IMPROVED TRICHODERMA STRAINS AS BIOCONTROL AGENTS, METHOD FOR OBTAINING THE SAME AND USE THEREOF FOR CONTROLLING DISEASES CAUSED BY PHYTOPATHOGEN FUNGI.
The present invention describes the obtention of Trichoderma strains over-producing various lytic enzymes acting as phytopathogen fungi antagonists due to their high mycoparasitic activity. A coding Trichoderma virens gene was clonned for a mitogen-activated protein kinase (MAP kinase), said gene being related to the mycoparasitic response, conidiation and biocontrol observed in Trichoderma. The Trichoderma strains having a suppressed expression of the isolated MAP kinase gene showed an apparent increase in the expression level of genes related to mycoparasitism (MRGs) under mycoparasitism simulated conditions and while brought into direct contact with the pathogen of Rhizoctonia solani plants. The biocontrol assays consistently showed that the inventive strains were substantially more effective in the control of diseases than wild strains or a chemical fungicide. Furthermore, the inventive strains abundantly sporulated in submerged cultures, a condition which normally does not lead t o the formation of spores in a wild strain.La presente invención se refiere a cepas de Trichoderma sobre-productoras de varias enzimas líticas para utilizarse como antagonistas de hongos fitopatógenos debido a la incrementada actividad micoparasítica que presentan. Se clonó un gen de Trichoderma virens codificante para una proteín cinasa activada por mitógeno (MAP cinasa), el cual está relacionado con la respuesta micoparasítica, la conidiación y el biocontrol observado de Trichoderma. Cepas de Trichoderma con la expresión suprimida del gene MAP cinasa aislado, mostraron un claro incremento en el nivel de expresión de genes relacionados al micoparasitismo (MRGs) bajo condiciones de micoparasitismo simulado y durante la confrontación directa con el patógeno de plantas Rhizoctonia solani. De manera consistente, ensayos de biocontrol demuestran que las cepas de la invención fueron considerablemente más efectivas en el control de enfermedades que la cepa silvestre o un fungicida químico. A
