Overexpression Of Glutamine Synthetases Confers Transgenic Rice Herbicide Resistance And Nitrogen-poor Soil Tolerance

Glutamine synthetase (GS, E.C.6.3.1.2) is a key enzyme in ammonia assimilation either in plants or in gram-negative microorganisms. It plays an important role in the efficient utilization of nitrogen sources and nitrogen metabolism in organisms. With the development of modern biotechnology, numerous studies on GS resisting abiotic stress performed in transgenic plants, such as drought, salt, nitrogen poor source and herbicide, developing transgenic plants with more advantages.In this research, a plant constitutive expression vector p2GS harbouring GS1 and GS2 under the control of Actl and Ubi promoters was constructed. The p2GS was introduced into "zhonghua 10" rice by Agrobacterium-mediated transfer method, and transgenic plants with resistance to Hygromycin and Phosphinothricin have been obtained. Results of PCR and Southern blot analysis showed the foreign gene have integrated into rice genome. The transcription of GS gene in the transformants was also clarified by Northern blot analysis.In our research, the transgenic rice plants with p2GS can tolerate 0.3% basta solution. The result shows transgenic rice plants obtain herbicide resistance. Hence, GS gene can serve as a selective gene of rice transformants replace of bar gene. Again, the transgenic rice plants can grow in the MS medium without nitrogen compounds added 0.7 mM (NH4)2SO4, and fresh weight of the transformants increased 0.5% comparing to the control rice plants. The result suggests that expression of p2GS confers the transgenic rice plants nitrogen-poor tolerance.