Streptomyces rochei A 1 induces resistance and defense related responses against Botryosphaeria dothidea in apple fruit during storage
Abstract Apple ring rot caused by Botryosphaeria dothidea is an important disease in most apple growing regions in China. It results in severe losses during fruit storage. Induced resistance against plant pathogens is a promising alternative to traditional control strategies. In the present study, a potential biocontrol agent, Streptomyces rochei A 1, was evaluated for its induction of resistance against B. dothidea in postharvest apple fruit, and the defense mechanisms involved were investigated. The results indicated that S. rochei A 1 treatment could effectively induce the resistance of apple fruit to ring rot caused by B. dothidea The lesion area and disease incidence were 65.4% and 27.1% lower than those of the control fruit after storage at 25 degC for 7 d. S. rochei A 1 treatment significantly increased the activities of peroxidase (POD) superoxide dismutase (SOD) catalase (CAT) and phenylalanine ammonia lyase (PAL) and highly inhibited lipid peroxidation. b 1,3 glucanase and chitinase activities and H 2 O 2 generation were also markedly promoted by the biocontrol agent. Moreover, the expression levels of three pathogenesis related proteins genes PR 8 GLU and CHI were enhanced. The most significant increase was observed in apple fruit pretreated with S. rochei A 1 and inoculated with B. dothidea Therefore, our results suggest that S. rochei A 1 treatment induces resistance against B. dothidea in apple fruit by stimulating a series of defense responses.