Genes for frost resistance in wheat

Abstract

Wheat varieties differ in their responses to low temperatures. Genetic studies on frost resistance in wheat are difficult because the effects are quantitative in nature and thus require precise genetic material and reproducible experimental conditions. The detailed diallel analyses indicated that the inheritance of frost resistance is polygenic and mostly additive. Nevertheless, studies using monosomic, ditelosomic and substitution lines have identified specific chromosomes that carry genes responsible for frost resistance. In particular, the chromosomes 5A and 5D appear to carry major genes. Using molecular markers (RFLP, AFLP) and recombinant substitution lines it was shown that the Vrn-A1 (vernalization) and Fr1 (frost resistance) loci were located closely linked on the distal portion of the long arm of 5A, but recombination between them was found (cM = 2). The RFLP markers Xpsr426 and Xwg644 were tightly linked to the Vrn-A1 locus. Loci Vrn-D1 and Fr2 are located on the long arm of 5D. Fr2 and Vrn-D1 are homoeologous to Fr1 and Vrn-A1. A physical map of the Vrn-A1 and Fr1 genes was constructed on chromosome 5A using deletion lines. This cytogenetically based physical map could be useful in further work on genome mapping and gene cloning.