Management of blue mold (Penicillium italicum) on mandarin fruit with a combination of the yeast, Meyerozyma guilliermondii and an alginate oligosaccharide

Abstract The ability of an antagonistic yeast Meyerozyma guilliermondii and an alginate oligosaccharide (AOS), a bio-active compound extracted from brown algae, to control postharvest blue mold and natural infection on mandarin fruit was evaluated. Results indicated that M. guilliermondii and AOS as individual treatments, significantly inhibited blue mold development and natural decay occurrence on mandarin fruit, compared to the untreated, control fruit. The combination of both M. guilliermondii and AOS, however, provided better control than either treatment alone. M. guilliermondii growth in mandarin wounds was not affected by AOS. Further analysis indicated that M. guilliermondii and AOS individually or in combination elevated peroxidase and phenylalanine ammonia-lyase enzyme activity, as well as total phenolics in mandarin fruit. The ability of AOS to improve the biocontrol efficacy of M. guilliermondii may be partially attributed to defense response induction in mandarin fruit. AOS also reduce water loss in mandarin fruit. Collectively, the data indicated that the combined application of M. guilliermondii and AOS represents an effective method of postharvest disease management in citrus fruit.