High-resolution genetic maps of Lotus japonicus and L. burttii based on re-sequencing of recombinant inbred lines.

Recombinant inbred lines (RILs) derived from bi-parental populations are stable genetic resources, which are widely used for constructing genetic linkage maps. These genetic maps are essential for QTL mapping and can aid contig and scaffold anchoring in the final stages of genome assembly. In this study, two Lotus sp. RIL populations, Lotus japonicus MG-20 x Gifu and Gifu x L. burttii, were characterized by Illumina re-sequencing. Genotyping of 187 MG-20 x Gifu RILs at 87,140 marker positions and 96 Gifu x L. burttii RILs at 357,973 marker positions allowed us to accurately identify 1,929 recombination breakpoints in the MG-20 x Gifu RILs and 1,044 breakpoints in the Gifu x L. burttii population. The resulting high-density genetic maps now facilitate high-accuracy QTL mapping, identification of reference genome mis-assemblies, and characterization of structural variants.