Induction of Defense Enzymes in Trichoderma harzianum Treated Groundnut Plants against Macrophomina phaseolina

Antagonistic activity of Trichoderma harzianum isolated from the rhizosphere of groundnut was determined in vitro. T. harzianum decreased the root rot incidence in vivo. Potential of T. harzianum to induce systemic resistance was tested in groundnut against Macrophomina phaseolina . Biochemical changes in T. harzianum treated plants, M. phaseolina inoculated plants and healthy plants were assayed at different stages of infection. Treatment with T. harzianum and challenge inoculation of M. phaseolina enhanced induction of defense enzymes such as peroxidase (PO) and polyphenol oxidase (PPO) and defense compounds like total phenol and ortho-dihydric phenol. Total phenols, ortho-dihydric phenols, peroxidase and polyphenol oxidase activities increased at different stages of infection. T. harizanum treatment along with challenge inoculation of the pathogen significantly increased the activity of peroxidase and polyphenol oxidase by about 28.2 % and 95.5%, respectively, in roots at stage 2 compared to untreated plants. Increased levels of peroxidase and polyphenol oxidase were induced in root and shoot of treated plants indicating the systemic protection offered to groundnut by T. harzianum . The observations revealed that T. harzianum was capable of inducing systemic resistance against M. phaseolina by eliciting the production of defense enzymes.