Cytogenetical Studies in the Inbred Lines of Radish (Raphanus sativus L. var. radicola Pers.) and Their Hybrids
II. Genetic regulation of chiasma frequency
1977 年 42 巻 2 号 p. 273-278
詳細
1977 年 42 巻 2 号 p. 273-278
Mean chiasma frequency at diakinesis has been studied in two inbred lines of radish (Raphanus sativus L. var. radicola Pers), namely LS-337/24 (I12) and LS-337/25 (I12), and their F1, F2 and backcross hybrids. The number of chiasmata per cell was significantly less in the inbred lines (homozygotes) than in their F1, hybrid (heterozygote). F2 hybrid plants, raised from a single plant of F1 hybrid, demonstrated a wide distribution for this character, as would be expected with polygenic control. The value of mean chiasma frequency in F2 hybrid occupied an intermediate position between the lines and the F1 hybrid. Backcross hybrids also showed a marked decline in chiasma frequency when compared to F1, indicating a clear influence of respective inbred lines on this character. It has been concluded that the optimum level of chiasma frequency is a function of heterozygosity of genes and that its distribution is controlled polygenically. The genetic system regulating the formation and distribution of chiasmata in radish has also been discussed.
