Allopolyploidization was investigated in an artificial F₁ hybrid between Chrysanthemum remotipinnum (2n=18) and Chrysanthemum chanetii (2n=36). Homoeologous and non-homologous chromosomes could pair in the PMC of the hybrid that showed complex pairings and configurations at diakinesis. Physical maps of the 5S and 45S rDNA genes were generated by fluorescence in situ hybridization (FISH) for the F₁ hybrid that had four signals of the 5S rDNA sites in four median-centromeric chromosomes and were different from that of C. remotipinnum, which had four signals in two median-centromeric chromosomes. The hybrid did not show any of the double signals 5S rDNA like C. remotipinnum did. FISH signals of 45S rDNA showed that the hybrid had eight signals of the 45S rDNA sites and seemed to keep the four signals of C. remotipinnum. Genomic in situ hybridization (GISH) distinguished respective parental chromosomes in the F₁ hybrid chromosome complement and showed that approximately 18-yellow-colored chromosomes were hybridized with the probe of C. remotipinnum while the other 18 red-colored chromosomes that were not hybridized could be of C. chanetii. GISH detected translocations at different chromosomal sites and duplication exists in the maternal genome side.

View full abstract

Using FISH biotin-labeled-probe of 5S rDNA showed a peculiar FISH signals on the chromosomes of Leucanthemella linearis and Nipponanthemum nipponicum. At the time of using the probe of 5S rDNA after PCR-amplification using genomic DNA of Chrysanthemum boreale (=Dendranthema boreale), six and two FISH signals of 5S rDNA were co-localized with the 45S rDNA regions of sat-chromosomes in the chromosome complement of both L. linearis and N. nipponicum, respectively. Using the probe of the 5S rDNA after PCR-amplification using genomic DNA of N. nipponicum, those FISH signals were two interstitial signals of 5S rDNA sites on two chromosomes of each chromosome complement as well as six and two FISH signals were co-localized with the 45S rDNA regions of sat-chromosomes of both L. linearis and N. nipponicum, respectively. The chromosomes of N. nipponicum also showed a peculiar FISH signals at terminal regions of most chromosomes. FISH signals of telomere sequence repeats were detected on terminal regions all chromosomes of N. nipponicum, while L. linearis showed terminal and interstitial FISH signals indicating existence of chromosomal mutation as translocation and or inversion. The size of the FISH terminal signals of the 5S rDNA sites was not associated or co-localized with the telomeric signals in the chromosomes of N. nipponicum. Use of FISH facilitates the identification of homologous chromosomes and the inference of changes in genome structure among the species. In the present study, the FISH signals that showed the phenomenon of co-localization of the 5S rDNA site with 45S rDNA were detected for the first time. The species genome appears to have undergone structural reorganization and recombination and, thus, formed unique characteristics as a new genome of the species.

View full abstract

Interspecific F₁ hybrid (2n=30-36) was produced for the first time by artificial cross pollination between Chrysanthemum boreale (2n=18, diploid) and C. vestitum (2n=54, hexaploid). The analysis of fluorescence in situ hybridization (FISH) in the 45S and 5S rDNA sites showed that the F₁ hybrid had six and eight signals respectively (instead of eight and six signals of the 45S and 5S rDNA sites respectively) were shown in the F₁ hybrid perhaps due to translocation and recombination. Genomic in situ hybridization (GISH) distinguished respective parental chromosomes in the F₁ hybrid chromosome complement and showed that at the time of using the biotin labeled probe of C. boreale showed approximately 9-yellow-green-colored chromosomes were hybridized with the probe of C. boreale, might related to C. boreale, 18 orange-colored chromosomes might have a commone chromosome homology between C. boreale and C. vestitum, while the other 9 red-colored were not hybridized chromosomes with the probe and could be of C. vestitum.

View full abstract

Molecular phylogeny of 52 species of Pinanga (Palmae) were investigated using the internal transcribed spacer (ITS) sequence data of nuclear ribosomal DNA. Polymorphic sequence data were identified in the ITS region of Pinanga, indicating that concerted evolution is not completely homogenizing ITS repeats in the nuclear genome. The strict consensus of Pinanga used in the study showed that the genus is monophyletic. Pinanga rivularis and P. aristata formed the basal clade; followed by P. albescens, P. brevipes, P. veitchii, P. sessilifolia and P. crassipes as sister taxa; and P. disticha, P. watanaiana, and P. pulchella were sister taxa to the clade containing the sampled species of Pinanga used in the study. In general, two major clades were recognized: first, Pinanga from Wallacea, East Malesia and adjacent region clade and second, Pinanga from West Malesia and adjacent region clade. The clade separation was strongly correspond with geographical distribution and it did not support infrageneric classification based on distichous and sprirally triads flower described by Beccari (1886). Conforming phylogenetic tree generated by ITS sequence data and morphological observations appear that habit, size and form of stem, leaf and inflorescence were not useful characters for infrageneric classification of Pinanga. Examination of phylogenetic relationships using combination of morphological characters including pollen morphology, cytological data, nuclear genome size and DNA sequence data are necessary for providing a more accurate picture of phylogenetic relationships and affords the opportunity to garner insights into evolutionary process of Pinanga.

View full abstract

Byblis filifolia and B. liniflora had the diploidal and the tetraploidal chromosome numbers of 2n=16 and 32, respectively. In condensation behavior from prophase to metaphase, most chromosomes of both species had early condensing segments at the proximal regions. At prometaphase and early-metaphase, all chromosomes except for some small sized chromosomes had decondense segments at the distal regions in both arms. At mid-metaphase, well-spread chromosomes were quite rare to obtain, because all chromosomes at mid-metaphase stage were quite sticky nature, but not earlier stages of metaphase and prophase. The metaphase chromosomes in both species showed a gradual decrease in size from the largest to the smallest. In B. filifolia, total chromosome length at early-metaphase was 40.5 μm, while total chromosome length at mid-metaphase was 23.3 μm. In contrast, B. liniflora showed total chromosome length of 106.1 μm at early-metaphase, and 54.0 μm at mid-metaphase. To compare to the same stage of metaphase, the total length in B. liniflora was nearly twice as long as that of B. filifolia. Two sat-chromosomes were observed in both species.

View full abstract

Chromosome counts in 12 Artemisia species from Russia are presented in this paper. Chromosome numbers of A. czekanowskiana, A. globosa, A. ledebouriana, A. lithophila, A. macilenta, A. pycnorhiza and A. sosnovskyi are reported for the first time. The chromosome counts carried out in A. czekanowskiana (2n=10x=90) and A. macrantha (2n=12x=108) indicate cases of aneusomaty. The presence of a dicentric chromosome and acentric fragments or a B-chromosome is reported for one species. Besides these, genome size in 21 populations of 18 species of Artemisia belonging to the subgenus Dracunculus, mainly from Russia and Mongolia, has been assessed by flow cytometry. The nuclear DNA content ranges from 2C=4.21 to 2C=24.58 pg, and the nuclear DNA content per basic chromosome set (1Cx) from 2.06 to 3.00 pg. The constancy of genome size has been evaluated concluding that there exists a nuclear DNA loss (at the 1Cx-value level) within ascending ploidy levels. Possible correlations between genome size, morphological traits and the phylogenetic position of species have been tested.

View full abstract