Resumen de Characterization of a vitis gai promoter in arabidopsis
The GAI (GA insensitive) gene plays a central role in plant gibberellin signaling. Mutations in a GAI gene can result in changes of plant architecture and other traits, thus providing potential opportunities for crop improvement. As a step towards exploring GAI variants for the improvement of grapevines (Vitis vinifera), we cloned a 2kb promoter region of the grape GAI gene from V. vinifera and characterized its activities in Arabidopsis thaliana, along with that of a GAI promoter from Arabidopsis and the 35S promoter from Cauliflower mosaic virus. These three promoters were each fused to the GUS reporter gene (ß-glucuronidase) (designated as pVv::GUS, pAt::GUS and p35S::GUS, respectively). GUS expression patterns driven by the three promoters were visually examined at both seedling and reproductive stages in transgenic Arabidopsis plants. Our results demonstrated that both VvGAI and AtGAI promoters showed strong activities in actively growing tissues including young shoots and new leaves, root tips, lateral root primordia, and young inflorescences. The GAI promoter activity was significantly reduced in older leaves, roots and stems, suggesting a very tight developmental control of GAI expression. Some subtle differences in the reporter activity were observed between VvGAI and AtGAI promoters in the stamen filaments of flowers and layers of the mature roots. The pVv::GUS construct had much stronger expression in stamen filaments than pAt::GUS while pAt::GUS showed more stained cell layers in the roots, suggesting that the regulatory control system for the same GAI gene could vary in different species. A major difference in expression activities between 35S and GAI promoters was found in roots. At seedling stages, strong reporter expression was observed for 35S::GUS in all root tissues including primary, lateral and tertiary roots, but there was almost no visible reporter expression in the primary roots of either pVv::GUS or pAt::GUS plants.
