Fine mapping of a major flowering time QTL on soybean chromosome 6 combining linkage and association analysis

Flowering time is a key trait in the plant life cycle and an important selection criterion for soybean. Here, we combine the advantages of genome-wide association and linkage mapping to identify and fine map quantitative trait loci (QTLs) associated with flowering time. Linkage mapping was performed using 152 recombinant inbred lines and a major QTL, qFT6, affecting flowering time was found on chromosome 6. To refine the qFT6, the 192 natural accessions were genotyped using eight new simple sequence repeats and 10 single nucleotide polymorphisms markers covering the qFT6 region Haplotype analysis showed that the haplotype between markers BARC-014947-01929 and Satt365 could explain more phenotypic variation (26.5 %) than any other combination of markers. These results suggested that the target flowering time gene was located in ~300 kb between BARC-014947-01929 and Satt365, including three predicted genes. High-resolution map in qFT6 region will be useful not only for marker-assisted selection of flowering time but also for further positional cloning of the target gene. These results indicate that combining association and linkage mapping provides an efficient approach for fine mapping of soybean genes.