Sour rot caused by Aspergillus carbonarius is a common postharvest disease of grapes, which leads to the declined fruit quality and serious economic losses of grape industry. In this study, we investigated the control effectiveness of Sporidiobolus pararoseus Y16 induced by cyclic adenosine monophosphate (cAMP) against postharvest sour rot of grapes, and explored the potential action mechanisms. The outcomes presented that S. pararoseus Y16 induced by 0.05 mM cAMP for 24 h further mitigated sour rot compared with S. pararoseus Y16 cultured without cAMP. cAMP could enhance the colonization ability of S. pararoseus Y16. More importantly, cAMP-induced yeast further boosted the activities of antioxidant enzymes and the expression level of the corresponding genes, thus improving the ability of scavenging reactive oxygen species of grapes. Moreover, S. pararoseus Y16 induced by cAMP further mounted the activities of defensive enzymes in grapes, as well as the expression level of the corresponding genes, thereby strengthening the disease resistance of grapes. Additionally, the accumulation of resistant secondary metabolites was further augmented, which also contributed to improving the disease resistance of grapes. This research revealed that cAMP-induced culture is helpful to improve the effectiveness of S. pararoseus Y16 in controlling postharvest sour rot of grapes. This research provides a novel and effective biocontrol strategy for the grape industry to mitigate postharvest sour rot. By using cAMP-induced antagonistic microorganisms, the reliance on chemical fungicides could be potentially reduced, thereby promoting sustainable agricultural practices and enhancing the overall quality and safety of grape products.
Aspergillus carbonarius- induced sour rot is an important postharvest disease affecting grapes. Previous study demonstrated that cAMP induction boosts the biocontrol efficiency of Sporidiobolus pararoseus Y16 in combating postharvest sour rot of grapes. Oxidative stress experienced by the antagonistic yeast at fruit wound sites is a key factor limiting its biocontrol efficacy. This research investigated how inducing yeast cells with cAMP effects on tolerance to oxidative stress and explored underlying mechanisms. Results showed that cAMP treatment significantly increased yeast survival rate under exogenous oxidative stress. Physiological analysis revealed a synergistic enhancement on enzyme activities, such as SOD, POD, and CAT in cAMP-induced yeast, accompanied by reduced levels of reactive oxygen species (ROS) under H 2 O 2 stress in vitro and at grape wound sites. Furthermore, levels of protein carbonylation, malondialdehyde (MDA) and trehalose were decreased. Transcriptomic analysis identified upregulation of key genes involved in one-carbon metabolism, thiamine biosynthesis, and amino acid metabolism, such as MTHFR , THI5 , ALDH7A1 , CTH , and proB, which collectively promoted NADPH regeneration, glutathione (GSH) synthesis, aldehyde detoxification, and direct ROS scavenging. In conclusion, cAMP induction activates a multilayered antioxidant defense system in S. pararoseus Y16 through metabolic reprogramming, significantly enhancing its adaptability to the oxidative stress microenvironment of grapes. These findings provide a theoretical basis for optimizing the performance of biocontrol yeasts, demonstrating their significant application prospects.
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