CYTOGENETICAL STUDIES ON THE GENUS ORYZA
IV. CYTOLOGICAL STUDIES ON THE FIRST BACKCROSS GENERATION OF THE (A×BC)×A AND (A×CD)×A GENOMES
1967 Volume 42 Issue 3 Pages 169-174
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1967 Volume 42 Issue 3 Pages 169-174
In order to make clear the relationships among the B, C and D genomes, this experiment was designed.
Eight BF1 hybrids, consisting of the F1 hybrids of the A×BC and A genome and the F1 hybrids of the A×CD and A genome, were studied cytologically.
From a large number of flowers pollinated 131 seeds (43 lines) of various degrees of development were obtained. Out of 29 lines (82 seedlings) which grew up to adult plants, 8 were cytologically studied.
At MI, the number of bivalents observed ranged from 8 to 16 (mean=11.97 to 13.20) in the BF1 hybrids of the genomic cross-combinations, ABC×A, from 8 to 15 (mean=11.33 to 12.35) in ACD×A. Based on chromosomal behaviors at meiosis, the author postulated that the number of chromosome pairings between B and C or C and D genomes ranges from 0 to 4 (mean=0.56 to 1.75) or from 0 to 3 (mean=0.17 to 0.43) at the maximum, respectively.
This fact shows that the most of bivalents formed at meiosis of the F1 hybrids in the genomic cross-combinations, A×BC, or A×CD, arose through the homology or partial homology between A and C genomes.
