Taxonomy of antagonistic strain B1 and control effect of tomato gray mould

Xie Chenzhao Yang Yiling Li Lei Li Jinyun Wang Jianhui Wang Huimin (Department of Plant Pathology, China Agricultural University, Beijing 100193, China)

actinomycetes strain B1; tomato gray mould; control tests; Streptomyces lavendulae

In order to confirm the potential appliance of an antagonistic actinomycetes strain B1 for biocontrol of plant diseases, the fungistatic and bacteriostatic activity of this strain was determined by confronting incubation on PDA plates, control tests on detached leaves and fruits in vitro and control on potted plants in greenhouse. The taxonomic identification of the strain was also carried out with multiphase taxonomy. The liquid fermentation medium of strain B1 was screened out by single factor and orthogonal array experiments. Results showed that strain B1 exhibited strong inhibition activity to all 10 plant pathogenic fungi tested and 3 out of 5 plant pathogenic bacteria, especially to Botrytis cinerea, Alternaria solani, Rhizoctonia cerealis, Xanthomonas campestris and Acidovorax avenae. In particular, 86.25% growth inhibition rate on Botrytis cinerea was observed. The secondary metabolites of strain B1 showed teratogenic effect on the mycelia of B.cinerea. The biocontrol effects of strain B1 to gray molds of tomato detached leaves and plants in greenhouse were 68.80% and 64.03%, respectively. Studies on its morphology, physiological and biochemical characteristics and 16S rDNA sequence analysis showed that strain B1 belongs to Streptomyces lavendulae. Liquid fermentation medium for strain B1 was screened out through optimization experiment, as with glucose 15 g, corn slurry 20 g,NH4H2PO4 0.5 g,MgSO4 1.0 g and tap water 1 000 mL, pH 7.2-7.4.