Identification of quantitative trait loci associated with soyasaponin I concentration in soybean seed

Key message Significant QTL for soyasaponin I, as the major component of the soyasaponin B, have been identified using an RIL soybean population, which could facilitate the development of functional food soybean cultivars. Soyasaponin B forms that are naturally found in soybean (Glycine max [L.] Merr.) seed, have been of interest to the food industry because of their functional food properties. The predominant form soyasaponin B is soyasaponin I. While some of the genes in the biosynthesis of soyasaponins have been characterized, the underlying genetics of soyasaponins as a quantitative trait is still poorly understood. The objective of this study was to identify quantitative trait loci (QTL) associated with the accumulation of soyasaponin I using a genetic mapping population. The population consisting of 186 F-4:7 recombinant inbred lines derived from the cross of 'OAC Glencoe' and 'OAC Wallace' was grown in two Southern Ontario locations in 2015 and 2016. The concentration of soyasaponin I was determined using high-performance liquid chromatography. Putative QTL associated with the accumulation of soyasaponin I were identified through simple interval mapping and composite interval mapping on chromosomes 10 and 16, which explained up to 11% of the total phenotypic variation per QTL for the trait. A significant positive correlation was observed between soyasaponin I and seed protein concentration in the mapping population, which may be advantageous for the development of soybean lines with improved soyasaponin I profiles. QTL identified in this study may facilitate marker-assisted selection for the development of food-grade soybean lines with improved functional properties.