A putative lowaffinity nitrate transporter, OsNRT1.2 gene, was identified based on the rice genomic database and bioinformatics analysis. By Agrobacterium tumefaciens transformation with a Ubiquitin (Ubi) promoter, the gain of function of rice OsNRT1.2 was tested by overexpression in Wuyunjing 7. The OsNRT1.2 cDNA from Knowledgebased Oryza Molecular Biological Encyclopedia (KOME) database encoded 533 amino acids with a fulllength of 2178 bp and an open reading fragment (ORF) of 1732 bp. The expression pattern of OsNRT1.2 in Wuyunjing 7 was investigated and the results showed that its mRNA was only expressed in roots but not in shoots. And the overexpressed plants were generated by the transformation of pUbiOsNRT1.2 into Wuyunjing 7. Wild type (WT) and three T2 generation transgenic lines, named as OE1, OE2 and OE8, were used in the growth experiment at 0.2 and 5.0 mmol/L nitrate for 30 days and the plant height and root length were recorded every 10 days. The results showed that the plant height of WT and transgenic plants had no difference except OE8 line at 5.0 mmol/L NO3- , while the root length of transgenic lines significantly decreased at both 0.2 and 5.0 mmol/L nitrate. Nitrogen (N) content in shoots and roots was not different between WT and transgenic lines at 0.2 mmol/L NO3-. But at 5.0 mmol/L NO3-, compared with WT, the shoot nitrogen content of OE2 and OE8 except OE1 was increased and the root N content of all transgenic lines was significantly decreased. The rootshoot ratio of transgenic lines was significantly decreased at 0.2 and 5.0 mmol/L nitrate levels. The dry weight of transgenic lines was significantly increased by from 9.4% to 31.1% at 0.2 mmol/L nitrate and from 12.5% to 43.8% at 5.0 mmol/L nitrate. It indicated that OsNRT1.2 in Wuyunjing 7 might be involved in the N translocation from plant roots to shoots and therefore shoot biomass was increased.
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