Effect of foliar spray of elicitors on status of defense proteins in relation to mustard aphid infestation in crop Brassica cultivars

Mustard aphid, Lipaphis erysimi Kalt., is the key insect pest of crop Brassicas causing significant reduction in crop yield. In the present study, widely grown Brassica cultivars RLC-1 (Brassica juncea) and GSC-6 (Brassica napus) were treated with elicitors salicylic acid (SA) and jasmonic acid (JA) at 0.5mM and 1mM concentration via foliar spray (given at 40 and 60 days after planting (DAP). Their effect was evaluated in terms of total soluble protein content and activities of defense proteins (peroxidase, protease inhibitor, polyphenol oxidase, amylase inhibitor and lectins) in relation to aphid infestation in leaf tissue. SA and JA application caused significant increase in activities of defense proteins as well as total soluble proteins. JA at 1mM concentration was most effective in both Brassica cultivars. The 2nd foliar spray gave a booster response. The aphid population/plant reduced significantly in both the cultivars with JA as well as SA. POD and PPO registered negative correlation with aphid population count. SA and JA foliar applications seemed effective against mustard aphid through positive modulation in activities of defense proteins.