Interchromosomal effects of inversions on crossover rate in maize

Summary The influence of heterozygous inversions on heterologous chromosome recombination has been studied in maize.Inv 2a causes an increase in crossing-over rate ofYg-Sh region of chromosome9: the reverse is true for the more proximal regionBz-Wx. The coincidence indexes for the traitYg-Sh-Bz is decreased, while the same index is increased for the regionSh-Bz-Wz. Inv 9a is accompanied by an high recombination rate in the distal region of chromsome2 Lg-Gl, while in the regionGl-V the effect is relatively less pronounced.The results seem to exclude mitotic recombination events, but are less suitable for supporting other specific interpretations. However, taking into considerationDrosophila experiments, our data are not conflicting with the physiological hypothesis proposed byRamel, which, at present, appears to explain most of the experimental results, although some difficulty arises in considering the cases of decreased recombination rate.The possibility of modifying, by genetical means, the recombination potential is of significance in some stage of plant breeding, at least in some species.With 2 Figures in the Text