Abstract:

In order to obtain more antagonists for controlling postharvest strawberry disease, Botrytis cinerea was used as
an indicator strain to screen antagonistic actinomyces out of 78 strains isolated from strawberry rhizosphere. The inhibitory
spectrum of antagonistic strain T3-5 was tested by agar block method, and the effect of its cell-free fermentation filtrate on
postharvest decay and quality of fresh strawberry fruits was assessed. The results showed that strain T3-5 had the strongest
inhibitory effect on B. cinerea and six other selected postharvest pathogens, and the diameter of inhibitory zone against
B. cinerea was 22.5 mm. Based on its morphological characteristics and 16S rDNA sequence, the antagonistic strain T3-5
was primarily identified as Streptomyces xanthophaeus. Its cell-free fermentation filtrate significantly (P < 0.05) decreased
the incidence of strawberry fruit rot. In addition, assays demonstrated that T3-5 filtrate treatment could slow down the decline
of postharvest strawberry fruit firmness, soluble solid content, titration acid content and vitamin C content during storage period.
Conclusively, the antagonistic strain T3-5 has potential value in biological control against strawberry postharvest diseases.

Key words: Botrytis cinerea, Streptomyces xanthophaeus, antagonistic strain, strawberry, storage quality