Screening of Trichoderma spp. to control Sclerotinia sclerotiorum-induced sclerotiniose in Fritilla ussuriensis Maxim. and the laboratory control effect

Abstract:

[Background] Sclerotinia sclerotiorum-induced sclerotiniose in Fritilla ussuriensis is one of the main bulb diseases, which causes huge loss to the industry of F. ussuriensis. [Objective] To screen Trichoderma strains against S. sclerotiorum. [Methods] Eligible strains were identified based on plate confrontation assay, two-sealed-base-plates method, disc filter membrane method, and the test of the inhibitory effect of fermentation broth. Headspace solid-phase microextraction was used to detect the composition of volatile components of Trichoderma strains with better antagonistic effect. The β-1,3 glucanase activity of strains was assayed with the DNS method. Experiment on in vitro bulbs was carried out to verify the effect on S. denigrans. [Results] Strains F1, F2, and D6 had strong inhibitory effect on the growth of S. denigrans and the inhibition rates were 91.06%, 87.00%, and 86.12%, respectively. According to the disc filter membrane test, S. denigrans did not grow on the agar with F2, C6, D3, F4, A26, B30, D4, and D6 and the inhibition rate was up to 100%. The two-sealed-base-plates test indicated that E12 and A26 had the most obvious inhibitory effect, with the inhibition rates of 74.96% and 75.86%, separately. The test on the fermentation broth showed that D3 had the strongest inhibitory effect, which could completely inhibit the growth of S. denigrans (inhibition rate: 100%). The volatile products of A26, D4, E8, E17, and D3 were analyzed by GC/MC, and the antifungal active substances of E17 such as 6-n-pentyl-2H-pyran-2-one were found. F1 was found to have the highest β-1,3 glucanase activity. According to the laboratory test, D3 can significantly inhibit the pathological changes of sclerotiniose in bulbs of F. ussuriensis and has potential biocontrol activity. [Conclusion] Trichoderma D3 has great potential for the control of S. denigrans.