, Volume 103, Issue 3, pp 179–185 | Cite as

New 18S·26S ribosomal RNA gene loci: chromosomal landmarks for the evolution of polyploid wheats

  • Jiming Jiang
  • Bikram S. Gill
Original Articles


Three new 18S·26S rRNA gene loci were identified in common wheat by sequential N-banding and in situ hybridization (ISH) analysis. Locus Nor-A7 is located at the terminal area of the long arm of 5A in both diploid and polyploid wheats. Locus Nor-B6 is located in N-band 1BL2.5 of the long arm of chromosome 1B in Triticum turgidum and Triticum aestivum. ISH sites, similar to Nor-B6, were also detected on the long arms of chromosomes 1G in Triticum timopheevii and 1S in Aegilops speltoides, but their locations on the chromosomes were different from that of Nor-B6, indicating possible chromosome rearrangements in 1GL and 1BL during evolution. The third new locus, Nor-D8, was only found on the short arm of chromosome 3D in the common wheat Wichita. The loss of rRNA gene locus Nor-A3 and gain of repetitive DNA sequence pSc119 on the terminal part of 5AS suggest a structural modification of 5AS. Comparative studies of the location of the 18S·26S rRNA gene loci in polyploid wheats and putative A and B (G) genome progenitor species support the idea that: (1) Triticum monococcum subsp. urartu is the donor of both the A and At genome of polyploid wheats. (2) Ae. speltoides is closer to the B and G genome of polyploid wheats than Aegilops longissima and is the most probable progenitor of these two genomes.


Common Wheat Polyploid Wheat Progenitor Species Terminal Area Aegilops Speltoides 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Jiming Jiang
    • 1
    • 2
  • Bikram S. Gill
    • 1
    • 2
  1. 1.Wheat Genetics Resource CenterKansas State UniversityManhattanUSA
  2. 2.Department of Plant PathologyKansas State UniversityManhattanUSA

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