1. In the present report, the result of cytological studies on the maturation division of PMC's of TperHRF
1 plants having 2
n=28 chromosomes as the number for the eu-trigeneric triple hybrid was descrived. These F
1 plants were obtained in 1958.
2. At the heterotypic metaphase on meiosis of PMC's of these F
1 plants 0-6 bivalents and 28-16 univalents were observed (Figs. 1-7). The frequency of the bivalents in one PMC was shown in Table 1. Almost all the bivalents consisted of two elements of equal size, but in very rare cases, heteromorphic bivalent was observed (Fig. 8). Most of the bivalents were stick-shaped loosely conjugated end to end, but some of them were ring-shaped joined closely at two ends (1077 ring-shaped in 18224 bivalents). It seems that 4 of the 6 bivalents are raised from autosyndesis of the chromosomes of AB genomes of
T. persicum and the other 2 may be raised from autosyndesis of which V and R genomes of
H. villosa and
S. cereale respectively, considering the results of cytological researches on the intergeneric hybrids between
Triticum,
Secale and
Haynaldia and on the haploid plant of
S. cereale by Kostoff (1937), Nordenskiöld (1939) and Nakajima (1956, '57).
3. Trivalent was observed, though rarely, in addition to bivalents at the heterotypic metaphase, and tetravalent only once among 12600 PMC's.
4. In most individuals of the TperHRF
1 plants used in this research, the meiosis of PMC's showed F
1-type division just as in the
Triticum-Secale F
1 hybrids, but in two individuals (Tper HRF-
1S-5, -S-17) all the 28 univalents were found to form the equatorial plate besides the F
1-type division (Table 2).
5. All the 22 TperHRF
1 plants investigated may be considered as, what might be called, the eu-trigeneric triple hybrid in which AB genomes of
Triticum persicum, V genome of
Haynaldia villosa and R genome of
Secale cereale are completely included.
6. The distribution of chromosomes to opposite poles at the anatelophase in heterotypic division proceeded at random in F-type division, while in the case of the formation of equatorial plate some 28 chromosomes were distributed to each pole (Table 3).
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