Biological control of gentian spot blight by the combination of endophytic fungi fermentation broth and traditional Chinese medicine extractions

Abstract

Gentian spot blight is a disease that decreases yields. Soil treatment can improve both plant growth and resistance to this disease. We investigated the effectiveness of endophytic fungi fermentation broth combined with traditional Chinese medicine (TCM) extractions in the biological control of gentian spot blight. We tested the anti-pathogen and growth-promoting properties of the endophytic fungi 3714, 272 fermentation broth, and 12 different TCM extractions in various solvents alone or in combination. The experiment was conducted in the field by treating gentian with various mixtures and examining their effect in controlling gentian spot blight. The combination of TCM water extractions and endophytic fungi fermentation broth, Anemarrhena asphodeloides Bge (ZM), ZM-272, Cnidium monnieri (L.). Cuss. (SCZ)-3714 and ZM-SCZ-3714 significantly controlled gentian spot blight at a control rate of more than 70%. Analyses of physiological and biochemical indexes, defense enzymes, soil enzymes, and soil properties suggest a mechanism for disease resistance and growth promotion. Specifically, different combination generally increases the number of microorganisms and soil enzyme activities in the rhizosphere of gentian, resulting in improvements in the accumulation of nutrients in soil, as well as the living environment of plants. The accumulation of nutrients in soil was improved by activating defense enzymes. The levels of secondary metabolites such as gentiopicrin increased, thus improving the disease resistance of gentian. Disease resistance was accomplished by directly suppressing the pathogen causing gentian spot blight on the surface of gentian plants and in the soil. These results provide a theoretical foundation for the biological control of gentian spot blight.