Exposure of Candida oleophila to sublethal salt stress induces an antioxidant response and improves biocontrol efficacy

In the present study, a mild salt stress (1M NaCl, for 30 min) pretreatment of Candida oleophila increased its subsequent tolerance to lethal levels of salt stress (6M NaCl), and low pH (pH 3.4). The sublethal salt stress induced the activation of antioxidant enzymes in the antagonistic yeast, including catalase, thioredoxin reductase, glutathione peroxidase, and glutathione reductase, at both the transcript and enzyme activity level. Sublethal salt stress-adapted (SA) yeast cells exhibited higher survival, compared to non-stress-adapted (NSA) cells, when exposed to 6M NaCl. SA cells exhibited increased efficacy in controlling infection of kiwifruit by Penicillium expansum and Botrytis cinerea, and a higher growth rate in fruit wounds, compared to the NSA yeast. Collectively, the study further supports the premise that stress adaptation of antagonistic yeasts can improve their biocontrol efficacy.