Engineering vitamin E content: from Arabidopsis mutant to soy oil.
We report the identification and biotechnological utility of a plant gene encoding the tocopherol (vitamin E) biosynthetic enzyme 2-methyl-6-phytylbenzoquinol methyltransferase. This gene was identified by map-based cloning of the Arabidopsis mutation vitamin E pathway gene3-1 (vte3-1), which causes increased accumulation of delta-tocopherol and decreased gamma-tocopherol in the seed. Enzyme assays of recombinant protein supported the hypothesis that At-VTE3 encodes a 2-methyl-6-phytylbenzoquinol methyltransferase. Seed-specific expression of At-VTE3 in transgenic soybean reduced seed delta-tocopherol from 20 to 2%. These results confirm that At-VTE3 protein catalyzes the methylation of 2-methyl-6-phytylbenzoquinol in planta and show the utility of this gene in altering soybean tocopherol composition. When At-VTE3 was coexpressed with At-VTE4 (gamma-tocopherol methyltransferase) in soybean, the seed accumulated to >95% alpha-tocopherol, a dramatic change from the normal 10%, resulting in a greater than eightfold increase of alpha-tocopherol and an up to fivefold increase in seed vitamin E activity. These findings demonstrate the utility of a gene identified in Arabidopsis to alter the tocopherol composition of commercial seed oils, a result with both nutritional and food quality implications.
Van Eenennaam
Alison L
AL
Monsanto Company, Calgene Campus, Davis, California 95616, USA.
Lincoln
Kim
K
Durrett
Timothy P
TP
Valentin
Henry E
HE
Shewmaker
Christine K
CK
Thorne
Greg M
GM
Jiang
Jian
J
Baszis
Susan R
SR
Levering
Charlene K
CK
Aasen
Eric D
ED
Hao
Ming
M
Stein
Joshua C
JC
Norris
Susan R
SR
Last
Robert L
RL
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D030821:Plants, Genetically Modified; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013024:Soybean Oil / Q000378:metabolism*; D013025:Glycine max / Q000201:enzymology / Q000235:genetics; D024505:Tocopherols / Q000378:metabolism*; D014810:Vitamin E / Q000096:biosynthesis*
D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D014810:Vitamin E; D013024:Soybean Oil; C483729:2-methyl-6-phytylbenzoquinol methyltransferase, Arabidopsis; C447422:2-methyl-6-phytylbenzoquinone methyltransferase; D008780:Methyltransferases; C479072:delta-tocopherol; D024505:Tocopherols