Combined Use of <i>Trichoderma atroviride</i> CCTCCSBW0199 and Brassinolide to Control <i>Botrytis cinerea</i> Infection in Tomato

Abstract

Tomato gray mold caused by <i>Botrytis cinerea</i> is one of the main diseases of tomato and significantly impacts the yield and quality of tomato fruit. The overuse of chemical fungicides has resulted in the development of fungicide-resistant strains. Biological control is becoming an alternative method for the control of plant diseases to replace or decrease the application of traditional synthetic chemical fungicides and genus <i>Trichoderma</i> is widely used as a biological agent for controlling tomato gray mold. Brassinolide (BR) is a plant-growth-promoting steroid. To enhance the efficiency and stability of <i>Trichoderma</i> activity against <i>B. cinerea</i>, an optimal combination of <i>Trichoderma atroviride</i> CCTCCSBW0199 and BR that controls <i>B. cinerea</i> infection in tomato was identified. Strain CCTCCSBW0199 was found to have antagonistic activity against <i>B. cinerea</i> both in vitro and in vivo. In addition, a fermented culture of chlamydospores and metabolites, or metabolites only of strain CCTCCSBW0199 also reduced growth of <i>B. cinerea</i>. BR reduced growth of <i>B. cinerea</i> and had no effect on the sporulation and growth of <i>Trichoderma</i> spp. An application of metabolites of a <i>Trichoderma</i> sp. + BR reduced gray mold on tomato leaves by approximately 70.0%. Furthermore, the activities of induced defense response-related enzyme, such as peroxidase, superoxide dismutase, catalase, and phenylalanine ammonia-lyase were increased in tomato plants treated with a <i>Trichoderma</i> sp. <i>+</i> BR. Our data suggested that applying a mix of metabolites of <i>T. atroviride</i> CCTCCSBW0199 + BR was effective at reducing gray mold of tomato and may lay a theoretical foundation for the development of novel biofungicides.