Endophytic fungus Beauveria bassiana induces antioxidant enzyme activities and enhances the growth of Rhizoctonia solani-infected potato plants

Abstract

The physiological and biochemical changes in potato plants colonized by the endophytic form of the entomophatogenic fungus Beauveria bassiana (Ascomycota: Hypocreales) were analyzed under biotic stress caused by infection with the phytopathogen Rhizoctonia solani (Basidiomycetes: Ceratobasidiales). A high level of plant colonization by entomopathogenic endophyte was observed, and infection with R. solani did not have a significant effect on the degree of plant colonization. The colonization of potatoes by B. bassiana compensated for the growth retardation of Rhizoctonia-infected plants, especially the roots, and significantly reduced Rhizoctonia damage to stems and developing stolons. Inoculation of plants with both fungi resulted in an increase in antioxidant activity, with B. bassiana contributing to this effect. There were significant increases in the activity of the following antioxidant enzymes: peroxidases, superoxide dismutases, polyphenol oxidases and phenylalanine-ammonia-lyase. B. bassiana triggered the host plant’s defense system, namely a complex of antioxidant enzymes, to overcome biotic stress caused by R. solani. Therefore, B. bassiana is a promising modulator of plant defense metabolism against phytopathogens.