Induction of resistance in apple fruit inoculated with antagonistic Candida membranifecians isolates and Botrytis mali

The biocontrol activity of two isolates of Candida membranifaciens against grey mold of apple fruit caused by Botrytis mali and their ability to induce biochemical defense responses in apple tissue were investigated. Apple fruit (Malus domestica) wounds were inoculated with 50 µl yeast suspension (1 × 107 CFU/ml) of C. membranifaciens followed 4 h later by 20 µl of conidial suspension of B. mali (1 × 105 conidia/ml). The apples were then incubated at 20 ºC for 8 days. Lesion diameter sizes were measured 4 and 8 days after pathogen inoculation. In addition to controlling grey mold، these two isolates of C. membranifaciens caused increases in peroxidase and β-1، 3-glucanase activities. These isolates also caused inhibition in catalase activity. The accumulation of phenolic compounds was increased in apple fruit treated with antagonists and inoculated with B. mali and exhibited the highest level 6 days after treatment. The ability of C. membranifaciens to affect H2O2-metobolizing enzymes and increase levels of β-1، 3-glucanase activity and phenolic compounds may be one of mechanisms responsible for its biocontrol activity.