Screening, identification and biological control effect of antagonistic fungus against fusarium wilt of Saposhnikovia divaricata

Objective  The present study aimed to screen and isolate the antagonistic fungal strains with strong control effect against fusarium wilt from rhizosphere soil ofSaposhnikovia divaricata.

Method  The strain MR-97, which was antagonistic to Fusarium oxysporum, was isolated from the rhizosphere soil of S. divaricata by confrontation culture method, and its bacteriostatic spectrum was determined. The strain was identified by fungal colony characteristics, microscopic characteristics and ITS sequence analysis. The effect of strain MR-97 on hyphae growth of pathogenic fungus were recorded by microscopic examination. The colonization ability of strain MR-97 in the soil was evaluated by antibiotic marker method. The control effect of strain MR-97 on fusarium wilt of S. divaricata were evaluated by pot experiment in the field.

Result  The antagonistic strain MR-97 was screened with antibacterial rate of 64.44% againstF. oxysporum. It also had strong antibacterial effect against eight common pathogens including F. equiseti and Botrytis cinerea, etc. The strain MR-97 was identified asAspergillus terreus. The hyphal of pathogen enlargement, malformation, damage and agglutinated with inclusions, etc. when the strain MR-97 and F. oxysporum were cultured in confrontation. It had a good colonization effect in the soil, and the highest content of soil bacteria was 9.8×10⁶ CFU/g. The biocontrol effect of MR-97 on fusarium wilt of S. divaricata was 67.86% in pot experiment, which had good control efficiency.

Conclusion  Aspergillus terrestris MR-97 can effectively inhibit the mycelia growth of F. oxysporum and other pathogens, can colonize quickly in soil and has strong biocontrol effect. MR-97 strain, as a good source of biocontrol bacteria, has certain potentials of development and utilization.