ABSTRACT: Alternaria leaf spot disease is a major threat to sesame (Sesamum orientale L.) caused by Alternari
asesami. Induced resistance is an alternative to systemic disease resistance response of plants. The present study aims
to evaluate Trichoderma species efficacy as biocontrol via induction of resistance against A. sesami in sesame species.
During in vitro bio control test, T. harzianum colonize and parallely inhibit the growth of the fungal pathogen.
Expression of various defence related enzymes observed in sesame induce resistance against the pathogen infection in
the host. T. harzianum coupled with inoculation of A. sesami enhance the remarkable induction of defence enzyme
such as peroxidase (POX), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL) and also the phenolic
content compared with the control. The enzyme activity increased from 48 h of sampling and peaked at 72 h and then
decreased after 72 h. In greenhouse and field experiments, soil treatment with a powder formulation of T. harzianum
two weeks before planting or at the time of planting reduced significantly the incidence of diseases on both the wild
and cultivar Thilarani.The results demonstrate that T. harzianumcan be successfully applied as a biological control
against Alternaria leaf spot disease in sesame.
Keywords: Sesame, Leaf spot disease, Alternari asesami, Trichoderma harzianum, Biocontrol