Validation and Detection of Quantitative Trait Loci for Soybean Isoflavones.

Interest in soybean [Glycine max (L.) Merrill] isoflavones has increased in recent years due to numerous potential health benefits. Analytical measurement methods for soybean isoflavones can be time consuming and costly. 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 three different maturity tests (early, mid, and late) in a population of 274 recombinant inbred lines (RILs) derived from parental lines ‘Essex’ and ‘Williams 82’. 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. Phenotypic data for each replicate was collected with near infrared reflectance spectroscopy (NIRS). NIRS is much faster and less expensive than the more commonly used high performance liquid chromatography (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. The utilization of these QTL could potentially lead to marker-assisted selection approaches for genetic gains for soybean isoflavones.