Improvement of nitrogen use efficiency in maize using molecular and physiological approaches

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The germination percentages for all maize (10 inbred lines) used under N+ or N- nutritional regimes was determined. Significant germination differences for inbred 6, 8 and 10 were indicated, while the other differences were non-significant. A large amount of phenotypic diversity is observed across maize lines, attributed mostly to significant differences in genome structural and gene presence/absence variation. Inbred line number 10 seems to be the most homogeneous genotype among the lines tested. This line showed the most normal germination and growth rate under (N+) and (N-) regimes. During the second season, these two lines (10 and 8) showed normal germination and growth rate under (N+) and (N-) regimes. Both inbred lines were significant for leaf Nitrogen content while, line 10 showed more significant difference for leaf Nitrogen content under (N+) and (N-) nutritional regimes. In order to characterize some genes related to NUE, the differential display PCR was applied for leaf extract samples of inbred lines 8 and 10 at three different developmental stages 5, 7 and 10 weeks grown under N+ (T1, T2, and T3) and N- (C1, C2 and C3) regimes, respectively. Some of the specific NUE amplified fragments were expressed in two developmental stages. Therefore, from the total of 39 amplified fragments, the sum of 31 expressed genes was identified through our present work. The phylogenetic analysis showed that sequences of glutamine synthetase gene are grouped among two clusters.