Differential Inhibition of Helicoverpa armigera (Hubner) Gut Proteinases by Proteinase Inhibitors of Okra and It's Wild Relatives.

Shilpa K Udamale,T B Ugale,M P Moharil,J M Mankar

doi:10.5402/2013/632173

Shilpa K Udamale, T B Ugale + Show 2 more

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https://doi.org/10.5402/2013/632173

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Journal: ISRN Biotechnology	Publication Date: Feb 3, 2013
Citations: 24	License type: CC BY 3.0

Affiliation: Dr Panjabrao Deshmukh Krishi Vidyapeeth

Abstract

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.

Highlights

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
Parbhani Kranti AKO-107, Arka anamika, and AKO-37 possessed four HGPIs isoforms, whereas Arka bahar consists only one HGPIs isoforms (Figure 2(c)). These results clearly showed that proteinase inhibitors (PIs) from wild relatives of okra A. tuberculatus (90396 and 90515) exhibited strong inhibitory potential against Helicoverpa gut proteinases (HGPs)

Summary

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. 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]. PIs are abundantly present in seeds and storage tissues which represent up to 10% of the total protein [5]. PIs act as antimetabolic proteins, which interfere with the digestive process of insects. PIs are effective against phytophagous insects and microorganisms. The defensive capabilities of PIs rely on inhibition of proteinases present in insect guts or secreted by microorganisms, causing a reduction in the availability of amino acids necessary for their growth and development. Most PIs interact with their target proteinases by contact with the active (catalytic) site of the proteinase resulting in the formation of a stable proteinaseinhibitor complex that is incapable of enzymatic activity [6]

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