Analysis of Insect Gut Enzymes and Verification of Regulatory Effects of Specific Inhibitors against Eating Damages on Food Seeds.

点击翻译按钮获取中文摘要

Detailed analysis were conducted of cysteine proteinases of Sitophilus zeamais (Coleoptera), a rice-seed insect pest, to elucidate their properties and physiological functions at the molecular level. It was found that the cysteine proteinases comprise multiple molecular species originating from a gene family and also that one of the species is a central enzyme. involved in damaging the seeds. The result made us try to develop a transgenic rice cultivar with oryzacystatin or corn cystatin expressed at a higher level. For the trial, we first fused a cystatin cDNA and a hyglomycin-resistant gene to Ca MV35S promoter and then introduced the fusion gene to rice protoplasts by electroporation or using an agrobacterium-mediated system. The consequently regenerated transformant was found to express 10-15 times more cystatin than the non-transformant (normal rice) used as control. The cystatin expressed in the transformant seeds, when purified, showed a strong inhibitory activity (ICィイD250ィエD2 : 〜10ィイD1-8ィエD1M) toward cathepsin H as well as toward the Sitphilus cysteine proteinase. We then produced transgenic rice of this type at a field scale and harvested the seeds. An investigation to find out the antipest and even lethal effects of the seeds themselves to successfully progressing.