白桦BpGT14基因表达模式及对非生物胁迫诱导的响应

为了揭示BpGT14基因的分子结构特征,明确糖基转移酶BpGT14基因的表达模式及其对非生物胁迫的响应机制,初步探索其在白桦生长发育中的功能,在克隆白桦GT14基因全长序列的基础上,利用生物信息学对其理化性质进行了分析,应用实时荧光定量PCR技术分析BpGT14基因在野生白桦植株雄花序、木质部、韧皮部及叶片4个不同部位不同月份的表达差异; 同时,选用白桦茎段悬浮细胞进行了水杨酸(SA)、盐胁迫(NaCl)、重金属镉(CdCl₂)及4℃低温非生物胁迫处理,检测目的基因对逆境的响应情况。研究结果表明,BpGT14基因开放阅读框为1 302 bp,编码433个氨基酸。分析其氨基酸序列发现,该蛋白含有乙酰氨基葡糖转移酶结构域,属于14家族的重要结构域。该蛋白与其他物种GT14蛋白比对分析表明,这些蛋白在100—350氨基酸区域内保守性较高,而且该基因与毛果杨的GT14家族基因同源性高达79%。不同部位不同月份的表达模式分析结果表明,BpGT14基因的表达具有部位及时间特异性,其各部位表达量均与月份相关,同时发现其在木质部、韧皮部及叶片中的表达量较高,而在雄花序中表达量较低。非生物胁迫处理结果显示,BpGT14基因对不同处理均产生响应,但其响应模式不尽相同:SA、CdCl₂及低温处理结果显示,处理初期(6 h)目的基因上调表达,6 h处理时分别达到了对照组的51.2、48.9及3.3倍,24 h后相对表达量与对照组相比均下调,只有低温处理在96 h恢复上调表达; NaCl处理使白桦BpGT14基因的表达量全部呈现下调趋势,24 h处理后,BpGT14基因表达量下调明显,24 h后比对照组降低了93.7%。

The expression patterns of BpGT14 gene in Betula platypylla Suk. and the response to biotic stress

Birch(Betula platypylla Suk.)GT14 gene sequence, named BpGT14 gene(JQ409354)have been cloned in this study. Bioinformatics was used to analyze its physical and chemical properties. The expression of BpGT14 gene in xylem, phloem, leaves and male inflorescence of wild birch was analyzed through real-time PCR. At the same time, we had treated suspension cells of birch stems with salicylic acid(SA), salt stress(NaCl), cadmium(CdCl₂)and 4 ℃ to determine the stress response of BpGT14. Research indicated that the gene was 1 302 bp, encoding 433 amino acids. Protein analysis showed that the BpGT14 gene contained important domain of acetyl glucosaminyl transferase which belongs to a glycosyltransferase 14 family. The GT14 protein we selected from different species showed highly conserved amino acid sequence in the 100-350 region and the identity of BpGT14 and Populus trichocarpa GT14 was up to 79%. BpGT14 gene real-time quantitative PCR results showed that the gene expression had specificity in different months and parts. Meanwhile, the results showed that the expression levels of BpGT14 gene was higher in xylem, phloem and leaves than that in male inflorescence. The results of abiotic stress treatment showed that BpGT14 gene was respond to abiotic stress, but its response pattern was different. The results of SA,CdCl₂ and 4 ℃ treatments showed that early treatment increased the expression of the target gene. After 6 h treatment, the expression of BpGT14 gene was 51.2, 48.9 and 3.3 times compared with the control group, but then the relative expression levels were lower compared with the control group except the 4℃ at 96 h. NaCl treatment had been showing downward trend and reduced by 93.7% compared with control in 24 h. This study was to reveal the molecular structure of BpGT14, figure out the expression patterns of BpGT14 and the response to biotic stress and explore the function of BpGT14 in birch growth and development. It provides the basis and inspiration for the research of other woody plants.