The genetic recombination frequencies in barley at 12, 18 and 24°C were compared in two three-point tests with markers on chromosome 6. Two loci, o (orange lemma) and Amyl (α-amylase isoenzyme), 27% recombination apart, were used in both tests. Locus nec2 (necrotic leaf spotting), or a breakpoint in translocation T4-6a, both closely linked with locus o, constituted the third marker point.Significant differences between the estimated recombination frequencies at the three temperatures were not found. If temperature has an effect on the recombination frequency, it is apparently of no importance for mapping gene loci or for barley breeding. However, the recombination frequency may be affected more by temperature when a translocation is involved. A reduced pollen sterility at 12°C was found in the translocation heterozygote; it may be caused by an increased frequency of alternate orientation of the translocation quadrivalent.
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