谷氨酰胺合成酶PpGS2基因调控草地早熟禾耐旱耐氮素贫瘠的机制

Water and nitrogen as the most important factors limit the ornamental quality of turfgrass. An effective innovation strategy for water and nitrogen resource conservation and environmental friendly is using genetic methods to improve the drought resistance and lower nitrogen tolerance of the world famous Kentucky bluegrass, and further to enhance its water and nitrogen use efficiency. Former study in our group revealed that the gene of chloroplastic glutamine synthetase PpGS2 possessed the unique functions in regulating nitrogen metabolism and drought resistance as well as lower nitrogen tolerance of Kentucky bluegrass in response to different water and nitrogen conditions. However, these involving mechanisms were not clear. In this study, molecular techniques of gene overexpression and gene knockout will be used for transgenic the gene PpGS2 to different genotypes of Kentucky bluegrass. Measurements on the transgenic plants phenotypic traits, the physiological attributes, some important water-nitrogen relation genes expression are included and will be used for further revealing the functions and regulating mechanism of the PpGS2. The results of this research will be important to support the genetically innovation of new Kentucky bluegrass cultivars in China.

制约草坪观赏质量的主要因素是水分和氮营养。通过基因改良草地早熟禾耐旱和耐氮素贫瘠特性，从而提高水肥利用效率，是创新这一世界著名草坪草新种质及节约资源和环境友好的重要途径。项目组前期研究发现草地早熟禾叶绿体型谷氨酰胺合成酶PpGS2基因具有响应不同水氮条件并参与调解草地早熟禾氮代谢及耐旱和耐低氮能力的功效，然而其作用机理尚不明确。本项目基于前期研究基础，拟进一步通过基因超表达和敲除技术对草地早熟禾的PpGS2基因调控氮代谢和抗旱性的功能进行系统研究，测定植株表型特征、生理代谢和重要相关基因的表达，以揭示其基因功能和调控机制。研究成果可为培育和创新我国草地早熟禾草坪新品种提供理论依据和技术支撑。

【项目背景】制约草坪观赏质量的主要因素是水分和氮营养。通过基因改良草地早熟禾耐旱和耐氮素贫瘠特性，从而提高水肥利用效率，是创新新种质的重要途径。前期研究发现，草地早熟禾叶绿体型谷氨酰胺合成酶 PpGS2 基因具有响应不同水氮条件并参与调解草地早熟禾氮代谢及耐旱和耐低氮能力的功效，然而其作用机理尚不明确。本项目基于前期基础，拟进一步通过基因超表达和敲除技术对草地早熟禾的 PpGS2 基因调控氮代谢和抗旱性的功能进行系统研究，测定植株表型特征、生理代谢和重要相关基因的表达，以揭示其基因功能和调控机制。研究成果可为培育和创新我国草地早熟禾草坪新品种提供理论依据和技术支撑。【研究内容】构建 PpGS2 基因的植物超表达载体与敲除载体，利用基因枪转化草地早熟禾。以野生型草地早熟禾作对照，检测草地早熟禾转基因植株的生长发育、表型特征、氮素和水分生理代谢的调节和表达差异，基于植物发育和细胞生理学理论，分析和探究草地早熟禾 PpGS2 基因对转基因材料耐旱耐氮素贫瘠的的作用和调节机理。【结果】获得过表达植株3株，基因编辑植株1株。过表达草地早熟禾出现明显的表型变化，叶宽、叶色、分蘖能力、生长速度等方面出现较大差异。转基因株系的氮代谢和氧化酶活力明显强于野生型。位于 PpGS2 下游的基因的表达量明显表达水平提高。潮霉素靶基因验证编辑载体已经进入草地早熟禾中。【意义】探明草地早熟禾谷氨酰胺合成酶 PpGS2 基因响应水分和氮素胁迫过程中的基本功能。获得了表型差异明显的草地早熟禾转基因株系，为后期草地早熟禾品种的选育提供基础材料。