Theoretical and Applied Genetics

, Volume 109, Issue 7, pp 1346–1352

A high-resolution karyotype of Brassica rapa ssp. pekinensis revealed by pachytene analysis and multicolor fluorescence in situ hybridization

  • Dal-Hoe Koo
  • Prikshit Plaha
  • Yong Pyo Lim
  • Yoonkang Hur
  • Jae-Wook Bang
Original Paper

DOI: 10.1007/s00122-004-1771-0

Cite this article as:
Koo, DH., Plaha, P., Lim, Y.P. et al. Theor Appl Genet (2004) 109: 1346. doi:10.1007/s00122-004-1771-0

Abstract

A molecular cytogenetic map of Chinese cabbage (Brassica rapa ssp. pekinensis, 2n=20) was constructed based on the 4′-6-diamino-2-phenylindole dihydrochloride-stained mitotic metaphase and pachytene chromosomes and multicolor fluorescence in situ hybridization (McFISH), using three repetitive DNA sequences, 5S rDNA, 45S rDNA, and C11-350H. The lengths of mitotic metaphase chromosomes ranged from 1.46 μm to 3.30 μm. Five 45S and three 5S rDNA loci identified were assigned to different chromosomes. The C11-350H loci were located on all the mitotic metaphase chromosomes, except chromosomes 2 and 4. The pachytene karyotype consisted of two metacentric (chromosomes 1 and 6), five submetacentric (chromosomes 3, 4, 5, 9 and 10), two subtelocentric (chromosomes 7 and 8), and one acrocentric (chromosome 2) chromosome(s). The mean lengths of ten pachytene chromosomes ranged from 23.7 μm to 51.3 μm, with a total of 385.3 μm, which is 17.5-fold longer than that of the mitotic metaphase chromosomes. In the proposed pachytene karyotype, all the chromosomes of B. rapa ssp. pekinensis can be identified on the basis of chromosome length, centromere position, heterochromatin pattern, and the location of the three repetitive sequences. Moreover, the precise locations of the earlier reported loci of 5S rDNA, 45S rDNA, and Chinese cabbage tandem DNA repeat C11-350H were established using McFISH analysis. We also identified a 5S rDNA locus on the long arm of pachytene bivalent 7, which could not be detected in the mitotic metaphase chromosomes in the present and earlier studies. The deduced karyotype will be useful for structural and functional genomic studies in B. rapa.

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Dal-Hoe Koo
    • 1
  • Prikshit Plaha
    • 2
  • Yong Pyo Lim
    • 3
  • Yoonkang Hur
    • 1
  • Jae-Wook Bang
    • 1
  1. 1.Department of BiologyChungnam National UniversityDaejeonKorea
  2. 2.Advanced Centre of Hill Bioresources and BiotechnologyHP Agricultural UniversityPalampurIndia
  3. 3.Department of HorticultureChungnam National UniversityDaejeonKorea

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