白三叶TrMYB1R1全长克隆及转录表达分析

The clone of TrMYB1R1 from white clover and gene expression analysis

R1-MYB是MYB转录因子家族中的一亚类,可能参与植物非生物胁迫应答。通过RT-PCR和RACE技术,在白三叶(Trifolium repens)中成功克隆出一个MYB转录因子TrMYB1R1,基因全长1 403 bp,编码297个氨基酸残基。通过生物信息学分析,发现TrMYB1R1蛋白含有一个MYB结构域,属于MYB-related蛋白,保守域形成3个α-螺旋;亚细胞定位预测该蛋白可能位于细胞核中。同源进化分析结果显示TrMYB1R1蛋白和豆科植物MYB蛋白亲缘较近,蛋白进化符合植物进化分类。非生物胁迫和外源激素处理结果表明,该基因在白三叶根和叶中均受到诱导调节。在聚乙二醇(PEG)水分胁迫、镉胁迫、4℃冷处理及35℃高温处理下,白三叶TrMYB1R1表达受到抑制,且该基因对镉、冷及热处理响应强烈,对PEG处理响应较弱;而在NaCl胁迫处理下该基因受到诱导表达;同时,脱落酸(ABA)处理前期抑制TrMYB1R1表达,但细胞分裂素(CTK)显著诱导该基因表达。这些结果表明,该基因可能参与多种非生物胁迫应答并可能受激素调控,但对TrMYB1R1在白三叶中的功能及调控作用仍需进一步研究。

R1-MYB, a subtribe of the MYB family, may be involved in responses to abiotic stress in plants. In this study, a MYB transcription factor ‘TrMYB1R1’ was cloned from white clover (Trifolium repens) through RT-PCR and RACE. The complete sequence of TrMYB1R1 is 1 403 bp encoding 297 amino acids. Based on the analysis of information biology, TrMYB1R1 contains a MYB structural domain and its conservative domain could form 3 alpha-helixes, indicating that TrMYB1R1 is a MYB-related protein. TrMYB1R1 was located in the nucleus through prediction of the subcellular localization. The result of homologous evolution analysis showed that TrMYB1R1 has closer genetic relationships with MYB of Leguminosae. The TrMYB1R1 could be induced in leaves and roots of white clover under abiotic stress and phytohormone treatments. In detail, the expression of TrMYB1R1 was inhibited under water stress (PEG), cadmium, cold (4 °C), and heat (35 °C) stress. More importantly, cadmium and cold had stronger effects on the expression of TrMYB1R1 than PEG treatment. Differently, salt (NaCl) stress could significantly induce the increase in the expression of TrMYB1R1. For the phytohormone treatments, abscisic acid (ABA) inhibited the expression of TrMYB1R1, whereas cytomin (CTK) induced its expression. All of these results indicated that TrMYB1R1 could be involved in responses to abiotic stress and phytohormones, but the function of TrMYB1R1 still requires further investigation in white clover.