Isolation of a novel Carica papaya b1;-amylase inhibitor with deleterious activity toward Callosobruchus maculatus
- 作者：L.R. Farias ; F.T. Costa ; L.A. Souza ; P.B. Pelegrini ; M.F. Grossi-de-Sá ; S.M. Neto ; Jr. ; C. Bloch ; R.A. Laumann ; E.F. Noronha ; O.L. Franco
- 关键词：Callosobruchus maculatus ; b1 ; -Amylase inhibitors ; Carica papaya ; Plant defense
- 刊名：Pesticide Biochemistry and Physiology
- 出版年：2007
- 期刊代码：182_00483575
- 类别：bio
- 出版时间：March 2007
- 卷：87
- 期：3
- 页码：255-260
- 文件大小：239 K
摘要
Cowpea (Vigna unguiculata) is a subsistence crop for small and poor farmers from Latin America and Africa. This culture is commonly damaged by cowpea weevil (Callosobruchus maculatus), which burrow into stored seeds to fed on. Due to impact of larval predation, several plant defense studies have been developed, indicating that b1;-amylase inhibitors are able to impede and/or reduce bruchids digestive process. In this report, a novel b1;-amylase inhibitor from papaya seeds (Carica papaya) with activity against cowpea weevil enzymes was purified and biochemical characterized. Peeled seeds were macerated and extracted with a 0.6 M NaCl and 0.1%HCl solution. Crude extract was precipitated with ammonium sulphate (100%). After dialyses, this rich fraction was applied onto a CM-Cellulose column and retained peak was submitted to an analytic reversed-phase column HPLC (Vydac C-18TP) yielding several peaks. Only one fraction, with molecular mass of 4562 Da, showed significant inhibitory activity against C. maculatus b1;-amylases. Otherwise, no inhibitory activities against mammalian b1;-amylases were observed. Bioassays using artificial seeds containing C. papaya b1;-amylase inhibitor rich fraction (0.5%and 1.0%) were also conduced showing that b1;-amylase inhibitors were able to increase larval mortality (50%) and also decrease insect fecundity and adult longevity. These results showed the presence of an b1;-amylase inhibitor from C. papaya seeds with high specificity to insect enzymes, indicating that this inhibitor probably could be used, through genetic engineering, in the construction of transgenic plants with enhanced resistance toward cowpea weevil.