TS 複二倍体と T. turgidum および S. cereale との戻雑種 F1 の細胞遺伝学的研究
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External characteristics, somatic chromosome numbers and meiosis in PMCs of backcrossed F1 hybrids raised from amphidiploid TS (Triticum turgidum×Secale cereale)×S. cereale (TSRF1) and TS×T. turgidum (TsturF1) were described in details (Table 1).In four out of five plants of back-crossed F1, TS×S. cereale was 2n=28 (Fig. 1). The number 28 corresponds exactly to the sum of the gametic number of the parental plants, i.e., TS (T. turgidum, n=14+S. cereale, n=7)+S. cereale (n=7)=28. A plant, TSRF1 -50-9, was 2n=27 and another one, TsturF1, was 2n=40 (Fig. 23), in the latter 5 chromosomes being in excess of the expected number 2n=35, i.e., TS (n=21)+T. turgidum (n=14)=35. It is suggested that of 40 chromosomes 14 have been derived from T. turgidum and the remaining 26 might have resulted from duplications of 5 chromosomes in the mother plant TS.All five TSRF1 plants obtained were studied cytologically. Number of bivalents at MI in PMCs were 4-8 in F1-48-1, 4-9 in F1-48-7 and F1-50-7, 7-14 in F1-50-6, and 4-10 in F1-50-9 (Figs. 15-22). Four plants gave the mode at 7II; and the remaining one, F1-50-6, at 10II. The average number of bivalents per PMC was 6.14 and 7.25 respectively in the two categories mentioned above (Table 3). The bivalents were consisted of two elements of equal size, and their form was ring- or stick-shaped. In addition to bivalents V-shaped trivalents were observed very rarely; only 3 cases in 1720 PMCs.Of 8-9 bivalents observed in three plants, TSRF1 -48-1, -48-7, and -50-7, four may be due to pairing between the chromosomes of A and B genomes of T. turgidum, and the remaining 4-5 to the pairing between the chromosomes of R genomes brought together one from TS and the other from S. cereale. Taking in account the cytological surveys on hybrids between T. turgidum and S. cereale (Liljefors 1936; Nakajima 1950, 1952a, b), seven of 14 bivalents in TSRF1-50-6 might have resulted from pairing between the chromosomes of R genomes come from TS and S. cereale, and the remaining 7 bivalents from pairing between the chromosomes of A and B genomes from T. turgidum. The genome constitution of TS (2n=42) might be of AABBRR=42 in the light of present observation on the meiosis in PMCs in TS×S. cereale.In TsturF1, PMCs in an anther were very few, the meiosis was highly abnormal, and normal bivalents were very rare (Figs. 24-26). A gigantic PMC (n=ca. 300) caused by the repeated nuclear divisions without cell division, was observed (Fig. 29).
- 日本遺伝学会の論文
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