Biocontrol potential of Streptomyces albidoflavus SC-3 on kiwifruit soft rot caused by Botryosphaeria dothidea

Kiwifruit soft rot is a disease caused by fungal pathogens such as Botryosphaeria dothidea, which considerably restricts the development of kiwifruit industry. To provide novel management strategies against kiwifruit soft rot disease, potential biocontrol actinomycete strains were isolated from kiwifruit rhizosphere soil. A total of 21 actinomycete strains were obtained and strain SC-3 exhibited the highest biocontrol activity against B. dothidea. Based on the morphological, biochemical and molecular characteristics strain SC-3 was identified as Streptomyces albidoflavus. The SC-3 and its aseptic filtrate (AF) exhibited excellent antifungal activities against 11 tested pathogenic fungi. AF displayed antifungal effects through suppressing mycelial growth, spore germination, and the pathogenicity of B. dothidea. Electron microscopy analysis revealed that AF could cause significant alterations on ultrastructure of B. dothidea. Moreover, AF severely damaged cell membrane integrity, resulting in the leakage of cellular components in B. dothidea. Metabolomic analyses of SC-3 AF revealed the presence of several important antifungal compounds in the AF such as antimycin, and candicidin. Correspondingly, the whole genome analyses of SC-3 identified gene clusters responsible for the biosynthesis of these compounds. Overall, SC-3 is a potential biological control agent against B. dothidea and other fungal phytopathogens. •Streptomyces albidoflavus SC-3 exhibited strong antifungal activity against Botryosphaeria dothidea.•Strain SC-3 aseptic filtrate damaged mycelial morphology and the cell integrity of B. dothidea.•Strain SC-3 aseptic filtrate significantly reduced the severity of kiwifruit rot.•Biosynthetic gene clusters were found in the sequencing genome of strain SC-3.•Some secondary metabolites were identified in strain SC-3 aseptic filtrate.