林烟草钾离子通道基因NKT6的克隆与表达定位分析

Shaker家族钾离子通道在植物钾的吸收转运及其他生命过程中发挥重要作用。本研究利用同源克隆的策略从林烟草中获得一个Shaker家族钾离子通道基因，命名为NKT6 (GenBank登录号为KC310448)。该基因cDNA序列全长2 317 bp，编码由681个氨基酸组成的蛋白，该蛋白与Shaker家族其他成员具有较高同源性。NKT6基因组CDS序列共含有11个外显子、10个内含子。系统进化树分析表明，NKT6蛋白是Shaker家族Group II的成员之一。荧光定量PCR分析发现，NKT6的表达量在林烟草的茎和腋芽中最高，在萼片、叶、花中其次，在根中最低。亚细胞定位结果表明，NKT6主要定位于细胞膜和核膜附近的内质网上。干旱与外源ABA胁迫处理下，NKT6的表达量均呈下降趋势。推测NKT6可能在林烟草气孔开放中发挥作用。

Molecular Cloning and Expression Analysis of Potassium Channel Gene NKT6 in Nicotiana sylvestris

Shaker family potassium channels play a crucial role in absorption and transportation of potassium in plants. A new potassium channel gene, designated as NKT6 (GenBank accession number KC310448), was isolated from N. sylvestris using homologous cloning strategy. The full length sequence of NKT6 cDNA was 2137 bp. The deduced protein sequence contained 618 amid acids and exhibited high homology with Shaker family potassium channels. The genomic sequence of NKT6 contained 11 exons and 10 introns. The phylogenetic tree showed that NKT6 belonged to Group II of Shaker family. Real-time quantitative PCR assay indicated that the expression level of NKT6 in stem was the highest at full-bloom stage of Nicotiana sylvestris. Subcellular localization assay showed NKT6 was localized on plasma membrane and endoplasmic reticulum of tobacco epidermal cells. The expression level of NKT6 declined under drought and ABA treatment. These results demonstrated that NKT6 might play a role in stomatal movement.