. When treated with M. guilliermondii induced by MeJA, the decay incidence of apples was only 21.6%, while apples treated with M. guilliermondii was 42.4%. M. guilliermondii induced by MeJA also reduced the germ tube length, spore germination rate of P. expansum in PDB and colony diameter of P. expansum in PDA. The results also showed that antagonistic yeast induced by MeJA proliferated better in apple wounds and surface at 4 °C or 20 °C. Meanwhile, the activities of resistance-related peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), Catalase (CAT), and the antibacterial substances of flavonoid contents, total phenolic content were all increased. The results manifested that M. guilliermondii induced by MeJA increased the expression levels of defense-related enzymes in apples. •M. guilliermondii induced by MeJA decreased blue mold decay of apples.•M. guilliermondii induced by MeJA colonized in apples steadily at 20 °C and 4 °C.•M. guilliermondii induced by MeJA decreased spore germination rate of P. expansum.•M. guilliermondii induced by MeJA increased PPO, POD, CAT, PAL activities of apples.•M. guilliermondii induced by MeJA increased the expression of PPO, POD, PAL, CAT.