Identification of strain KF-43-1 against cotton verticillium wilt and comparison of biocontrol effects among three application methods in the field

Abstract:

[Background] Cotton verticillium wilt, known as the “cancer” of cotton, causes serious harm to the yield and fiber quality of cotton. Biocontrol with eco-friendliness and high safety has become the key research content in the prevention and treatment of cotton verticillium wilt. Therefore, developing new biological agents to control cotton verticillium wilt is of great significance for cotton production. [Objective] To preliminarily identify and characterize the actinomycete strain KF-43-1 with antagonistic effect on cotton verticillium wilt and determine the best application method of this strain, so as to provide support for the development of new biocontrol agents against cotton verticillium wilt. [Methods] Strain KF-43-1 was identified based on molecular evidence, and its morphological and growth characteristics were observed. The inhibitory effects of KF-43-1 on pathogenic fungi were determined. The physiological and biochemical characteristics of the strain were determined, and verify the field control effect of different uses of actinomyces KF-43-1 on cotton verticillium wilt. [Results] Strain KF-43-1 was identified as Streptomyces albogriseolus. It showed inhibitory effect of 82.05% on the pathogen V991, which was higher than that of the actinomycete strain 5406. It demonstrated the inhibitory effect of 25.81% on Fusarium oxysporum ST89, which was lower than that of strain 5406. Strain KF-43-1 had no fluorescence reaction and can liquefy gelatin, hydrolyze starch, yield positive results in the methyl red test, and produce melanin. However, it did not have the ability to decompose cellulose. Strain KF-43-1 grew well at pH 7.0–8.0, and was inhibited in Actinomycetes culture medium with 2% salt concentration and showed some salt tolerance. The effect of antagonistic KF-43-1 on cotton verticillium wilt was higher than that of centrifuge coating and centrifuge spraying, indicating that antagonistic KF-43-1 had better inhibition effect on cotton verticillium wilt outbreak after colonizing in soil. [Conclusion] The actinomycete strain KF-43-1 serves as a candidate for the development and application of biological agents for the prevention and control of cotton verticillium wilt.