毛果杨基因PtNRT2.7的功能初步鉴定与分析

本研究从毛果杨基因组中克隆一个NRT2家族的新基因PtNRT2.7。生物信息学分析显示,其编码的蛋白不存在信号肽及切割位点,属于非分泌蛋白;具有11个跨膜结构域,亲水区与输水区交替分布,主要分布于细胞膜,而且该基因的亚细胞定位分析显示该蛋白定位于细胞膜,综合以上结果可判断此蛋白为膜蛋白。对其在毛果杨的表达特征分析显示,PtNRT2.7基因主要在叶片中表达,其中成熟叶中的表达量最高;PtNRT2.7基因受硝酸盐诱导并在1 h时达到表达峰值;SA、JA、GA或IAA激素处理可诱导PtNRT2.7基因表达,而在Eth、ABA或NaCl处理下该基因的表达受抑制。利用农杆菌花序侵染法转化野生型拟南芥和突变体(nrt2.7),显示在KNO3浓度大于0.1 mmol/L时,PtNRT2.7过表达株系相比较拟南芥野生型和突变体株系促进了根的生长,而atnrt2.7突变体在KNO3浓度大于1 mmol/L的条件下抑制了根的生长,且PtNRT2.7过表达atnrt2.7突变体株系可恢复正常生长。研究结果表明,PtNRT2.7可以由硝酸盐和激素诱导并增强植物根系的生长,提高氮素的吸收利用。 

Functional identification and analysis of PtNRT2 7 gene from Populus trichocarpa

In present study, we successfully isolated a gene from NRT2 family named PtNRT2. 7. Bioinformatic analyses showed that PtNRT2. 7 had 11 transmembrane regions, and hydrophobic regions and hydrophilic regions are distributed alternately on cell membrane without signal peptide. Subcellular localization analysis showed that the PtNRT2. 7-GFP fusion protein is distributed on cell membrane. According to above findings, it belongs to a membrane protein. The expression features of Populus trichocarpa showed that PtNRT2. 7 expresses in leaves, with the highest expression in mature leaves; the highest expression appears at 1 h under the nitrate stress;under the stress of SA/JA/GA/IAA, the expression of PtNRT2. 7 is up-regulated in both above-and underground parts;under the stress of Eth/ABA/NaCl, the expression of PtNRT2. 7 is down-regulated. The expression vector was constructed and transformed into Arabidopsis thaliana wild type ( Col-0 ) and atnrt2. 7 mutant using floral dip method. The stress of different concentrations of KNO3 showed that, when the concentration of KNO3 is more than 0. 1 mmol/L, the root enlongation of overexpression lines is longer than others; the mutant lines are inhibited when the concentration is more than 1 mmol/L but the complementary lines can remove the inhibition. The result showed that hormones and NO3- can induce PtNRT2. 7, enhance the root growth and promote the absorption of nitrogen.