Ginseng has long been considered a valuable plant owing to its medicinal properties; however, genomic information based on chromosome characterization and physical mapping of cytogenetic markers has been very limited. Dual-color FISH karyotype and DAPI banding analyses of Panax ginseng C. A. Meyer, 1843 were conducted using 5S and 45S rDNA probes. The somatic chromosome complement was 2n=48 with lengths from 3.3 μm to 6.3 μm. The karyotype was composed of 12 metacentric, 9 submetacentric, and 3 subtelocentric pairs. The 5S rDNA probe localized to the intercalary region of the short arm of pair 11, while the 45S rDNA was located at the secondary constriction of the subtelocentric satellited chromosome 14. DAPI bands were clearly observed for most chromosomes, with various signal intensities and chromosomal distributions that consequently improved chromosome identification. As a result, all 24 chromosomes could be distinguished and numbers were assigned to each chromosome for the first time. The results presented here will be useful for the on-going ginseng genome sequencing and further molecular-cytogenetic studies and breeding programs of ginseng.

/pdf/karyotype-analysis-of-panax-ginseng-c-a-meyer-1843-4utpfi712u.pdf

Karyotype analysis of Panax ginseng C.A.Meyer, 1843 (Araliaceae) based on rDNA loci and DAPI band distribution

Turnip is a biennial crop and, consequently, the creation of pure lines for breeding is a time-consuming process. The production of pure turnip lines using doubled haploids produced in isolated microspore culture has not been sufficiently developed. The aim of the present work was to determine some key factors inducing embryogenesis in the isolated microspore culture of turnip, as well as investigating the manners of embryo development. It was shown that the acidity of the medium is an important factor in embryo production; different optimal pH levels ranging from 6.2 to 6.6 corresponded to individual genotypes. Such factors as the cold treatment of buds and the addition of activated charcoal to the nutrient medium increased the responsiveness of all genotypes studied. The turnip variety 'Ronde witte roodkop herfst' demonstrated a genetic disorder in the development of microspores; namely, non-separation of some microspores from tetrads. In the in vitro culture, each of the daughter microspores developed on its own. This indicates the dependence of the possibility of embryogenesis in the turnip microspore culture on the genotype. Results suggest that the initiation of secondary embryogenesis in primary embryos leads to an increase in the proportion of doubled haploid plants.

Effects of Genotype and Culture Conditions on Microspore Embryogenesis and Plant Regeneration in Brassica Rapa ssp. Rapa L.

A refined Panax ginseng karyotype based on an ultra-high copy 167-bp tandem repeat and ribosomal DNAs.

6 BioBreeding Institute, Ansung 456-756, Korea Abstract: xBrassicoraphanus line BB#5, a new synthetic intergeneric hybrid between Brassica rapa L. ssp. pekinensis and Raphanus sativus L. var. rafiphera induced by N-methyl-N-nitroso-urethane mutagenesis in microspore culture, shows high seed fertility and morphological uniformity. Dual-color fluorescence in situ hybridization (FISH) using 5S and 45S rDNA probes and genomic in situ hybridization (GISH) using B. rapa genomic DNA probe were carried out to analyze the chromosome composition and the meiosis pairing pattern compared to its parental lines. The somatic chromosome complement is 2n = 38, which consists of 17 metacentric and two submetacentric chromosomes with lengths of 2.18 to 5.01 µm. FISH karyotype analysis showed five and eight pairs of 5S and 45S rDNA loci. GISH meiosis pairing analysis showed that 19 complete bivalents were most frequent and accounted for 42% of the 100 pollen mother cells examined. Based on chromosome number, size, morphology, rDNA distribution, and meiosis pairing pattern, both parental genomes of B. rapa and R. sativus appear to exist in xBrassicoraphanus line BB#5, demonstrating its genome integrity. Such stable chromosome constitutions and meiotic pairing patterns in somatic and meiotic cells are very rare in natural and synthetic intergeneric hybrids. Chromosomal studies and genetic and phenotypic changes in allopolyploids are discussed.he results presented herein will be usef ul r fu rther genomic study of x Brassicoraphanus lines and their improvement as promising new breeding varieties.

