タバコ属植物の細胞遺伝学的研究 V

N. suaveolens と他種の交配3組合せのF₁の減数分裂

抄録

(Reduction divisions in hybrids between N. suaveolens and three other species.) Reciprocal crosses between N. suaveolens (n=16) and four other species, N. gossei (n=18), N. alata (n=9), N. longiflora (n=10) and N. plumbaginifolia (n=10), were carried out. The reciprocal crosses between N. suaveolens and N. gossei gave always many germinating seeds, while the other six crosses did not produce any seeds, with the exception of N. suaveolens×N. longiflora and N. suaveolens×N. plumbaginifolia.
In the meiosis of the PMC's of the hybrid N. suaveolens×N, gossei, the chromosome configurations most frequently found were of the following three types, 2III+14II, 1III+15II+1I and 16II+2I. Besides, several polyvalents were occasionally observed, and many chromosome bridges were seen at first anaphase. This suggests the presence of some inversions or translocations between the chromosomes of N. suaveolens and those of N. gossei.
The study of meiosis in the PMC's of the two hybrids, N. suaveolens×N. longiflora and N. suaveolens×N. plumbaginifolia, agreed very well with Kostoff's observations, the number of bivalents in the former being 0-3 and in the latter 0-4. Since the chromosome configuration 1II+24I was mostly observed in the above two hybrids, it seems that one pair of chromosomes with long homologous parts in common is present among the chromosomes of N, suaveolens and N. longiftora or N, plumbaginifolia.
In the hybrid N, suaveolens×N. longiflora, cells of the tapetum tissue were strikingly enlarged at an early stage of meiosis, and all PMC's, from unknown causes, almost always degenerated and disintegrated before the end of the reduction division.