Evaluation of the antagonistic effect of Streptomyces albidoflavus against Ascochyta onobrychis

Ascochyta onobrychis is the causal pathogenic microorganism of sainfoin leaf spot and black stem, which is a serious disease. A strain of microorganism that has strong antagonistic activity against A. onobrychis was obtained when the pathogen was isolated. To evaluate the exploitation and foreground of the antagonistic microorganism, the present study identified the taxonomic position of the strain by morphological, molecular, and biochemical methods, as well as determined the inhibitory effect of the strain against A. onobrychis. Based on its morphological characteristics, both physiological and biochemical, together with 16S rDNA sequence analysis, the strain was identified as Streptomyces albidoflavus. The colonies ware yellowish white in color on Gause’s agar and produced yellowish white water-soluble pigments and a mycelium hook-like top spiral. The relative inhibition rate to the pathogen was 74.33% that was measured with the dural culture method. The actinomycetes sterile fermentation broth had a strong effect on mycelial growth and spore germination, with inhibitory rates of 80.95% and 93.87%, respectively. The results showed that the actinomycetes had potential value in the biological control of A. onobrychis.