Phytic acid pretreatment potentiates the biocontrol efficacy of Meyerozyma caribbica against Aspergillus carbonarius infection in table grapes: Insights from physiological and transcriptomic analyses

Abstract

Meyerozyma caribbica, previously known as Candida fermentati, is a sporogenous yeast belonging to the Meyerozyma guilliermondii species complex. It is present in various environmental niches owing to its diverse physiological and metabolic capacities that promote adaptation and survival. This study used phytic acid (PA) pretreated M. caribbica to control sour rot caused by Aspergillus carbonarius in grape berries via exploring the physiological and molecular mechanisms involved. Table grapes were treated with either sterile distilled water (SDW) as a control (CK), PA only (E10), M. caribbica alone (Y), or M. caribbica enhanced with PA (YE10) for four days after inducing decay with A. carbonarius. Pretreatment of M. caribbica with 10 µmol/mL of PA significantly reduced the incidence of decay caused by A. carbonarius by 64.11 %, compared to a 25 % reduction by M. caribbica alone, after four days of storage at 20°C. Additionally, M. caribbica pretreatment with 10µmol/mL PA effectively suppressed mycelia growth and spore germination from A. carbonarius both in vitro and in vivo. This treatment boosted the activity of defense-related enzymes like polyphenol oxidase (PPO), chitinase (CHI), phenylalanine ammonia-lyase (PAL), and β-1,3-glucanase (GLU). The gene expression levels of these enzymes were elevated in fruits treated with PA-enhanced M. caribbica. Based on transcriptome analysis, 111 genes were differentially expressed (DEGs), 59 up-regulated and 52 down-regulated, and enriched in pathways associated with antioxidant metabolites implicated in resistance to diseases, the brassinosteroid biosynthetic pathway, and others. This comprehensive method using physiological and transcriptomic techniques to study the management of A. carbonarius rot in table grapes by M. caribbica enhanced with PA may offer an alternative strategy and help manage postharvest diseases of table grapes.