Gene Cloning Of Glucosyltransferases Of Plant Hormones And Cultivation Of Transgenic Rice

Glycosylation is thought to be one of the most important modification reactions of plant secondary metabolites.This type of modification reactions can occur in plant hormones, peptides, proteins, metabolites, pathogen antigens and plant endogenous and exogenous toxic substances. Glycosyltransferases are the enzymes which specifically catalyze glycosylation reaction and transfer activated sugar from a donor (usually UDP-glucose) to acceptor molecules. Additionally, glycosylation modification often change the molecules with respect to biological activity, water-solubility, transport characteristics in intracellular and plant, subcellular localization and binding properties with receptors, and also can reduce or eliminate the toxicity of endogenous and exogenous substances of the plant molecules.Therefore, glycosylation plays a key role in maintaining cell homeostasis, thus likely participating in the regulation of plant growth, development and in the defense responses to stress environments.UGT76C2and UGT74E2are the members of glycosyltransferase family1of the Arabidopsis thaliana. UGT76C2is one of the cytokinin N-glucosyltransferases and can catalyze cytokinin to form its N-glucosides. UGT74E2has been demonstrated to be an auxin glycosyltransferase. Over-expression of these genes in transgenic Arabidopsis thaliana has resulted in different physiological phenomena, such as the changes of growth morphology, and the promotion of the ability to stress environment resistance. In this study, UGT76C2and UGT74E2had been transformed into the Oryza sativa L.ssp.japonica, and the transgenic rice plants over-expressing these genes had been gotten. This work laid the foundation for improving the agronomic traits of rice by hormone regulation and possibly providing the theoretical and technical basis for the crop breeding.Cytokinin is one type of the main hormones in plant, and its role is involved in many aspects of plant growth and development. The glycosyltransferases of cytokins had been studied in Arabidopsis thaliana, but not yet in rice. In this study,14 candidate genes of cytokin glycosyltransferases were cloned, and expressed using prokaryotic expression system.The recombinant proteins of these genes were also purified. This work will help the further study toward the identification of cytokinin glycosyltransferases in rice.