タバコ属植物の細胞遺伝学的研究 XVI

タバコと他の6種との雑種の減数分裂

抄録

The reduction division in PMC's was studied in 6 interspecific hybrids: N. tabacum× N. otophora, N. tabacum×N. longiflora, N. paniculata×N. tabacum, N. knightiana×N. tabacum, N. gossei×N. tabacum and N. megalosiphon×N. tabacum.
1) F₁of N. tabacum (n=24)×N. otophora(n=12) At MI in PMC's of F₁ of N. tabacum×N. otophora, the number of bivalents and trivalents per cell was 12 in total. It then seems that the genome of N. otophora is the same as one of the genomes of N. tabacum. This finding is generally in agreement with Good-speed's data (1954) on hybrids between N. otophora and two varieties of N. tabacum.
2) F₁ of N. tabacum (n=24)×N. longiflora(n=10) At MI in PMC's of F₁ of N. tabacum×N. longiflora, 0-4 chromosome pairs were found, with the mode at 0-1. The frequency of PMC's with 2 bivalents followed that of PMC's with 1 bivalent. PMC's with 3 bivalents were occasionally found and those with 4 bivalents were very rare. Considering such number of bivalents it is difficult to determine whether the few chromosomll affinities are allosyndetic between the genomes of the parents or autosyndetic. between the 2 genomes of N. tabacum. However, Kostoff (1943) found usually 5 to 7 bivalents and rarely 8 or 9 bivalents in this hybrid combination. The cause of the difference between Kostoff's and my own results is unknown.
3) F₁ of N. paniculata (n=12)×N. tabacum(n=24) At MI in PMC's of this hybrid, 0-4 bivalents were found, with the mode at 1. PMC's without bivalents and with 2 bivalents were very frequently observed, but those with 3 and 4 pairs very rarely.