Biological Control of Gray Mold and Induction of Defense Responses in Sweet Cherry (Prunus avium L. cv. Takdaneh Mashhad) by Bacillus Subtilis and Oregano Essential Oil

Gray mold is one of the most important pathogens of cherry fruit. In the present study, the ability of bioinhibition of Botrytis cinerea by antagonist bacteria and the effects of adding marjoram essential oil  on the growth of pathogenic fungi was evaluated. According to the results, with increasing in the concentration of essential oil, the growth rate of fungi decreased. In vivo, cherry fruits were infected with a suspension of 105 hg/ml of pathogenic fungus, then separately treated with a suspension of 108 cells/ml of selected strains of antagonist bacteria and marjoram essential oil at 5 levels. The qualitative parameters were examined at three times of zero, 15 and 30 days. The results showed that the treatment of Bacillus bacterium and marjoram essential oil at a concentration of 750 μl/l were the most effective treatment to increase the level of antioxidant activity and phenylalanine-ammonialyase enzyme activity. Total phenol content and anthocyanin content at the concentration of 1000 μl/l  were the highest after 30 days. The highest amount of polyphenol oxidase enzyme was recorded after 15 days at the concentration of 750 μl/l. According to the results of this study, the mechanism of B. subtilis and marjoram essential oil in the control of gray mold of cherries is probably due to the induction of resistance in cherry fruit and increased antioxidant activity.