Abstract
In order to elucidate the relationship between the A and C genomes, 16 F1 hybrids between the A (O. sativa, O. sativa f. spontanea, O. sativa v. fatua, O. perennis O. breviligulata and O. glaberrima) and CD (O. alta, O. latifolia and O. grandiglumis) genomes were studied cytologically. About 12 completely paired chromosomes were observed at pachytene stage, 0-12 bivalents at diakinesis, and 3-11 at metaphase I. These findings suggest that one of the CD genomes in O. latifolia is partially homologous to the A genome in O. sativa.
On the basis of the pachytene analysis in the F1 hybrid, O. sativa×O. officinalis (Shastry et al. 1960, 1961; Katayama 1964, 1965a) and the results obtained from the F1 hybrids, O. sativa ×O. minuta and O. sativa×O. punctata (Katayama 1965b, unpubl.), the author postulates that bivalents observed in the F1 hybrids, O. sativa×O. latifolia and O. sativa×O. grandiglumis, were derived from partial homology between the A and C genomes.
Judging from these results so far obtained cytologically in the meiosis of the F1 hybrids between the genomes AA and CC, AA and BBCC and AA and CCDD, the author offers the species relationship in the section Sativa as shown diagrammatically in Figure 5.
