Genetic structure composed of additive QTL, epistatic QTL pairs and collective unmapped minor QTL conferring oil content and fatty acid components of soybeans

Abstract

The relative importance of various types of quantitative trait locus (QTL) conferring oil content and its fatty acid components in soybean seeds was assessed through testing a recombinant inbred line (RIL) population (derived from KF1 9 NN1138-2) in randomized blocks experiments in [2004][2005][2006]. The contents of oil and oleic, linoleic, linolenic, palmitic and stearic acids were determined with automatic Soxhlet extraction system and gas chromatography, respectively. Based on the established genetic linkage map with 834 markers, QTLNetwork2.0 was used to detect QTL under the genetic model composed of additive, additive 9 additive (epistasis), additive 9 year and epistasis 9 year effects. The contributions to the phenotypic variances of additive QTL and epistatic QTL pairs were 15.7% (3 QTL) and 10.8% (2 pairs) for oil content, 10.4% (3 QTL) and 10.3% (3 pairs) for oleic acid, 11.6% (3 QTL) and 8.5% (2 pairs) for linoleic acid, 28.5% (7 QTL) and 7.6% (3 pairs) for linolenic acid, 27.0% (6 QTL) and 16.6% (7 pairs) for palmitic acid and 29.7% (5 QTL) and 4.3% (1 pair) for stearic acid, respectively. Those of additive QTL by year interaction were small and no epistatic QTL pair by year interaction was found. Among the 27 additive QTL and 36 epistatic QTL (18 pairs), three are duplicated between the two QTL types. A large difference was found between the genotypic variance among RILs and the total variance of mapped QTL, which accounted for 52.9-74.8% of the genotypic variation, much larger than those of additive QTL and epistatic QTL pairs. This part of variance was recognized as that due to a collection of unmapped minor QTL, like polygenes in biometrical genetics, and was designated as collective unmapped minor QTL. The results challenge the breeders for how to pyramid different types of QTL. In addition, the present study supports the mapping strategy of a full model scanning followed by verification with other procedures corresponding to the first results.

Cell Wall Composition and Underlying QTL in an F1 Pseudo-Testcross Population of Switchgrass

“…4 (continued) The importance of epistatic effect QTL has been documented for various traits in rice [44][45][46][47][48], wheat [49][50][51], and soybean [52], demonstrating that both main effect and epistatic QTL are underlying various quantitative traits in plants. The negative correlation of lignin content and sugar release observed in this population suggests that some segregants or natural variants with reasonably low lignin content and above average sugar release may be identified through selection.…”

Quantitative trait loci (QTLs) analysis of palm oil fatty acid composition in an interspecific pseudo-backcross from Elaeis oleifera (H.B.K.) Cortés and oil palm (Elaeis guineensis Jacq.)

“…(Wilson et al 2001;Monteros et al 2008;Ha et al 2010;Li et al 2011;Chen et al 2012) and olive (Olea europaea L.) (Poghosyan et al 1999;Hernández et al 2005;Banilas et al 2011). With respect to genes involved in the fatty acid biosynthesis in oil palm, Nakkaew et al (2008) identified and cloned the gene of biotin carboxylase (accD) from E. guineensis which is involved in the first step of the fatty acid synthesis.…”

Genotyping-by-Sequencing-Based Investigation of the Genetic Architecture Responsible for a ∼Sevenfold Increase in Soybean Seed Stearic Acid

“…Though all the QTL were of minor effect, we saw some positional overlap with published QTL for seed linolenic acid. Li et al (2011) identified an association between Satt537 and seed linolenic acid content on chromosome 2 at nearly the same map position as q.2n (within 5 cM). In the same study, a QTL was identified on chromosome 4, however it was not in the same region as q.4n .…”

“…The two QTL identified on chromosome 2 accounted for 13.75 and 7.86% of the variation in seed stearic acid content. QTL associated with stearic acid have been previously reported on chromosome 2 within 5 cM of q.2.1s (Li et al 2011; Xie et al 2011). On chromosome 4, the 194D allele contributed to elevated stearic acid.…”