The screening and identification of the biological control fungi Chaetomium spp. against wheat common root rot.

Bipolaris sorokiniana is a soil-borne fungal pathogen causing common root rot in wheat, and is difficult to control through chemical and agricultural means. Chaetomium spp. have been documented as potential biological control agents for plant diseases. In this study, seven Chaetomium strains were screened for their abilities to control B. sorokiniana on agar plates. Strain 22-10 significantly inhibited the growth of B. sorokiniana on potato dextrose agar plates, up to 66.7%. Its filtrate of liquid culture also inhibited the mycelial growth of B. sorokiniana, indicating that strain 22-10 produced secondary metabolites against B. sorokiniana. The incidence and disease indexes of common root rot significantly decreased in wheat after treatment with the crude extract of strain 22-10. Six active compounds were purified from crude extract of this fungus culture against B. sorokiniana. Chaetoviridin A showed the highest efficiency to inhibit the growth of B. sorokiniana. Strain 22-10 was identified as Chaetomium globosum based on phylogenetic analysis of the rDNA internal transcribed spacer region and microscopic characteristics. The high control efficiency of strain 22-10 of C. globosum against B. sorokiniana suggested it has potential to be a biocontrol agent for B. sorokiniana.