Plant Molecular Biology

, Volume 48, Issue 5, pp 767–789

A high-density cytogenetic map of the Aegilops tauschii genome incorporating retrotransposons and defense-related genes: insights into cereal chromosome structure and function

  • Elena Boyko
  • Ruslan Kalendar
  • Victor Korzun
  • John Fellers
  • Abraham Korol
  • Alan H. Schulman
  • Bikram S. Gill
Article

DOI: 10.1023/A:1014831511810

Cite this article as:
Boyko, E., Kalendar, R., Korzun, V. et al. Plant Mol Biol (2002) 48: 767. doi:10.1023/A:1014831511810

Abstract

Aegilops tauschii (Coss.) Schmal. (2n=2x=14, DD) (syn. A. squarrosa L.; Triticum tauschii) is well known as the D-genome donor of bread wheat (T. aestivum, 2n=6x=42, AABBDD). Because of conserved synteny, a high-density map of the A. tauschii genome will be useful for breeding and genetics within the tribe Triticeae which besides bread wheat also includes barley and rye. We have placed 249 new loci onto a high-density integrated cytological and genetic map of A. tauschii for a total of 732 loci making it one of the most extensive maps produced to date for the Triticeae species. Of the mapped loci, 160 are defense-related genes. The retrotransposon marker system recently developed for cultivated barley (Hordeum vulgare L.) was successfully applied to A. tauschii with the placement of 80 retrotransposon loci onto the map. A total of 50 microsatellite and ISSR loci were also added. Most of the retrotransposon loci, resistance (R), and defense-response (DR) genes are organized into clusters: retrotransposon clusters in the pericentromeric regions, R and DR gene clusters in distal/telomeric regions. Markers are non-randomly distributed with low density in the pericentromeric regions and marker clusters in the distal regions. A significant correlation between the physical density of markers (number of markers mapped to the chromosome segment/physical length of the same segment in μm) and recombination rate (genetic length of a chromosome segment/physical length of the same segment in μm) was demonstrated. Discrete regions of negative or positive interference (an excess or deficiency of crossovers in adjacent intervals relative to the expected rates on the assumption of no interference) was observed in most of the chromosomes. Surprisingly, pericentromeric regions showed negative interference. Islands with negative, positive and/or no interference were present in interstitial and distal regions. Most of the positive interference was restricted to the long arms. The model of chromosome structure and function in cereals with large genomes that emerges from these studies is discussed.

bread wheatmicrosatellitesmolecular genetic mapnegative and positive interferenceresistance and defense-response genesretrotransposons

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Elena Boyko
    • 1
  • Ruslan Kalendar
    • 2
  • Victor Korzun
    • 3
  • John Fellers
    • 4
  • Abraham Korol
    • 5
  • Alan H. Schulman
    • 2
    • 6
  • Bikram S. Gill
    • 1
  1. 1.Wheat Genetics Resource Center, 4024 Throckmorton Plant Sciences CenterKansas State UniversityManhattanUSA
  2. 2.Institute of BiotechnologyUniversity of Helsinki, Plant Genomics Laboratory, Viikki BiocenterHelsinkiFinland
  3. 3.Institute of Plant Genetics and Crop Plant ResearchGaterslebenGermany
  4. 4.USDA-ARS, Plant Science UnitKansas State UniversityManhattanUSA
  5. 5.Institute of EvolutionUniversity of HaifaMount CarmelIsrael
  6. 6.Crops and Biotechnology, Agrifood Research FinlandJokioinenFinland