Activity of defense related enzymes and gene expression in pigeon pea (Cajanus cajan) due to feeding of Helicoverpa armigera larvae

The biochemical and molecular basis of the defense in a mild tolerant (ICPL-332) and susceptible (ICPL-87) cultivars of pigeon pea (Cajanus cajan) due to Helicoverpa. armigera infestation was studied. We found that feeding by the larvae generated H2O2 in a localized manner and activity was observed upto 12h (hrs) of with a sharp decline within 24h. Similarly, PPO activity was also detected till 12h of treatment, which decreased after 24h of feeding by larvae. The activity of trypsin inhibitor was detected in all the treatments when assayed at 12 and 24h after larval feeding. The expression of defense genes like the Pre-hevein-like protein PR-4 precursor (PR-4), protease inhibitor/seed storage/LTP family protein (Ltp) were significantly up-regulated in ICPL-332 upon infestation after 12h as compared to ICPL-87, whereas the endo 1, 4 --glucanase (Kor-1) gene was expressed in both the cultivars after 24h of infestation. Both the cultivars varied with respect to the induction of defense-related genes during larval feeding, both the PR-4 and Ltp genes appeared to be important for defense against H.armigera in pigeon pea. Thus, the present study revealed an insight of herbivore-induced biochemical and molecular changes in pigeon pea.