Two loci on chromosome 5H determine low-temperature tolerance in a Nure (winter) × Tremois (spring) barley map.

Barley (Hordeum vulgare subsp. vulgare) is an economically important diploid model for the Triticeae; and a better understanding of low-temperature tolerance mechanisms could significantly improve the yield of fallsown cereals. We developed a new resource for genetic analysis of winter hardiness-related traits, the ‘Nure’ x ‘Tremois’ linkage map, based on a doubled-haploid population that is segregating for low-temperature tolerance and vernalization requirement. Three measures oflow-temperature tolerance and one measure of vernalizationrequirement were used and, for all traits, QTLs were mapped on chromosome 5H. The vernalization response QTL coincides with previous reports at the Vrn-1/Fr1 region of the Triticeae. We also found coincident QTLs at this position for all measures of low-temperature tolerance. Using Composite Interval Mapping, a second proximal set, of coincident QTLs for low-temperaturetolerance, and the accumulation of two different COR proteins (COR14b and TMC-Ap3) was identified. The HvCBF4 locus, or another member of the CBF loci clustered in this region, is the candidate gene underlying this QTL. There is a CRT/DRE recognition site in the promoter of cor14b with which a CBF protein could interact. These results support the hypothesis that highly conserved regulatory factors, such as members of theCBF gene family, may regulate the stress responses of a wide range of plant species.