Characterization of Cycloartenol Synthase KcCAS Promoter Region from Mangrove Plant (Kandelia obovata Sheue, H. Y. Liu & J. Yong).

Cloning of Kandelia obovata (S. L.) Yong (2003) KcCAS gene from young roots (formerly known as Kandelia candel) has previously been reported and encoded a cycloartenol synthase. Fresh leaves of K. obovata that naturally grown in Okukubi River, Okinawa, Japan and used for DNA extraction. In this study, the KcCAS gene promoter was cloned through Genome walking, then sequenced and analyzed. An approximately 1 306 bp genomic DNA fragment of KcCAS promoter was obtained using the Universal Genome Walker kit. PLACE and PlantCARE analysis of the KcCAS promoter revealed that there was a number of regulatory elements in response to environmental signals and involved in the regulation of gene expression. Results showed that five kinds of cis-acting elements are regulated by hormone binding. These are the ABRE (TACGTG) involved in abscisic acid responsiveness, gibberellin-related GARE-motif (TCTGTTG), the P-box (CCTTTTG) involved in the gibberellin-responsive element, TCA-element (GAGAAGAATA) involved in salicylic acid responsiveness, and TGA-element (AACGAC) as an auxin-responsive element. Several important cis-acting elements in the KcCAS have been shown in other plants to be responsive to abiotic stress. These motifs were MBS (CAACTG), TC-rich repeats, and seven light responsive elements. The KcCAS promoter was also involved in the activation of defense genes in plants such as Box-W1 (TTGACC), dOCT (CaCGGATC), ARE (TGGTTT), and two circadian control elements (CAANNNNATC). The presence of multipotential regulatory motifs suggested that KcCAS may be involved in regulation of plant tolerance to several types of stresses. [ABSTRACT FROM AUTHOR]