Karyomorphology of four species and one variety of Japanese Mosla were observed. They had commonly chromosomal characters at resting nuclei of the complex chromocenter type, and the mitotic metaphase cells showed 2n=36 for M. japonica, 2n=18 for M. chinenis, M. scabra, M. dianthera and M. dianthera var. nana. The chromosome numbers of 2n=18 and 36 were considered diploid and tetraploid, respectively if the basic number x=9 was accepted. The chromosome number of 2n=18 for M. dianthera var. nana was reported here for the first time, and that of the other four species were verified with the previous reports. The karyotypes of five taxa had commonly similar karyomorphology to each other except for chromosome numbers; small sized chromosomes (2.2 to 1.1 μm long), mono-modal (gradual) decrease in chromosome length from the longest to the shortest chromosomes, and consists of median- and submedian-centromeric chromosomes.

View full abstract

Two molecular cytological phenomena such as NOR and/rDNA loci in the chromosome complement of Scilla scilloides were observed by in situ hybridization using rDNA probe. Most of the plants of the species collected in Shaanxi Province, the People’s Republic of China were diploid of genome A that was characterized by a pair of satellited a₂ chromosomes carrying heavy rDNA signal at the secondary constriction comprising of constricted region and its adjacent chromosome arms at metaphase. At interphase the rDNA signals dispersed in the nucleolus with condensed signal body at terminal end. A plant of AA diploid showed that rDNA signal of one a₂ chromosome condensed through the cycle of respective division, whereas that of another a₂ chromosome showed the normal behavior. Another phenomenon occurred frequently in small B-chromosomes in S. scilloides. The diploid and tetraploid plants of the genome B collected in Jiangsu had several small B-chromosomes carrying condensed rDNA signal in addition to b₁ chromosomes with heavy rDNA signal at metaphase and interphase, suggesting rDNA of small B-chromosomes did not involve to nucleolus organization.

View full abstract

Ptarmica impatiens L.(diploid; 2n=18), P. ledebouri (Heimerl.) Serg.(tetraploid; 2n=36) and P. salicifolia (Bess.) Serg. (tetraploid; 2n=36) taxonomically close relatives with and are sometimes placed in the genus Achillea grown commonly in the well northern colder region. The karyotypic comparison showed Ptarmica is somewhat different from Achillea although they were placed in the tribe Anthemideae, the family Asteraceae. Ptarmica should be independent genus separated from Achillea and more meritorious in an ornamental and horticultural purposes.

View full abstract

Mutation induction in tissue-cultured shoot primordia of Glebionis coronalia was experimented by the exposure of γ-ray for total 15 Gy at the distance of 124 cm for 2 hrs. for a purpose of mutation breeding at the gamma room, the Institute of Radiation Breeding, National Institute of Agrobiological Sciences, Hitachi-Ohmiya, Ibaragi Prefecture, Japan. They were recultured in 1/2 MS liquid medium supplemented with 0.02, mg/l NAA and BAP in combination at 24°C temperature and 9,960 lux light intensity and propagated on the rotary culture equipment (two rotations per minute) and then, were, then, transferred on the gelrite solid medium supplemented with 0.2 mg/l NAA and 2.0 mg/l BAP. At plant regeneration stage at a month old, some plantlets were acclimatized on soil for chrysanthemum cultivation. They set flowers with abnormal head inflorescences after two weeks. Further tests for usefulness are expected.

View full abstract