Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2007
Publication Date: 9/28/2007
Citation: Rasolohery, C.A., Berger, M., Lygin, A.V., Lozovaya, V.V., Nelson, R.L., Dayde, J. 2007. Effect of temperature and water availability during late maturation of the soybean seed on germ and cotyledon isoflavone content and composition. Journal of the Science of Food and Agriculture. 88:218-228. Interpretive Summary: Isoflavones are bioactive compounds in soybean seeds which have been associated with many positive human health effects. Seed isoflavone content varies greatly among varieties and between parts of the soybean seed and is influenced by the environment in which the seed grows. Our objective was to quantify the environmental and genetic effects on isoflavone concentrations in the germ and the cotyledons, two seed parts. By growing plants of five different varieties under controlled conditions in the greenhouse, we found that isoflavone content in the cotyledons can be up to 6 times higher if seeds develop in cool temperature rather than very warm temperatures but the change in the germ was less than a two-fold variation. In both seed parts, the isoflavone concentrations were highly dependent on the variety. These results show that isoflavone content in cotyledon and germ are unrelated and it should be possible to independently manipulate these seed traits through plant breeding and crop management systems.
Technical Abstract: Soybean seeds contain high levels of isoflavones (genistein, daidzein, glycitein), which have been associated with many positive human health effects. Seed isoflavone content is strongly influenced by both environment and genotype. The isoflavone concentration and composition of the soybean seed germ is very different than the cotyledons. Little is known about the effect of environment and genotype on isoflavones in germs vs cotyledons. Our objective was to quantify the environmental and genetic effects on isoflavone concentrations in these two seed parts. To determine the effect of temperature and soil moisture status during soybean seed development on seed isoflavone concentration and composition, a set of two French three U.S. cultivars of similar maturity were grown in the greenhouse. At the R6 growth stage, plants were subjected to one of three night/day temperature regimes (13/23°, 18/28°, or 23/33° C) in either optimal or sub-optimal soil water conditions. In cotyledons, a 3 to 6 fold variation in total isoflavone content was observed between the high and low temperature treatments, whereas the germs contents had less than a two-fold variation. Soil water supply had less effect than temperature on the isoflavone contents and compositions. In both seed parts, the isoflavone concentrations were highly dependent on the cultivar. These results show that isoflavone content and composition in cotyledon and germ are unrelated and it should be possible to independently manipulate these seed traits through plant breeding and crop management systems.