Screening and identification of the biocontrol Streptomyces against tomato Botrytis cinerea

Abstract:

[Background] Tomato grey mould caused by Botrytis cinerea is an important fungal disease. Biological control can be an effective measure in prevention and control of this disease, due to its environmentally-friendly and not easy to develop pathogen resistance characters. [Objective] To screen antagonistic Streptomyce sp. with broad-spectrum antifungal activity, confirm the biocontrol effects and define the classification status of the antagonistic strain. [Methods] Antagonistic actinomycetes were obtained by agar block method, the inhibition spectrum of strain T22 was detected using confrontation culture and mycelia growth assays. Biocontrol effects of strain T22 was detected using enzymes production, detached leaves and seed germination assays. Strain T22 was identified to species level based on morphological and cultural features, physiological-biochemical characters, as well as molecular methods. [Results] A total of 14 antagonistic isolates were screened from 56 soil actinomycetes, among which strain T22 showed obvious inhibition effect on Botrytis cinerea and other fungi. The inhibition rate of strain T22 on Botrytis cinerea, Monilinia fructicola and Fusarium oxysporum f. sp. cucumerinum were 84.6%, 81.5% and 79.1%, respectively. In addition, the culture filtrate of strain T22 displayed obvious disease reduction effect (55.1%) on detached leaves of tomato plants. The hypocotyl length, radical length and seed vigor index were increased by 15.1%, 29.7% and 43.9%, respectively, with 100-fold dilution treatment. Strain T22 was identified as Streptomyces alboniger based on morphological and cultural features, physiological-biochemical characters, as well as multiple sequences analyses. [Conclusion] Streptomyces alboniger T22 had obvious antifungal activity, extracellular hydrolase production ability, disease reduction and seed germination promotion effects on tomato, with application potential as biocontrol agent against tomato grey mould.