The seeds of ten genotypes and twenty-nine wild relatives of okra were analysed for the presence of trypsin, chymotrypsin, and Helicoverpa gut proteinases (HGPs) inhibitors (HGPIs), with the aim to identify potent inhibitors of H. armigera gut proteinases. Proteinase inhibitors (PIs) obtained from wild relatives of okra exhibited stronger inhibition of HGPs than the genotypes of okra. In in vitro inhibitory assay against HGPs, A. tuberculatus 90396 and 90515 showed high tryptic inhibitory (71.8% and 69.2%), chymotryptic inhibitory (68.5% and 66.2%), and Helicoverpa gut proteinase activity (70.2% and 68.2%). In electrophoretic profile showed the same variation in the number of trypsin inhibitors (TIs), chymotrypsin Inhibitors (CIs), and HGPIs isoforms with different intensities, whereas genotypes of okra mostly showed monomorphic profile. Maximum eight HGPIs isoforms were found in A. tuberculatus (90396 and 90515). In bioassay studies, significant reduction in weight of H. armigera larvae was found, when larvae fed on PIs obtained from A. tuberculatus (90396 and 90515). Thus, the result of the present investigation indicates that further exploration of PIs obtained from A. tuberculatus (90396 and 90515) will be helpful for developing PIs-based insect resistance management strategies. 1. Introduction Helicoverpa armigera, Hubner (Lepidoptera: Noctuidae), a highly devastating, polyphagous crop pest, has a broad host spectrum and causes a significant yield losses in many agriculturally important crops, like cotton, chickpea, pigeon pea, corn, maize, tomato, okra, sorghum, pearl millet, sunflower, and groundnut [1]. Thirty percent of all pesticides used worldwide are directed against H. armigera which resulted in high levels of insecticide resistance in this pest. Insecticide resistance in H. armigera is widespread problem in India, Pakistan, China, Australia, Thailand, and Indonesia [2]. The use of Bacillus thuringiensis (Bt) either in the form of formulation and transgenic plant may lead to develop resistance in insect in a short period of time, since many insect pests have developed resistance to Bt-like chemical pesticides [3]. Therefore, it is important to search and develop alternative methods of controlling this pest and proteinase inhibitors (PIs), constituents of natural plant defense system, promises to lead in this aspect in near future [4]. Plant synthesizes various proteinaceous compounds against an insect attack, among the several plant defense proteins. PIs are abundantly present in seeds and storage tissues which represent up to 10% of the
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