大豆TRK-HKT家族基因结构及逆境胁迫响应机制

植物TRK-HKT家族基因广泛介导植物Na+/K+运输,参与植物耐逆境胁迫调控。本研究以6个大豆钾利用效率差异品种为材料,利用in silico技术克隆到4个大豆TRK-HKT家族成员(Gm HKT1;1、Gm HKT1;2、Gm HKT1;3和Gm HKT1;4),采用q RT-PCR技术解析这些基因在低钾及逆境胁迫下的表达机制。结果表明,Gm HKT1;2在大豆幼苗根中对低钾胁迫的响应明显高于其他3个基因,且钾高效大豆品种这种响应更明显;同时Gm HKT1;2对不同逆境胁迫(低温、干旱、高盐和ABA)也有较强的响应。蛋白结构分析表明,仅Gm HKT1;2具有4个MPM结构域,4个保守的氨基酸残基空间上形成一个"漏斗样"结构,充当K+/Na+转运通道,通过邻近的ATP结合结构域,为K+/Na+转运提供能量。基因结构分析显示,这些基因均含3个外显子和2个内含子,不同基因间的第一个外显子和内含子片段大小差异显著,导致各基因的基因组DNA(g DNA)大小各异。启动子分析揭示,大豆TRK-HKT家族成员包含参与种子功能定位和各种激素及逆境胁迫应激反应的重要顺式作用元件;进化上该家族基因位于第一进化分支,含保守的Ser–Gly–Gly–Gly基序。

Structural Characterization and Abiotic Stress Response of Soybean TRK-HKT Family Genes

Plant TRK-HKT family genes are involved in Na+/K+ transportation and regulation to abiotic stresses. We used six soybean varieties with different potassium use efficiencies (PUE) as materials, cloned four soybean TRK-HKT family genes (GmHKT1;1, GmHKT1;2, GmHKT1;3, and GmHKT1;4) via in silico, and explored the genes structure and expression under low potassium treatment and abiotic stresses with qRT-PCR technique. The results showed that the expression level of GmHKT1;2 was higher than those of the other three members in the roots of soybean seedlings under low potassium stress, which was more obvious in the roots of the soybean varieties with high PUE. Meanwhile, GmHKT1;2 showed high response to various abiotic stresses (chilling, drought, high salinity, and ABA). Protein structure prediction showed that only GmHKT1;2 contains four MPM domains and a "funnel-like" structure of four conserved amino acid residues spatially, which acted as K+/Na+ transport channel and provided energy for transportation, together with the adjacent ATP binding domain. Analysis on gene structure indicated that there are three exons and two introns in all four members with a significant difference in the size of exon I and intron I, resulting in the genomic DNA (gDNA) difference in lenghth of the different GmHKT genes. Promoter analysis revealed that upstream promoter elements of soybean TRK-HKT family genes contained important cis-acting regulatory elements involved in the functional target to seed-specific expression, and response to hormone and diverse abiotic stresses. In evolution, soybean TRK-HKT family genes belonged to clade I with conserved Ser–Gly–Gly–Gly motif.