The Inhibitory Activity of Triticale, Rye and Black Nightshade Seed Proteinaceous Extracts against Potato Tuberwor m Digestive α -Amylase and Protease

Abstract

Potato tuberworm, Phthorimaea operculella Zeller (Lepidoptera; Gelechiidae) is a worldwide pest of solanaceous crops. Larvae feed in side galleries in foliage, stems and tubers making chemical control unsuccessful, so oth er control methods should be applied. In recent years many plants have received genes tha t encode toxic proteins as a strategy to resist insect pests. In this study, optimal pH and temperature of digestive α -amylase and protease activities of potato tuberworm and the eff ect of triticale (X Triticosecale wittmack cv. Sanabad), rye ( Secale cereale L. cv. Danko) and black nightshade ( Solanum nigrum L.) seed proteinaceous extracts against enzymes activit ies were evaluated using starch 1% and azocasein 2% as a substrate, respectively. The optimum pH of α -amylase and protease activities was found to be highly alkaline . Enzymes inhibition assays showed that amylase activity was significantly affected by extr acts from triticale and rye by pH (P= 0.05; maximum effect at pH 9) and influencing of pr otease activity by extracts mentioned above did not vary by pHs 8-11 and 9-11, respective ly. Extracts from black nightshade seed had no effect on enzymes activity. Inhibition manner of various concentrations; 1.5, 0.75, 0.375, 0.187 and 0.093 (mg protein ml -1 ) of extracts were dose-dependent. Maximum inhibitory effect occurred at the highest concentra tion and the minimum was at the lowest concentration. In polyacrylamide gel assay, both en zymes, without inhibitors showed two isozymes, which at highest concentration of extract s, both bands disappeared or their intensity decreased. So, these proteins can be intr oduced to be encoded in producing resistant potato crops against potato tuberworm. Keywords: Cereals, Digestive enzymes, Potato tuberworm.