Isolation and identification of a thermostable Trichoderma strain for banana growth promotion in tropic area

Abstract:

[Objective] In order to screen a safe and efficient thermotolerant Trichoderma strain to be used in tropical areas to effectively promote banana production, Trichoderma strains that can survive under a wide temperature range were isolated from agricultural soils collected from tropical areas. Then the biofertilizers containing Trichoderma isolates were developed and their effects on banana Fusarium wilt disease, crop yield and fruit quality were explored. [Methods] Trichoderma strains were screened by series-dilution separation method, and then re-screened according to the growth conditions of Trichoderma strains at different temperatures. Further antagonistic abilities against Fusarium oxysporum f. sp. cubense tropical race 4 (FOC 4) and the produced enzyme activities of Trichoderma strains were tested to isolate efficient thermotolerant Trichoderma strain. Then the effects of the biofertilizers developed containing the above selected Trichoderma strains on banana Fusarium wilt disease, crop yield and fruit quality were studied under field condition. Finally, the selected strain with best effect on improving crop production was identified using ITS and tef1 sequencing. [Results] Four thermotolerant Trichoderma strains were isolated from the soil collected from Hainan province, and all of these four strains could grow under between 20 ℃ and 40 ℃. Among them, strain JS84 grew fastest at 40 ℃, displayed the highest inhibition rate against FOC 4 and showed highest enzyme activities. Field experiment showed that application of biofertilizer containing Trichoderma JS84 (JS84) significantly suppressed banana Fusarium wilt disease incidence, improved the quality of banana fruit and soil nutrients condition. Strain JS84 was identified as Trichoderma citrinoviride based on both ITS and tef sequence. [Conclusion] Strain JS84 classified as Trichoderma citrinoviride with a wide growth temperature was successfully isolated from tropic area in China. Biofertilizer developed based on this strain exhibited an excellent ability in suppressing banana soil-borne Fusarium wilt disease and improving crop yield.