大豆2-甲基-6-植基-1,4-苯醌甲基转移酶基因(Gm VTE3)的克隆及对转基因烟草种子中生育酚组成的影响

Cloning of Glycine Max 2-Methyl-6-Phytyl-1,4-Benzoquinol Methyltransferase (Gm VTE3) Gene and Engineering Vitamin E Content in Seed of Transgenic Tobacoo

【目的】克隆大豆2-甲基-6-植基-1,4-苯醌甲基转移酶基因(GmVTE3),研究其在烟草中过量表达对转基因烟草种子中生育酚(维生素E)组分的影响。【方法】利用EST拼接和RT-PCR技术,从大豆中分离了大豆2-甲基-6-植基-1,4-苯醌甲基转移酶(VTE3)的全长cDNA序列,通过烟草转化研究过量表达VTE3对转基因植株维生素E组分的影响。【结果】GmVTE3全长1026bp,编码342个氨基酸,与其它物种的VTE3氨基酸同源性很高,在烟草中过量表达该基因使烟草种子中γ-生育酚与δ-生育酚的比值最高增加2倍。【结论】首次克隆了大豆2-甲基-6-植基-1,4-苯醌甲基转移酶基因GmVTE3,它能够催化烟草植株中2-甲基-6-植基-1,4-苯醌(MPBQ)的甲基化,从而改变烟草种子中生育酚的组成成分。说明可以利用克隆的GmVTE3来改变植物种子中生育酚的组成和提高α-生育酚的含量。

【Objective】 VTE3 is a key enzyme in vitamin E pathway. A VTE3 like gene （Gm VTE3） was cloned from soybean,and the expression of Gm VTE3 in tobacco and effect on tocopherol composition of seed were studied. 【Method】 A putative VTE3 was cloned and characterized from soybean via EST sequence splicing and RT-PCR,the expression was analyzed and the effect of overexpression of Gm VTE3 on tocopherol composition of seed was studied in tobacco.【Result】The full-length cDNA of Gm VTE3 is 1 026 bp,which encodes a polypeptide of 342 amino acids. The amino acid homologies of MPBQ MT among different species share higher similarities. Expression of Gm VTE3 in transgenic tobacco increased the ratio of γ-tocopherol and δ-tocopherol by two times compared with the control. 【Conclusion】 Gm VTE3 is the first VTE3 cloned in soybean and may catalyze the methylation of 2-methyl-6-phytyl-1,4 benzoquinol in tobacco plant and alter seed tocopherol composition. These findings demonstrate that the gene identified in Glycine max may be used to alter the tocopherol composition of other commercial seed oils.