Diseases control and plant growth promotion effect of three Trichoderma strains

Abstract:

[Background] Trichoderma sp. is an important biocontrol microorganism. Comparing the biological characteristics of different strains can provide information for multi-function biocontrol agent development. [Objective] To figure out the biological function differences among different strains by comparing and analyzing the preventive effects of Trichoderma virens T23 and the other two Trichoderma harzianum strains T22 and G30 and their biological characteristics. [Methods] Plate antagonism test was employed to compare the antagonistic effects of strains T23, T22, and G30 on plant pathogenic fungi. Gliotoxin was extracted from culture solution of strains T23, T22, and G30 by ethyl acetate extraction method and tested by high-performance liquid chromatography (HPLC). The antagonistic effects of the extracts on plant pathogenic fungi were compared by the hole drilling method, and the effects of strains T23, T22, and G30 on disease prevention were verified by plant inoculation in the greenhouse experiments. The conversion and utilization potential of strains T23, T22, and G30 to insoluble phosphorus was determined by using calcium phosphate and lecithin as the only phosphorus sources, respectively, and inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used for soluble phosphate detection. The main physiological and biochemical characteristics of strains T23, T22, and G30 were analyzed by the transparent ring method or chromogenic method. [Results] The plate antagonism rate of strains T23, T22, and G30 against Fusarium solani was 77%, 74%, and 48%, respectively, against Sclerotium rolfsii was 80%, 67%, and 24%, respectively, and against Botrytis cinerea was 93%, 62%, and 64% respectively. Neither strain T22 nor strain G30 carried gene clusters participating in gliotoxin biosynthesis, and no gliotoxin was detected in the culture solution of strains T22 and G30. The antibacterial rate of strain T23 extracts against S. rolfsii and B. cinerea was 40% and 65%, respectively. In the greenhouse experiment, strain T23 improved the emergence percentage (68%) of peanut seedlings under S. rolfsii stress and delayed the onset of disease in Rosa chinensis Jacq. for 16 days under B. cinerea stress. Strains T23 and T22 produced β-1,3-glucanase. Strains T23, T22, and G30 all possessed the ability to transform and utilize calcium phosphate. [Conclusion] Through comparative analysis, we have a further understanding of the disease prevention and growth-promoting effect of strain T23 and its physiological and biochemical characteristics. Strains T23, T22, and G30 have their characteristics and advantages in fungi antagonism and phosphorus solubilization. Strain T23 antagonizes pathogenic fungi by producing bacteriostatic natural products, which provides an important source for the development of fungus-derived biopesticides. In terms of growth promotion, the inorganic phosphorus solution mechanism of strain T23 needs to be further studied.