The use of Aloe vera gel coating supplemented with Pichia guilliermondii BCC5389 for enhancement of defense-related gene expression and secondary metabolism in mandarins to prevent postharvest losses from green mold rot

The effect of the antagonistic yeast Pichia guilliermondii, strain BCC5389, mixed in Aloe vera gel (AG) as a coating for postharvest mandarins was investigated. It was found to elicit defense-related gene expression and enzyme activities, as well as bioactive compound accumulation in the flavedo tissues of the fruit. This was led to significantly prevent fruit decay caused by Penicillium digitatum. Substantial levels of gene transcripts associated with plant defense mechanisms such as lipoxygenase, phenylalanine ammonia-lyase, and peroxidase along with enzyme abundances were induced. Accumulation of shikimic acid, total phenolics and lignin were also detected in the treated fruit tissues. None of the fruit quality parameters were affected by the treatments investigated over the storage period. The antagonistic yeast strain BCC5389 mixed with the AG coating agent showed a strong potential to maintain the quality of the fruit. Conclusively, this yeast and AG mixture prevented crop loss caused by green mold during postharvest storage through the induction of the mandarins' natural defense mechanisms.