Fatty acid composition of oil from soybean seeds grown at extreme temperatures

Abstract

Temperature during seed development is known to influence the level of the various fatty acids in soybean [Glycine max (L.) Merr.] oil. In order to determine the range of values that can be obtained for each fatty acid, five lines (A5, C1640, N78-2245, PI 123440 and PI 361088B) known to possess low linolenic acid (18:3) levels, one line (A6) known to possess a high stearic acid (18:0) level, and two cultivars (Century and Maple Arrow) were grown at 40/30, 28/22, and 15/12°C day/night. At 40/30°C, high oleic acid (18:1), low linoleic acid (18:2), and low linolenic acid levels were obtained that were beyond the range of levels reported for the soybean germplasm. The linolenic acid levels for A5, C1640 and N78-2245 grown at 40/30°C were below 2.0%, and are the lowest values reported for soybean oil. A6 displayed a high level of stearic acid at 28/22 and 40/30°C but displayed a relatively low level at 15/12°C. This indicates that temperature may affect the expression of thefas ^a allele, which is responsible for high stearic acid levels in A6. The linolenic acid levels of PI 361088B and C1640, both possessing thefan allele, were the lowest for all lines grown at 15/12°C. Therefore, thefan allele is an appropriate source for the development of low linolenic acid lines adapted to cool areas.