Abstract:

【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.

Key words: soybean, 2-methyl-6-phytyl-1, 4-benzoquinol methyltransferase (VTE3), vitamin E, transgenic tobacco