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Title: WARM TEMPERATURES OR DROUGHT DURING SEED MATURATION INCREASE ALPHA- TOCOPHEROL IN SEEDS OF SOYBEAN (GLYCINE MAX [L.] MERR.)

Author
item Britz, Steven
item Kremer, Diane

Submitted to: Journal of Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2002
Publication Date: 11/8/2002
Citation: Britz, S.J., Kremer, D.F. 2002. Warm temperatures or drought during seed maturation increase alpha-tocopherol in seeds of soybean (glycine max [l.] merr.). Journal of Agricultural and Food Chemistry. 50:6058-6063.

Interpretive Summary: Vitamin E comes from tocopherols, a family of fat-soluble antioxidants. Some recent recommendations calling for increases in vitamin E consumption will require supplements because vegetable oil, the primary dietary source of vitamin E, is low in alpha-tocopherol, the tocopherol with the highest vitamin E activity. ARS scientists have found that warmer temperatures during seed maturation increase alpha-tocopherol in soybean seeds by 2-3 fold. Soybeans are the largest source of vegetable oil in the American diet. It may be possible to breed for soybeans with an altered response to temperature and increased alpha-tocopherol under field conditions, thus diminishing the need for supplements. Since the response is very sensitive to temperature, it is also likely that differences in weather or climate affect tocopherols in some current soybean lines. This information will be useful to soybean breeders, to scientists studying nutrition, plant biology, or environment and to policy makers assessing the potential impact of global change.

Technical Abstract: Soybean seeds are an important source of dietary tocopherols, but like seeds of other dicotyledonous plants, they contain relatively little alpha-tocopherol, the form with the greatest vitamin E activity. To evaluate potential effects of environmental stress during seed maturation on tocopherols, three soybean lines were raised in greenhouses at nominal average temperatures of 23 deg. C or 28 deg. C during seed fill, with or without simultaneous drought (soil moisture at 10-25 percent of capacity). Total tocopherols increased slightly in response to drought in two of the three lines. All three lines responded to elevated temperature and, to a lesser extent, drought with large (up to 2-3 fold) increases in alpha- tocopherol and with corresponding decreases in delta-tocopherol and gamma- tocopherol. The results suggest that weather or climate can have significant effects on seed tocopherols. It may be possible to breed for elevated alpha-tocopherols by selecting for altered plant response to temperature.