Volatile organic compounds and rapid proliferation of Candida pseudolambica W16 are modes of action against gray mold in peach fruit

Abstract The effectiveness of Candida pseudolambica W16 as a biocontrol agent against Botrytis cinerea in peach fruit was investigated. The results show that C. pseudolambica W16 significantly reduced the disease incidence of gray mold by 41.2 % on day 3 in peach inoculated with B. cinerea, and repressed natural decay whilst having no negative effects on postharvest quality of non-inoculated fruit. The modes of action investigated were including in vivo growth dynamics, volatile organic compounds (VOCs) effects, parasitism, and biofilm formation. C. pseudolambica W16 rapidly colonized on the fruit surface and within the wounds that are artificially made in peaches; these were determined using growth assays and scanning electronic microscopy, respectively. VOCs emitted from C. pseudolambica W16 inhibited the mycelial growth and conidia germination of B. cinerea, and caused abnormalities in mycelium morphology and ultrastructure. Fourteen VOCs were identified with the main compounds being 3-methyl-1-butanol and 2-phenylethanol, which made up 85.90 % of the relative peak area. C. pseudolambica W16 did not produce detectable amounts of the hydrolytic enzymes chitinase, β-1,3- glucanase, protease, or cellulase. Its ability to form a biofilm was weak. These results indicate that the rapid growth and antifungal VOCs production of C. pseudolambica W16 are the primary modes of action against B. cinerea.