Abstract
Heading date is a critical stage in the growth and development of oats. The objectives of this study were to identify DNA markers associated with quantitative trait loci (QTL) affecting heading date in hexaploid oat, and to locate and characterize heading date QTL by comparative analysis using an oat reference genome. Genetic linkage maps were constructed using single nucleotide polymorphism (SNP) markers in RIL lines from oat populations FL0206B-S-B-S1 × UFRGS 078030-1 and URS Taura × Leggett. Days to heading were collected in field trials, and QTLs for heading date were identified in several genomic regions of the two maps. Oat loci with the most significant additive effects were associated with linkage groups Mrg02, Mrg06, and Mrg05 in the FL0206B-S-B-S1 × UFRGS 078030-1 population and with Mrg12, Mrg24, and Mrg11 in the URS Taura × Leggett population. Major QTLs affecting heading date were mapped to locations consistent with known QTLs and candidate genes that play critical roles in regulating flowering. These genes include Hd3a and FT, which are orthologs of the Vrn3 gene and integrate the vernalization and photoperiod response pathways. The gene PRR37 is an ortholog of Ppd1, the main gene determining photoperiod sensitivity in wheat and barley. The COL13 and GI genes are involved in the regulation of flowering by photoperiod. In addition, novel QTLs were identified that are valuable for molecular selection in oat breeding programs aimed at developing new and improved oat cultivars adapted to specific growing conditions.