Abiotic elicitors mediated resistance and enhanced defense related enzymes in Capsicum annuum L. against anthracnose disease

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The present study was intended to investigate the efficacy of abiotic elicitors (L- isoleucine, L- leucine, L- methionine, L- phenylalanine and L- proline) to induce growth and resistance in chilli against anthracnose disease caused by Colletotrichum capsici. Among the different concentrations of abiotic elicitors tested, L- leucine treatment at 50mM concentration for three hour duration offered a maximum increase in seed germination (89%) and seedling vigor (947.2) followed by other abiotic treatments. Under greenhouse conditions, significant protection against anthracnose disease was recorded by L- leucine (65%) followed by L- proline (62%) and it was also noted that these elicitors required a minimum of four days after challenge inoculation to build up maximum resistance to anthracnose disease. Apart from disease protection, abiotic elicitors were also found effective in enhancing vegetative growth parameters. At the biochemical level, the maximum activity of Phenylalanine ammonia lyase (PAL), Peroxidase (POX) and total phenolic content was observed upon treatment with L- leucine. There was an increase in PAL, POX and total phenolic content up to one to two fold in inducer treated challenge inoculated seedlings when compared to susceptible inoculated seedlings which were similar to that of resistant inoculated seedlings. Increased activity of defense enzymes in inducer treated seedlings are in correlation with the disease protection studies.