Cyto-genetical Studies on Tricyrtis III

Polybasic forms in Tricyrtis formosana

抄録

1) The difference in external morphological characters (i.e., in flowers, leaves and stoma cells) was clearly observed among dibasic (2b), tribasic (3b) and tetrabasic (4b) plants in Tricyrtis formosana. Besides these eubasics two hypertetrabasics (4b+1L^t and 4b+1S) and one hypotetrabasic (4b-1S^t) were also described.
2) The dibasic plant (2n=26 (2b)=1L^t₁+1Lⁿ₁+2L+lS^t+1Sⁿ+20S) has two SAT-chromosomes and two nucleolar chromosomes (of terminal type) and respectively corresponding to two large and two small nucleoli in the telophase. The tribasic (2n=39 (3b)=2L^t₁+1Lⁿ₁+3L+2S^t+1Sⁿ+30S) and the tetrabasic (2n=52(4b)=2L^t₁+2Lⁿ₁+4L+2S^t+2Sⁿ+40S) plants have also SAT- and nucleolar chromosomes and respectively corresponding to large and small nucleoli in the telophase. Similar conditions were also found in the three heterobasic plants (cf. table 1).
3) Thirteen bivalents (two long and eleven short pairs) were regularly formed in the first meiotic division of the dibasic plants and very rarely one pair of short chromosomes showed a chromatid bridge. Either a set of thirteen trivalents or that of twelve trivalents, one bivalent and one univalent was frequently observed in the first meiotic division of the tribasic plants (cf. table 2). Various chromosome configurations including many tetravalents and bivalents in the first meiotic divisions of the tetrabasics are shown in table 3. Trivalents with univalents were rarely formed. Univalent chromosomes are distributed at random in the first meiotic division and split longitudinally in the second meiotic division.
The writers express their thanks to the 4th (Genetics) Special Committee of the Japan Society for the Promotion of Scientific Research, by a grant from which this work was partly supported.