兴安落叶松UGPase和UGDH增强转基因植物营养生长和耐寒性的分子机理

UDP-葡萄糖焦磷酸化酶（UGPase）和UDP葡萄糖脱氢酶（UGDH）分别是植物纤维素和半纤维素生物合成途径中的关键酶。在前期研究中我们克隆了兴安落叶松的UGPase 和UGDH基因（分别命名为LgUGPase和LgUGDH）并利用遗传转化拟南芥的方法对其功能进行了调查。结果显示：LgUGPase和LgUGDH的过量表达不仅提高了转基因拟南芥的纤维素和半纤维素含量，而且显著促进了其营养生长。另外，LgUGDH基因的过量表达显著提高了转基因拟南芥的耐寒性，转基因植株在4℃条件下能够保持正常生长。该结果显示出这两个基因在牧草及林木遗传育种中的重要应用价值。本申请项目拟利用多种分子生物学技术，深入探究这两个基因增强转基因植物营养生长和抗寒性的分子机理，进而为揭示LgUGPase和LgUGDH基因的功能特性及利用它们进行作物及林木的遗传改良提供理论和实验依据。

UDP-glucose pyrophosphorylase (UGPase) and UDP-glucose dehydrogenase (UGDH) are key enzymes in the biosynthesis pathway of cellulose and hemicelluloses, respectively. In previous studies, we isolated orthologs of UGPase and UGDH, referred to as LgUGPase and LgUGDH respectively, from Larix gmelinii using homology-based cloning method, and investigated functions of the two genes by transforming Arabidoposis. The results showed that overexpression of LgUGPase and LgUGDH increased the contents of celluloses and hemicelluloses, and significantly enhanced vegetative growth of transgenic A. thaliana. On the other hand, overexpression of LgUGDH significantly enhanced cold-tolerance in transgenic A. thaliana, the transgenic plants showed normal vegetative growth under low-temperature (4°C) condition. These results revealed the important value of LgUGPase and LgUGDH in genetic improvement of forages and forest trees. In the project, we plan to analyze the molecular mechanism of LgUGPase and LgUGDH enhancing vegetative growth and cold-tolerance in transgenic plants using molecular biological techniques, such as mRNA sequencing, fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP) etc. The expectant results will provide theoretical and experimental basis for understanding functions and characteristic of the LgUGPase and LgUGDH genes, and for their application in genetic breeding of forages and forest trees.