Induction of induced systemic resistance in capsicum chilli against Colletotrichum truncatum through fungal biocontrol agents

Abstract

To induce the systemic resistance in capsicum against Colletotrichum truncatum an experiment was conducted with two biocontrol agents viz., Trichoderma harzianum and Trichoderma asperellum in pot culture. The induced resistance was monitored by increase in activities of five defense related enzymes viz., peroxidase (PO), polyphenol oxidase (PPO) phenylalanine ammonia lyase (PAL), catalase (CAT), and superoxide dismutase (SOD) and the accumulation of phenols and β -1,3-glucanase were also noticed in capsicum upon challenge inoculation with C. truncatum, the causal agent for anthracnose or fruit rot in capsicum. The activities of defense enzymes reached a peak at eight days after inoculation (DAI) with the pathogen. Native PAGE analysis revealed the expression of an additional isoforms of PO and PPO were observed in biocontrol agents treated seedlings due to induced systemic resistance (ISR) introduction. Prior treatment of capsicum seedlings with biocontrol agents triggered the plant defense mechanism in response to infection by C. capsici. Hence, it is speculated that among the various direct antagonistic tools, ISR is also the one indirect tool by which the tested biocontrol agents afforded resistance to capsicum against the pathogen.