CYTOGENETIC STUDIES ON THE ARTIFICIAL POLYPLOIDS IN THE GENUS ORYZA.
IV. FERTILE ALLOHEXAPLOID RICE, MINUTA-AUSTRALIENSIS
1967 Volume 42 Issue 3 Pages 203-212
Details
1967 Volume 42 Issue 3 Pages 203-212
1. Allohexaploid, minuta-australiensis (2n=72, BBCCEE), was synthesized successfully, treating with 0.05% colchicine the young shoot vegetatively propagated from buds on the node of the F1 hybrid.
2. In MI of PMCs, bivalent chromosomes ranging from 29 to 36, and univalents from 0 to 14 were observed. The average chromosome configuration was 35.12II+1.76I, the mode of bivalents and univalents being 36 and 0 respectively. These bivalents paired tightly. More than a half of univalents observed were assumed to be the result of precocious division of bivalents.
3. In spite of the homogenetic association occurring exclusively in respective three sets of different genomes of the amphiploid, several meiotic irregularities were observed. Accordingly, the fertilities of pollen and seed were unexpectedly low, being 22.8% and 14.4% respectively. Some unknown cause or causes other than the chromosomal homology must have been responsible for such situation.
4. The present amphiploid minuta-australiensis differs from the male-sterile amphiploid sativa-minuta only in its containing E genome instead of A. Therefore, one of the causes of male-sterility of amphiploid sativa-minuta, and perhaps of sativa-latifolia, seems to be found in A genome itself or to be due to the interaction between A and BC or CD genomes. Accordingly, E genome of O. australiensis expressed clearly different effect from A, on the development of anthers in amphiploid level, when brought together with BC genomes.
5. Amphiploid, minuta-australiensis, showed the gigas nature in most characters, and it had fewer tillers and set seeds more sparsely. Under a controlled short-day condition it shot the panicle about 10 days later than the original F1.