/pdf/fish-karyotype-and-gish-meiotic-pairing-analyses-of-a-stable-2zloc3zzsd.pdf

FISH Karyotype and GISH Meiotic Pairing Analyses of a Stable Intergeneric Hybrid xBrassicoraphanus Line BB#5

The family Araliaceae contains many medicinal species including ginseng of which the whole genome sequencing analyses have been going on these days. To characterize the chromosomal distribution of 5S and 45S rDNAs and telomeric repeat in four ginseng related species of Aralia elata (Miq.) Seem., Dendropanax morbiferus H. Lev., Eleutherococcus sessiliflorus (Rupr. Et Maxim.) Seem., Kalopanax septemlobus (Thunb. ex A.Murr.) Koidz. Pre-labelled oligoprobe (PLOP)-fluorescence in situ hybridization (FISH) was carried out. The chromosome number of A. elata was 2n = 24, whereas that of the other three species of D. morbiferus, E. sessiliflorus, and K. septemlobus was 2n = 48, corresponding to diploid and tetraploid, respectively, based on the basic chromosome number x = 12 in Araliaceae. In all four species, one pair of 5S signals were detected in the proximal regions of the short arms of chromosome 3, whereas in K. septemlobus, the 5S rDNA signals localized in the subtelomeric region of short arm of chromosome 3, while all the 45S rDNA signals localized at the paracentromeric region of the short arm of chromosome 1. And the telomeric repeat signals were detected at the telomeric region of both short and long arms of most chromosomes. The PLOP-FISH was very effective compared with conventional FISH method. These results provide useful comparative cytogenetic information to better understand the genome structure of each species and will be useful to trace the history of ginseng genomic constitution.

Pre-labelled oligo probe-FISH karyotype analyses of four Araliaceae species using rDNA and telomeric repeat.

The karyotypes of three Brassica species, B. rapa (AA, 2n=20), B. nigra (BB, 2n=16), and B. oleracea (CC, 2n=18), were constructed based on fluorescence in situ hybridization (FISH), using various DNA probes, including 5S rDNA, 45S rDNA, 176 bp centromere satellite repeats, and Cot-100 DNA. The lengths of the somatic metaphase chromosomes ranged from 2.05 to 4.21 ㎛ in B. rapa, 2.37 to 3.13 ㎛ in B. nigra, and 2.94 to 4.44 ㎛ in B. oleracea. The karyotypes were composed of eight pairs of metacentrics and two pairs of submetacentrics in B. rapa, five pairs of metacentrics and three pairs of submetacentrics in B. nigra, and six pairs of metacentrics and three pairs of submetacentrics in B. oleracea. Ten 45S rDNA loci were detected in B. rapa, whereas six were detected in B. nigra, and four were detected in B. oleracea. In addition, six 5S rDNA loci were detected in B. rapa, whereas two 5S rDNA loci were detected in both B. nigra and B. oleracea. Both CentBr1 and CentBr2 originated from the B. rapa centromere sequence were detected in nine and five pairs of chromosomes in B. oleracea, respectively; however, they were not observed in B. nigra. Cot-100Br signals were detected on the centromeric regions of all chromosomes in the three Brassica species; however, BDB signals appeared in the centromere region of B. rapa and B. oleracea, but not in B. nigra.

Karyotype analysis of three Brassica species using five different repetitive DNA markers by fluorescence in situ hybridization.

Total of fifty accessions of Brassica rapa with various morphological characteristics were used for production of double haploid plants though microspore culture in Brassica rapa . Among them, only 30 accessions induced embryos from microspores. The highest efficiency of embryo induction of 1.194 per bud was obtained from IT135449 of turnip type, while 3 accessions of sarson (winter oil) type did not generate embryo. The effect of heat shock periods for embryogenesis was also investigated with 4 accessions (IT135449; Turnip type, IT199710; Chinese cabbage type, IT212886; Pak choi type, IT218043; Summer oil type). The high productions of embryos were observed in IT135449, IT199710 and IT212886 when microspores were pre-cultured to 32˚C for 2 days. In IT218043, high embryogenesis was observed at the 3 days of heat shock treatment. The optimal condition of shoot regeneration for IT199710 was observed in MS medium supplemented with NAA 0.5 mg·L -1 and BAP 1 mg·L -1 . In contrast, the IT135449 and IT212886 were observed high regeneration frequency in MS medium without plant growth regulators. All the plantlets regenerated from microspore-derived embryos have been successfully transplanted to soil, and bud self-pollinated seeds were produced from doubled haploid plants. This indicated that double-haploid genotype was likely generated naturally during embryogenesis process.

/pdf/efficiency-of-microspore-embryogenesis-in-brassica-rapa-nd06v8gazb.pdf

Efficiency of microspore embryogenesis in Brassica rapa using different genotypes and culture conditions

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Karyotype analysis of three Brassica species using five different repetitive DNA markers by fluorescence in situ hybridization.

Efficiency of microspore embryogenesis in Brassica rapa using different genotypes and culture conditions