小花碱茅HKT2;1基因全长cDNA的克隆与生物信息学分析

Cloning and bio-infomatical analysis of the high-affinity K^+ transporter gene PutHKT2;1 from the halophyte Puccinellia tenuiflora

Na+是盐渍化土壤中主要的毒害离子,对植物生长发育和农业生产构成严重威胁。高亲和性K+转运蛋白HKT2;1在控制高等植物Na+吸收,增强K+的选择性,进而提高耐盐性方面发挥着重要作用。本研究以拒盐型牧草小花碱茅为材料,采用RT-PCR和RACE(rapid amplification of cDNA ends)方法克隆到HKT2;1基因,并命名为PutHKT2;1。该基因全长1 919bp,包含1个长1 638bp的开放阅读框(ORF),编码546个氨基酸,推测分子量为60.5kDa,等电点PI为9.07。与其他植物HKT2;1氨基酸序列同源性多在66%以上,核苷酸序列同源性都在75%以上。PutHKT2;1可能跨膜11次,二级结构分析表明,PutHKT2;1蛋白含有47.99%α-螺旋、5.13%β-转角、31.87%无规则卷曲和15.01%延伸链。PutHKT2;1基因全长cDNA的克隆及其生物信息学分析为进一步揭示小花碱茅拒盐的分子机制奠定了基础。

Saline soils are normally dominated by Na＋ which threatens plant growth and agricultural productivity.Increasingly research has focused on the functions of high-affinity K＋ transporter HKT2;1 in controlling Na＋ uptake,strengthening the selectivity of K＋ and thus enhancing salt tolerance.A putative high-affinity K＋ transporter gene PutHKT2;1 was isolated from the halophyte Puccinellia tenuiflora by RT-PCR and RACE methods and was used to investigate the sodium tolerance mechanism.The gene was 1 919 bp in total length with an open reading frame（ORF） of 1 638 bp encoding a 60.5 kDa protein with 546 amino acids and theoretical PI of 9.07.Sequence analysis suggested that the nucleotide sequence and the translated amino acid sequence shared over 75% and 66% of homology to the HKT2;1 gene sequences from other higher plants.The PutHKT2;1 protein might have 11 transmembrane segments.Secondary structure analysis indicated that the PutHKT2;1 contained a 47.99% α-helix,5.13% β-turns,31.87% random coils and 15.01% extended strand.Cloning the full length PutHKT2;1 gene and its bio-informatical analysis will be helpful to elucidate the salt tolerance mechanism of P.tenuiflora.