concentration was low, so investigation on NRT2 became the focus of the study on plant nitrogen absorption and application (Wu and Zhao, 2010). Gene that was related with ammonium-nitrogen was a family member of AMT, and played an important role in plants absorbing nitrogen from soil. Glutamine synthetase gene and glutamate synthase gene expression were influenced by different environmental factors, and amino acid synthesis required coupling of those two and involvement of various amino acid aminotransferases (Wang, 2011). Glutamate synthase gene mainly adjusted proline synthesis in phloem as a main metabolite for N source during drought stress. The excess expression of this gene in plants can improve the content of soluble protein, total amino acid, and total N in leaves, which are beneficial for plant stress tolerance (Cai et al., 2009). QTL gene mapping showed that GS on N accumulation, transformation and nitrogen use efficiency (NUE) was co-adjusted by many representative gene components. GS gene played an important role in N allocation and transportation in many rhizomatous grasses (Swarbreck et al., 2011). Two glutamine synthetase genes and three aquaporin (TIPs) genes were isolated from ryegrass (Lolium perenne L.), where the glutamine synthetase gene was to control N absorption and transportation, and aquaporin (TIPs) gene was to influence N transportation through tonoplast into vacuole to store N (Nord-Larsen et al., 2009).