title: DNA repair and crossing over favor similar chromosome regions as discovered in radiation hybrid of Triticum.
abstract: BACKGROUND
  The uneven distribution of recombination across the length of chromosomes results in inaccurate estimates of genetic to physical distances. In wheat (Triticum aestivum L.) chromosome 3B, it has been estimated that 90% of the cross over events occur in distal sub-telomeric regions representing 40% of the chromosome. Radiation hybrid (RH) mapping which does not rely on recombination is a strategy to map genomes and has been widely employed in animal species and more recently in some plants. RH maps have been proposed to provide i) higher and ii) more uniform resolution than genetic maps, and iii) to be independent of the distribution patterns observed for meiotic recombination. An in vivo RH panel was generated for mapping chromosome 3B of wheat in an attempt to provide a complete scaffold for this ~1 Gb segment of the genome and compare the resolution to previous genetic maps.
  
  
  RESULTS
  A high density RH map with 541 marker loci anchored to chromosome 3B spanning a total distance of 1871.9 cR was generated. Detailed comparisons with a genetic map of similar quality confirmed that i) the overall resolution of the RH map was 10.5 fold higher and ii) six fold more uniform. A significant interaction (r = 0.879 at p = 0.01) was observed between the DNA repair mechanism and the distribution of crossing-over events. This observation could be explained by accepting the possibility that the DNA repair mechanism in somatic cells is affected by the chromatin state in a way similar to the effect that chromatin state has on recombination frequencies in gametic cells.
  
  
  CONCLUSIONS
  The RH data presented here support for the first time in vivo the hypothesis of non-casual interaction between recombination hot-spots and DNA repair. Further, two major hypotheses are presented on how chromatin compactness could affect the DNA repair mechanism. Since the initial RH application 37 years ago, we were able to show for the first time that the iii) third hypothesis of RH mapping might not be entirely correct.
authors: Department of Plant Sciences, North Dakota State University, Fargo, ND 58102, USA.
authors: Ajay
authors: A
authors: Kumar
authors: Filippo M
authors: FM
authors: Bassi
authors: Etienne
authors: E
authors: Paux
authors: Omar
authors: O
authors: Al-Azzam
authors: Monika Michalak
authors: MM
authors: de Jimenez
authors: Anne M
authors: AM
authors: Denton
authors: Yong Q
authors: YQ
authors: Gu
authors: Eric
authors: E
authors: Huttner
authors: Andrzej
authors: A
authors: Kilian
authors: Sachin
authors: S
authors: Kumar
authors: Aakash
authors: A
authors: Goyal
authors: Muhammad J
authors: MJ
authors: Iqbal
authors: Vijay K
authors: VK
authors: Tiwari
authors: Munevver
authors: M
authors: Dogramaci
authors: Harindra S
authors: HS
authors: Balyan
authors: Harcharan S
authors: HS
authors: Dhaliwal
authors: Pushpendra K
authors: PK
authors: Gupta
authors: Gursharn S
authors: GS
authors: Randhawa
authors: Catherine
authors: C
authors: Feuillet
authors: Wojciech P
authors: WP
authors: Pawlowski
authors: Shahryar F
authors: SF
authors: Kianian
mesh_terms: D002843:Chromatin / Q000378:metabolism; D032461:Chromosomes, Plant / Q000235:genetics*; D004260:DNA Repair; D005720:Gamma Rays; D017353:Gene Deletion; D021101:Radiation Hybrid Mapping; D014908:Triticum / Q000235:genetics*
chemical_list: D002843:Chromatin