Expression levels of barley Cbf genes at the Frost resistance-H2 locus are dependent upon alleles at Fr-H1 and Fr-H2.

Genetic analyses have identified two loci in wheat and barley that mediate the capacity to overwinter in temperate climates. One locus co-segregates with VRN-1, which affects the vernalization requirement. This locus is known as Frost resistance-1 (Fr-1).