Genetic variability of principal isoflavones in red clover
Isoflavones, known for their health benefits, are abundant in red clover (Trifolium pratense L.). Total isoflavone concentrations can be 30 times that of soybean, indicating that red clover is a good source of nutraceutical and functional food ingredients. In this study, tissue samples of 13 red clover cultivars were taken at two growth stages (late-bud stage and late-flowering stage) to determine the concentration of individual isoflavones using HPLC. Individual isoflavone concentrations and total isoflavone concentration differed significantly according to red clover cultivar. We found significant genetic variability for total isoflavone concentration and individual isoflavone concentrations; these differences were not related to ploidy level (diploid vs. tetraploid). Broad-sense heritability (H = genetic variance/total variance) ranged from 0 to 83% and was influenced by isoflavone type and sampling date. The results of this study suggest that there is significant genetic variability for isoflavone concentrations among currently available red clover cultivars. Key words: Trifolium pratense L., biochanin A, formononetin, growing stages, broad-sense heritability