Characters of the resting, the mitotic prophase and metaphase chromosomes in three species of Thymus were studied. The species studied had commonly resting chromosomes of the complex chromocenter type and mitotic prophase chromosomes of the proximal type. Thymus mongolicus showed the chromosome numbers of 2n=26 and 27 and T. przewalskii and T. roseus showed the chromosome number of 2n=26. The chromosome number of 2n=26 for T. przewalskii and that of 2n=27 for T. mongolicus were reported here for the first time and that of 2n=26 for T. roseus and T. mongilicus verified the previous reports. The chromosome number of 2n=27 for T. mongolicus seemed to have one B-chromosome as 2n=26+1B with respect to the existence of a peculiar heteropycnotic body at resting stage and high pollen stainability. Three species were commonly placed in the diploid level if the basic chromosome numbers of x=13 was accepted. Their karyotypes at mitotic metaphase were quite similar to each other regarding chromosome sizes, chromosome types according to the centromeric position and mono-modality of chromosome lengths from the longest to the shortest chromosomes except for satellite sizes.

View full abstract

The chromosome numbers of four species of Ochrosia sensu lato (Apocynaceae) were reported: those of Neisosperma glomerata (2n=22) and Neisosperma citrodora (2n=23) were documented here for the first time, while those of Neisosperma oppositifolia (2n=22) and Ochrosia coccinea (2n=22) verified the previous counts.

View full abstract

DNA polymorphisms among four accessions of Alocasia odora and five accessions of A. cucullata in Ishigaki Island, Japan were investigated by Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeat (ISSR) markers and sequence data of ITS nrDNA from similar accessions of A. odora, two accessions of A. cucullata and a sequence of A. odora from DNA Data Bank (AF-469030) were analyzed. Clear and reproducible RAPD banding patterns were revealed by 11 of 20 OPA Primers and eight of 20 OPB Primers, whereas ISSR banding patterns were shown by 10 of 100 UBC Primers. The RAPD and ISSR data generated 195 and 54 polymorphic bands, respectively. According to Jaccard's coefficient, genetic similarity among accessions of A. odora and A. cucullata were varied from 4.67 to 44.12 for RAPD and from 6.90 to 80.65 for ISSR. Cluster analysis of RAPD and ISSR data by UPGMA showed two clusters. On RAPD analysis, cluster A consisted of A. odora accession 1 and cluster B consisted of all other A. odora and A. cucullata accessions. Whereas on ISSR analysis, the accessions were separated based on the species. Analysis of 30 sequence data of those species showed that A. odora and A. cucullata could not be separated, even among the sequences within individual. Clearly, ITS nrDNA sequence data could not resolve intragenome and intergenome of Alocasia odora and A. cucullata. This study suggested that the genetic marker method is more appropriate to analyze population structure in A. odora and A. cucullata than ITS nrDNA sequence data analysis.

View full abstract

Artificial cross between Chrysanthemum lavandulifolium (2n=18 diploid) and C. chanetii (2n=36, tetraploid) made succesfully interspecific F₁ hybrid (2n=36 tetraploid instead of 2n=27 tripolid) for the first time. The F₁ hybrid had 12 signals of 45S rDNA and and four signals of 5S rDNA by FISH. The chromosome complement of the F₁ hybrid showed each set of the both parental chromosomes by GISH by using the biotin labeled probe of C. lavandulifolium mixed with approximately 20X blocking DNA of C. chanetii. Eighteen yellow-green colored chromosomes were hybridized with the probe of C. lavandulifolium, that could be involved with C. lavandulifolium, while the other 18 orange-red colored chromosomes were not GISH-hybridized chromosomes with the probe, that could be involved with C. chanetii. The extra nine chromosome set in the hybrids might be resulted due to duplication of the haploid chromosome set of C. lavandulifolium at/after fertilization.

View full abstract

Chromosome numbers and karyotypes of Corylopsis glabrescens and C. gotoana in the Hamamelidaceae were investigated. Corylopsis glabrescens was diploid with 2n=24=14m+8sm+2st, while C. gotoana was tetraploid with 2n=48=36m+8sm+4st. The karyotype of the diploid C. glabrescens was different from that of the diploid C. pauciflora previously reported in Japan, suggesting a heterogeneous origin of the two species. The karyotype of the tetraploid C. gotoana seemed to share a homogeneous karyotype composition with the hexaploid C. spicata previously reported in Japan.

View full abstract