Genetic control of recombination in barley: Variation in recombination frequency measured with inversion heterozygotes

Abstract

Two experiments have been performed to investigate the occurrence of recombination variation in Northwest European barley. In the first experiment ten lines were crossed to an inversion line and the degree of sterility in F2 plants was determined. Significant variation in sterility was found among the inversion heterozygotes, depending on their genetic background. The sterility distributions showed that the major part of the sterility was due to recombination within the inversion loop. In the second experiment, F3 plants from three of the ten combinations were investigated, both with respect to sterility and with cytological methods. Again, clear differences in the amount of sterility were found between the combinations. No effect was obtained, however, when heterozygous F2 plants in the Alva combination were selected for high and low degree of sterility. In the cytological study, the relative distributions of the different configurations in anaphase were used to calculate the crossover frequencies in the invented segment and in the proximal chromosome segment. The frequencies vary in agreement with the other results for the recombination behaviour of the lines. The combined results indicate strongly that genetic variation for recombination exists in barley. The relative difference in crossover frequencies between the lines with the highest and lowest sterility was estimated to be 30 %.