The Expression Pattern Analysis And Over-Expressed Effectionon Rice Growth/Nitrogen Accumulation Of Nitrate Transporter Gene OSNPF7.9 In Rice

Plants need a variety of nutrition elements in the whole life cycle, in all the necessary nutrients, nitrogen is limiting plant growth and the formation of the primary factor of production, at the same time it also has obvious effect on improving the product quality. Ammonium and nitrate is the main nitrogen for plants. Plant absorb nitrate via nitrate transporter, according to its different to nitrate transport efficiency, divided into high affinity nitrate transporters (also called NRT2s) and low affinity nitrate transporters (also called NRTls), Laren et al (2014) collectively renamed NRT1s and PTRs (Peptide transporter) as NPFs (Laren et al.,2014).Rice prefers to ammonium. However, some studies show that rice roots can secrete oxygen and own ventilation organization developed at the same time which can convert ammonium around the root into nitrate.We studied the function of OsNPF7.9 using semi-quantitative RT-PCR, q-PCR, over expression and fused GUS reporter gene to the promoter. And main results were listed as follows:1. Bio informatics analysis revealed OsNPF7.9 gene owns five exons, four introns and encoding 610 amino acids as OsNPF7.9 have 10-12 trans-membranes. OsNPF7.9 expresses the whole plant. Phylogenetic analysis showed that OsNPF7.9 is closed to AtNRT1.5 and AtNRT1.8 as well as OsNRT1.1. Motifs analysis in OsNPF7.9 promoters showed OsNPF7.9 promoters contain the motifs related to nitrogen, light, drought and hormones.2. By fusing the promoter to GUS reporter gene, using agrobacterium-mediated transgenic technology, OsNPF7.9 expressed nearly in all of organs of the whole rice plant, such as husk, anther, germination of embryo and radicle, leaf blade, culm and sheath, shoot-root junction, root stele, root hair.Based on RT-PCR and GUS fusion data showed the expression pattern of OsNPF7.9 was not affected by nitrogen forms and concentration.3. Using qPCR technology to study the effect of potassium and drought on OsNPF7.9 expression, OsNPF7.9 expressed in the underground was significantly suppressed while aboveground significantly increased under potassium depleted. Drought treatment with 5%(m/v) PEG showed that OsNPF7.9 in aboveground expression was significantly suppressed as well underground part; The expression ofOsNPF7.9 was induced by 10 μM IAA、50 μM ABA、1 μM T-transzeatin4. After 30 days normal hydroponics, the aboveground dry weight of over expression lines (OE4 and OE5) increased about 20.2% and 20.9% respectively. In addition, root/shoot ratio decreased about 13.1% and 14.2%respectivelyapart from the underground dry weight. Meanwhile the total nitrogen of shoot and root were obviously increased. Analysis of agronomy characters displayed that the length of leaf and spike increased apparently while seed setting rate and straw ratio decreased obviously. The total nitrogen of seeds, clever shell and flat shell increased significantly.