Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/7/2011
Publication Date: 4/11/2011
Citation: Wisniewski, M.E., Liu, J., Macarisin, D., Droby, S., Hershkovitz, V. 2011. Suppressive-subtractive cDNA analysis indicates that elevated yeast antioxidant gene expression is associated with increased stress tolerance and biocontrol efficacy in the antagonistic yeast, Candida Oleophila [abstract]. International Congress Postharvest Pathology, Lleida, Spain, p. 109. Interpretive Summary:
Technical Abstract: Several yeast species have been used as biocontrol agents against postharvest diseases of fruits and vegetables. The objectives of the current study are to develop a better understanding of the role of reactive oxygen species (ROS) in relation to viability and biocontrol activity of Candida oleophila, and to develop strategies to improve the efficacy of yeast biocontrol agents. Previously, we demonstrated that a mild heat shock (HS) pretreatment could improve the tolerance of Metschnikowia fructicola to subsequent high temperature and oxidative stress, and also improve biocontrol activity against Penicillium expansum on apple fruit (Liu et al. 2011). Additionally, we found that pre-exposure of yeast cells to a solution of 1.0 mM glycine betaine enhanced the tolerance of Cystofilobasidium infirmominiatum to oxidative stress and also improved biocontrol efficacy (In Review). In the present study, a mild oxidative stress pretreatment (30 min at 5.0 mM H2O2) improved the tolerance of C. oleophila to heat and oxidative stresses, and its biocontrol efficacy. Suppression subtractive cDNA hybridization (SSH) analysis was used to identify gene expression in yeast exposed to sub-lethal oxidative stress compared to untreated controls. Levels of gene expression were confirmed using semi-quantitative PCR. Data indicated that antioxidant genes, such as Catalase, Glutathione oxidoreductase, and Glutathione peroxidase/redox transducer, were upregulated. The elevated expression of these genes contributed to less ROS accumulation and a lower level of protein oxidation under heat and oxidative stresses. Moreover, the stress-adapted yeast showed higher growth rate in YPD with pH 4 and in apple fruit. Collectively, results indicate oxidative stress adaptation contributed to improvement in stress tolerance and biocontrol efficacy of C. oleophila by a mechanism that involves the activation of antioxidant gene expression in yeast.