Analysis Of Activities And Characterization Of The Gene Expression Of Key Nitrogen Metabolism Enzymes In Rice Genotype With Different N Use Efficiency

Application of nitrogen fertiliser is the most important agricultural measures in increasing paddy rice production. However, excessive nitrogen fertilizer reduced utilization efficiency of fertilizer, which brought some eco-environment of nitrogen pollution in the mean time. A fundamental way of improving nitrogen utilization efficiency on genotypic difference of crop is breeding new varieties of crops with higher yield of high nitrogen use efficiency out of the unity of quality (ie nitrogen efficiency cultivar). Therefore, the test has been done in 2008 and 2009 at proving ground in the Agricultural College of Yangzhou University for water planting experiments.3 N-efficient varieties and 3 N-inefficient varieties separately selected from 115 different varieties of the genotype rice (lines) in Jiangsu Province were studied at the activities of the key enzymes of nitrogen metabolism and characteristics of the gene expression,the main results are as follows:Glutamine Synthetase activity of N-efficiency cultivars was significantly higher than N-inefficient cultivars'in the critical stage of tillering, jointing, heading the biggest difference. The critical stage of tillering and jointing stage, two types of GS activity in different organs of rice varieties with higher nitrogen levels, but increased the impact of which on the blade stronger; stem and root GS activity showed high varieties of nitrogen and nitrogen level is significant. Heading stage, two types of GS activity in different organs of rice varieties with higher nitrogen levels, but increased in leaves and stem showed GS activity of N-inefficient cultivars affected by the ratio of nitrogen and high nitrogen levels were significantly varieties; root showed high nitrogen cultivars GS activity by nitrogen than for nitrogen-inefficient cultivars significantly.Nitrate Reductase activity in the whole growth period of the variation in the critical stage of tillers reached the maximum, began to decline in the jointing stage, heading stage and maturity to a minimum. Meanwhile, the two varieties of rice leaf nitrogen efficiency in the NR activity increased with increasing nitrogen levels. The critical stage of tillering and jointing stage, leaf NR activity in N-inefficient cultivars showed efficient than the N-type varieties affected by nitrogen level more significant. Different times in different organs of GOGAT activity increased with the increase of nitrogen and N-efficient varieties were higher than N-inefficient cultivars. The critical stage of tillering,nitrogen efficient varieties and N-inefficient significant difference between different organs. Jointing stage, nitrogen efficient varieties of GOGAT activity in leaf nitrogen levels to improve sensitivity more.Ammonium uptaking transporter gene (OsATM) that mainly expressed in root were gene OsAMT1.1, OsAMT1.2, OsAMT1.3. OsAMT1.1, OsAMT1.2 expression increased with the rise of nitrogen levels and N-efficient cultivars were higher than N-inefficient cultivars while OsAMT1.3 expression decreased with increasing levels of nitrogen and low nitrogen levels and high N levels in the cultivars than N-inefficient cultivars; ear, only genes carried OsAMT1.1 the expression, in addition to YangJing9538, nitrogen efficient varieties were higher than N-inefficient cultivars and temperature increased with the nitrogen levels.Encoding NO3- transporter gene (OsNRT2) expressed in various organs with the temperature increased nitrogen levels and were higher in the N-efficiency than in the N-inefficient cultivars of the three N levels.Encoding N transfer genes (GS), in leaves, the expression of genes OsGln1.2 had no significance between N-efficient varieties and N-inefficient varieties in three N levels;in stem, the gene OsGln2 were expressed higher in N-efficient than in N-inefficient varieties especial in the middle N level; in roots, gene OsGln1.1 nitrogen levels in the highest expression level,nitrogen efficient varieties than N-inefficient cultivars, gene OsGln1.2 as the temperature increased nitrogen levels and nitrogen efficient varieties than N-inefficient cultivars; in ear, the gene OsGln1.1 expression in the highest N levels and N-efficient varieties than N-inefficient varieties.Except gene OsGlt2 were not expressed in the four organs, encoding ammonium reabsorption genes (GOGAT) was mainly expressed in the roots and spike and the expression of nitrogen-effective was higher than N-inefficient.