Abstract: 【Objective】The objective of this study is to identify antagonistic strains A316 and A10 obtained from rhizospheric soil of Chinese cabbage, roots of Ormosia yaanensis respectively which have higher inhibition on the resting spore germination of P. brassicae and to develop effective biological control measures against clubroot. 【Method】Strains A316 and A10 were identified by morphological and cultural traits, physio-biochemical characteristics and 16S rDNA sequence analysis. The control efficiency of A316 and A10 against clubroot of Chinese cabbage in a pot experiment and a field plot experiment were evaluated. 【Result】Based on the 16S rDNA sequence analysis, strain A316 was most closely related to Streptomyces griseoruber NBRC 12873 (99.9% similarity). The morphological and cultural traits, and physio-biochemical characteristics of strain A316 conformed with S. griseoruber. While the genetic relationships of strain A10 with many related sequences from GenBank database were closely related. According to morphological and cultural traits, and physio-biochemical characteristics, A10 was affiliated to Griseofuscus of Streptomyces. The control efficiency against clubroot of Chinese cabbage of A316 and A10 were 72.8%, 67.2% in a pot experiment and 68.5%, 56.7% in a field plot experiment. Yield increase per unit area of Chinese cabbage resulted from A316 and A10 were 96.1%, and 64.9%. 【Conclusion】Strain A316 was preliminarily identified as S. griseoruber. Strain A10 was affiliated to Griseofuscus of Streptomyces. A316 and A10 were approved to be promising biocontrol agents for P. brassicae. A316 had better control efficiency against clubroot of Chinese cabbage than A10.

Key words: Plasmodiophora brassicae, antagonistic actinomycetes, Streptomyces griseoruber, Chinese cabbage, clubroot, biological control