Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2013
Publication Date: 1/31/2014
Citation: Smallwood, C.J., Nyinyi, C.N., Kopsell, D.A., Sams, C.E., West, D.R., Chen, P., Kantartzi, S.K., Cregan, P.B., Hyten, D.L., Pantalone, V.R. 2014. Detection and validation of quantitative trait loci for soybean isoflavones. Crop Science. 54:595-606. Interpretive Summary: The soybean seed contains the isoflavones genistein, daidzein, and glycitein. Numerous benefits associated with soybean isoflavones have been suggested including cancer prevention, reduced risk for coronary heart disease, reduced problems with diabetes and obesity, improved bone and cardiovascular health, and decreased menopausal symptoms. The objective of this research was to determine the positions of genes, also referred to as quantitative trait loci (QTL), that control the quantity of the three soybean isoflavones in the soybean seed. A total of 282 progeny from a cross of the soybean cultivars Essex and Williams 82 were planted at three field locations along with the parents and check cultivars. The isoflavone content of the seed harvested from these field experiments was analyzed using near infrared reflectance spectroscopy (NIRS). In addition, 1536 single nucleotide polymorphism (SNP) DNA markers were used to analyze each of the progeny and the parents. The combined analysis of the DNA marker data and the isoflavone data detected a total 21 genes/QTL: 7 for genistein, 5 for daidzein, 3 for glycitein and 6 for total isoflavones. The SNP DNA markers in close proximity to the QTL/genes in the 21 regions can be used by plant breeders and geneticists in marker assisted selection to identify soybean progeny with increased levels of the seed isoflavones.
Technical Abstract: Interest in soybean [Glycine max (L.) Merrill] isoflavones has increased in recent years due to numerous potential health benefits. Consequently, quantitative trait loci (QTL) detection for marker assisted breeding is being examined for potential genetic gains. This study sought to detect QTL for soybean isoflavones in a population of 274 recombinant inbred lines (RILs) derived from parental lines ‘Essex’ and ‘Williams 82’ that were subdivided and tested by maturity (early, mid, and late). The field tests were grown in three environments in 2009 (Knoxville, TN; Harrisburg, IL; and Stuttgart, AR). The population was genotyped with 1,536 single nucleotide polymorphism (SNP) markers, of which 480 were polymorphic. Isoflavone data for each replicate was analyzed with near infrared reflectance spectroscopy (NIRS), whose prediction equation was based on high performance liquid chromatography (HPLC). NIRS is much faster and less expensive than the HPLC method for isoflavone measurement. Each maturity test, containing 91 or 92 RILs, was analyzed separately for QTL. In total 21 QTL were detected: 7 for genistein (chromosomes 5, 6, 9, 9, 13, 17, and 19), 5 for daidzein (chromosomes 5, 6, 9, 13, and 19), 3 for glycitein (chromosomes 6, 9, and 20), and 6 for total isoflavones (chromosomes 5, 5, 6, 9, 13, and 19). Of these 21 QTL, 8 QTL had not been previously reported, while 13 QTL were validated from other studies. Utilization of these QTL could potentially lead to marker-assisted selection approaches for genetic gains for soybean isoflavones.