Identification of quantitative trait loci and candidate genes controlling the tocopherol synthesis pathway in soybean (Glycine max)

A recombinant inbred line (RIL) population was used to identify quantitative trait loci (QTLs) and their candidate genes controlling the tocopherol (Toc) synthesis pathway. The RIL population was cultivated in field conditions in 3 years. A genetic map constructed using 1624 DNA markers was used for QTL analysis. We identified 22 QTLs for seed tocopherol contents and their ratios, of which two QTL clusters on chromosomes (Chr) 9 and 14 exerted consistent large effects on tocopherol composition across the 3 years. The QTL cluster localized on Chr 9 might correspond to gamma-TMT3, which controls the conversion of gamma-Toc into alpha-Toc. The QTL cluster localized on Chr 14 was novel, which might regulate the conversion of MPBQ (a precursor of delta-Toc) into DMPBQ (the precursor of gamma-Toc). The effect of the QTL cluster on Chr 14 was validated in a pair of near isogenic lines, and its candidate gene was mined. The identified QTLs and their candidate genes might be used in breeding programmes to improve alpha-Toc content in soybean seeds.

Automated summary

A RIL population was cultivated in field conditions for 3 years to identify QTLs and their candidate genes controlling the tocopherol synthesis pathway using a genetic map with 1624 DNA markers. 22 QTLs for seed tocopherol contents and their ratios were identified, with two QTL clusters on Chr 9 and 14 having consistent large effects on tocopherol composition across the 3 years. The QTL cluster on Chr 9 might correspond to gamma-TMT3, which controls the conversion of gamma-Toc into alpha-Toc, while the QTL cluster on Chr 14 could regulate the conversion of MPBQ into DMPBQ.