CHROMOSOMAL POLYMORPHISM IN THE HEXAPLOID SPECIES TRILLIUM SMALLII MAXIMOWICZ
1980 年 55 巻 2 号 p. 109-120
詳細
1980 年 55 巻 2 号 p. 109-120
The tetraploid Trillium apetalon Makino (2n=20, SSUU) and the hexaploid T. smallii Maximowicz (2n=30, K2K2SSUU) were found growing associated at two localities, Muroran (Mr) and Hakodate (Hk) in Hokkaido, Japan. Using patterns of H-segments in cold treated chromosomes, analysis of chromosomal variations in both the species and of cytogenetic relationships between both the species was carried out.
In the patterns of H-segments, two of the three pairs of homologous chromosomes in each of chromosomes A to E of T. smallii were identical to those in co-existing T. apetalon which was composed of homoeologous pairs (combinations of two homologous pairs) of the indivisible genome complex SU. The remaining one pair of homologous chromosomes was that of the chromosomally polymorphic genome K1 in T. kamtschaticum Pallas (2n=10, K1K1) rather than the genome K2 in T. tschonoskii Maximowicz (2n=20, K2K2TT). Most of the chromosome types due to the patterns of H-segments of the genome complex SU found in T. smallii were also contained in T. apetalon. In addition, variation of chromosomes in the complex SU was smaller in the former species than in the latter species. Therefore, most of the chromosome types in the complex SU in T. smallii are those derived from T. apetalon. Both species from Muroran were very similar with respect to chromosome types and frequencies of the types in the complex SU. Both species from Hakodate shared the same types of chromosome A, A5 and A6, which were restricted to Hakodate and had attained fixation. It is highly probable that T. smallii in these localities has been present there since its origin by hybridization between progenitor forms of present T. kamtschaticum and T. apetalon.
