Abstract:

Strain L-30，with effective inhibitory activity against Botrytis cinerea and 10 other postharvest fruit diseases，was selected from rhizosphere of pear orchard by dual-culture method. The morphological characters and 16S rDNA sequence analysis were used to identify the selected strain. The mechanisms involved in the biocontrol process of strain L-30 against B. cinerea were also investigated. Results showed that the control efficacy of strain L-30 against pear gray mold reached 40% on ‘Huangguan’pears. Based on morphological characters and 16S rDNA sequence analysis，L-30 was identified as Streptomyces polychromogenes. The supernatant of strain L-30’s fermentation could effectively reduce the germination of B. cinerea spores，the inhibitory efficiency of its 100-fold dilution reached 50.14%. In addition，S. polychromogenes L-30 could significantly induce the resistance of‘Huangguan’pear against pear gray mold，and also increase the activities of peroxidase（POD），superoxide dismutase（SOD），catalase（CAT）and phenylalanine ammonia lyase（PAL）.

Key words: pear, gray mold, Streptomyces, biological control, induced resistance, defense-related enzymes