Tocopherols in breeding lines and effects of planting location, fatty acid composition, and temperature during development |
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Authors: | David Dolde Chris Vlahakis Jan Hazebroek |
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Affiliation: | (1) Pioneer Hi-Bred International, Inc., 7300 N.W. 62nd Ave., P.O. Box 1004, 50131-1004 Johnston, IA |
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Abstract: | As the use of tocopherols as natural antioxidants increases, it is economically and agronomically important to determine the
range, composition, and factors that affect their levels in oilseed crops, a major commercial source. In this study, tocopherols
were quantified from seeds of wheat, sunflower, canola, and soybean. The breeding lines analyzed possessed a broad range of
economically important phenotypic traits such as disease or herbicide resistance, improved yield and agronomic characteristics,
and altered storage oil fatty acid composition. Complete separation of all four native tocopherols was achieved using normal-phase
high-performance liquid chromatography with ultraviolet detection. Total tocopherol concentration among wheat germ oil samples
ranged from 1947 to 4082 μg g−1. Total tocopherol concentration ranges varied from 534 to 1858 μg g−1 in sunflower, 504 to 687 μg g−1 in canola, and 1205 to 2195 μg g−1 among the soybean oils surveyed. Although the composition of tocopherols varied substantially among crops, composition was
stable within each crop. Total tocopherol concentration and the percentage linolenic acid were correlated positively in soybean
oils with modified and unmodified fatty acid compositions. Tocopherol concentration and degree of unsaturation were not correlated
in sunflower or canola seeds with genetically altered fatty acid composition. These findings suggest that breeding for altered
storage oil fatty acid composition did not negatively impact tocopherol concentrations in sunflower and canola as they apparently
did in soybeans. When 12 soybean breeding lines were grown at each of five locations, significant correlations were observed
among planting location, breeding line, tocopherol concentration, and fatty acid composition. Analysis of seeds that matured
under three different controlled temperature regimes suggests that the relationship between tocopherol concentration level
and unsaturated fatty acids in commodity (not genetically modified for fatty acid composition) oil types is due to temperature
effects on the biosynthesis of both compounds. |
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Keywords: | Fatty acid composition fatty acid modification genetic effects location effects temperature effects tocopherol vegetable oil |
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