Exploration and Utlization of Promoters from Dicot Plats

Abstract

The highly expressed promoters used in genetic engineering have been isolated from viruses. The commercially available promoters have been patented and the scientists have to address the Intellectual Property Rights issues related to patented promoters. The exploration of strong dicot promoters is needed for the expression of transgenes by our local researchers for the evaluation of their transgenes. The dicot promoters (β-TbBr promoter, β-TbSt promoter and susy-Sl promoter) were explored and isolated from potato, turnip and tomato respectively. The promoter sequences and their deletion mutants consist of various motifs for light response, hormonal response and stress response. Maximum light responsive motifs were detected in β-TbSt and susy-Sl promoters. The full length β-TbSt and susy-Sl promoters were expressed in tobacco and cotton tissues through transient assay and their expression was maximum in major tissues of these selected dicot plants. The strong β-Glucoronidase (GUS) expression was observed in roots, stem, leaves, flowers, trichomes and siliques of transgenic Arabidopsis thaliana under the β-TbSt and susy-Sl promoters. The full length β-TbBr promoter also expressed GUS gene in various tissues of tobacco and cotton through transient assay but the deletion mutants of this promoter were expressed only in anthers of transgenic lines of Arabidopsis. The deletion mutants of susy-Sl promoter showed strong constitutive GUS expression in roots, stems, leaves, flowers, trichomes and siliques of transgenic A.thaliana tissues.The smallest deletion mutant (679bp) of susy-Sl promoter showed optimal promoter activity in transgenic A. thaliana. The deletion mutants of β-TbSt promoter also expressed GUS gene in major tissues of A. thaliana but the expression was not good in roots due to removal of some of the root specific motifs and light inducible motifs. The β-TbBr promoter showed flower specific expression in A. thaliana. The β-TbSt promoter and susy-Sl promoter were found highly constitutive while the full length β-TbBr promoter can be utilized for the expression of salt inducible genes under stress conditions and the deletions of this promoter can be utilized for the floral specific expression of transgenes in plant genetic engineering.