Toxicity of Seed extracts of Pea Cultivars in relation to Trypsin inhibitory activity

By : Amarjit K. Nath, Akhilesh Thakur

Page No: 243-250

Abstract
Purpose: Trypsin inhibitors in the seeds of legumes can act as a feeding deterrent for insects by disrupting midgut proteases. This paper investigates trypsin inhibitors in pea cultivars. Design/Methodology/Approach: The seeds of seven different pea cultivars and the cultures of root knot nematode Meloidogyne incognita were used for biological screening of trypsin inhibitory activity (TIA). This was followed by partial purification of trypsin inhibitor from the screened pea cultivar by ammonium sulphate precipitation, ion exchange chromatography on DEAE-Sephadex (A50) column and gel filtration through Sephadex G-200 column. Findings: Field pea with maximum TUI/g seed weight and percent mortality of Meloidogyne incognita was then partially purified. A linear correlation between time of incubation and TIA was found till 25 min of incubation, whereas, per cent inhibition was linearily correlated to the amount of inhibitor upto 68.1 per cent inhibition. The inhibitor showed maximum TIA at 37?C indicating thermolabile nature. It had two pH optima at pH 7.5 and 9.0. Km value was found to be 0.227 mM. Trypsin inhibition was of non-competitive type with inhibitor constant (Ki) value in the region of 0.25 ?M. Originality/Value: Invaluable information on trypsin inhibitors in case of native legumes of Himalayan origin has been found. Outcomes of this study can be of immense importance in the development of insect resistant transgenic plants.

Authors :
Akhilesh Thakur and Amarjit K. Nath : Asstt. Professor, Faculty of Sciences, Abhilashi University, Chail Chowk, Mandi (H.P.)-175028, India **Professor, Department of Biotechnology, U.H.F. Nauni, Solan-173230, India