Abstract
In situ hybridization in conjunction with deletion mapping was used to map physically the 18S.26S multigene rRNA family in Triticum aestivum L. cv. Chinese Spring. Using in situ hybridization, we report a new locus in the 7DL arm of Chinese Spring and Aegilops squarrosa, and also confirm the nucleolus organizing region (Nor) locus in the short arm of chromosome 1A at the telomeric end in Chinese Spring. Based on in situ hybridization labeling patterns, we show that rDNA exists as condensed rDNA (heterochromatic) at each end and diffused rDNA within the secondary constriction region of the Nor-B1 (1B), Nor-B2 (6B) and Nor-D3 (5D) loci. In Nor-B1, 80% of the condensed rDNA domain lies in the proximal end and 20% in the distal end joined by diffuse rDNA threads. In Nor-B2, condensed rDNA is distributed evenly at each end joined by diffuse rDNA in the middle. In Nor-D3, the base of the satellite contains a greater concentration of condensed rDNA than the tip of the short arm. On the basis of these observations, we support the model that the usual state of rDNA is inactive (facultatively heterochromatic; Hilliker and Appels 1989). A small fraction of rDNA at a specific location (usually in the middle in wheat) exists as a diffuse region (active) in condensed chromosomes.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Appels R, Dvořák J (1982) The wheat ribosomal DNA spacer region: its structure and variation in populations and among species. Theor Appl Genet 63:337–348
Appels R, Honeycut RL (1986) rDNA: evolution over a billion years. In: Dutta SK (ed) DNA systematics: Plants CRC Press, Boca Raton, pp 82–135
Appels R, Gerlach WL, Dennis ES, Swift H, Peacock WJ (1980) Molecular and chromosomal organization of DNA sequences coding for the ribosomal RNAs in cereals. Chromosoma 78:293–311
Barker RF, Harbred WP, Jarvis MG, Flavell RB (1988) Structure and evolution of the intergenic region of a ribosomal DNA repeat unit of wheat. J Mol Biol 201:1–17
Bedbrook JR, Jones J, O'Dell M, Thompson RD, Flavell RB (1980) A molecular description of telomeric heterochromatin in Secale species. Cell 19:545–560
Bhowal JG (1972) Nucleolar chromosomes in wheat. Z Pflanzenzücht 68:253–257
Brettel RIS, Palotta MA, Gustafson JP, Appels R (1986) Variation at the Nor loci in triticale derived from tissue culture. Theor Appl Genet 71:637–643
Cermeño MC, Orellana J, Santos JL, Lacadena JR (1974) Nucleolar organizer activity in wheat, rye and derivatives analyzed by a silver-staining procedure. Chromosoma 89:370–376
Crosby AR (1957) Nucleolar activity of lagging chromosomes in wheat. Am J Bot 44:813–822
Dvořák J, Zhang HB, Kota RS, Lassner M (1989) Organization and evolution of the 5S ribosomal RNA family in wheat and related species. Genome 32:1003–1016
Endo TR (1986) Complete identification of common wheat chromosomes by means of a C-banding technique. Jpn J Genet 61:89–93
Endo TR (1988) Induction of chromosomal structural changes by a chromosome of Aegilops cylindrica L. in common wheat. J Hered 79:366–370
Friebe B, Kim N-S, Kuspira J, Gill BS (1990) Genetic and cytogenetic analyses of the A genome of Triticum monococcum. VI. Production and identification of primary trisomics using the C-banding technique. Genome 33:542–555
Gerlach WL, Bedbrook JR (1979) Cloning and characterisation of ribosomal RNA genes from wheat and barley. Nucleic Acids Res 7:1869–1885
Gill BS (1987) Chromosome banding methods, standard chromosome band nomenclature, and applications in cytogenetic analysis. In: Heyne EG (ed) Wheat and wheat improvement, 2nd ed. Am Soc Agron, Madison, Wisconsin, pp 243–254
Hilliker AJ, Appels R (1989) The arrangement of chromosomes: Structure and functional aspects. Exp Cell Res 185:297–318
Hutchinson J, Miller TE (1982) The nucleolar organisers of tetraploid and hexaploid wheats revealed by in situ hybridisation. Theor Appl Genet 61:285–288
Jordan EG, Martini G, Bennett MD, Flavell RB (1982) Nucleolar fusion in wheat. J Cell Sci 56:485–495
Lassner M, Dvořák J (1986) Preferential homogenization between adjacent and alternate subrepeats in wheat rDNA. Nucleic Acids Res 14:5499–5512
Lassner M, Anderson O, Dvořák J (1987) Hypervariation associated with a 12-nucleotide direct repeat and inferences on intergenomic homogenization of ribosomal RNA gene spacers based on the DNA sequence of a clone from the wheat Nor-D3 locus. Genome 29:770–781
Liang GH, Wang AS, Phillips RL (1977) Control of ribosomal RNA gene multiplicity in wheat. Can J Genet Cytol 19:425–435
Miller TE, Hutchinson J, Reader SM (1983) The identification of the nucleolus organiser chromosomes of diploid wheat. Theor Appl Genet 65:145–147
Mohan J, Flavell RB (1974) Ribosomal RNA cistron multiplicity and nucleolar organizers in hexaploid wheat. Genetics 76:33–44
Mukai Y, Endo TR, Gill BS (1990) Physical mapping of the 5S rRNA multigene family in common wheat. J Hered 81:290–295
Phillips RL, McMullen MD, Rubenstein I (1988) Ribosomal DNA in maize. In: Gustafson JP, Appels R (eds) Chromosome structure and function. Plenum Publishing, New York, pp 201–214
Rayburn AL, Gill BS (1985) Use of biotin-labeled probes to map specific DNA sequences on wheat chromosomes. J Hered 76:78–81
Author information
Authors and Affiliations
Additional information
by R. Appels
Rights and permissions
About this article
Cite this article
Mukai, Y., Endo, T.R. & Gill, B.S. Physical mapping of the 18S.26S rRNA multigene family in common wheat: Identification of a new locus. Chromosoma 100, 71–78 (1991). https://doi.org/10.1007/BF00418239
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00418239