Physical distribution of recombination in B-genome chromosomes of tetraploid wheat

Several studies have indicated a non-correspondence between genetic and physical distances in wheat chromosomes. To study the physical distribution of recombination, polymorphism for C-banding patterns was used to monitor recombination in 67 segments in 11 B-genome chromosome arms of Triticum turgid...

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Bibliographic Details
Published in:Theoretical and applied genetics 1993-03, Vol.86 (1), p.121-127
Main Authors: Lukaszewski, A.J. (California Univ., Riverside (USA). Dept. of Botany and Plant Sciences), Curtis, C.A
Format: Article
Language:English
Subjects:
Biological and medical sciences
CARTE GENETIQUE
CHROMOSOME
Classical genetics, quantitative genetics, hybrids
CROMOSOMAS
Fundamental and applied biological sciences. Psychology
Genetic mapping
Genetics of eukaryotes. Biological and molecular evolution
GENOMAS
GENOME
Interference
MAPAS GENETICOS
Pteridophyta, spermatophyta
RECOMBINACION
RECOMBINAISON
Recombination
TRITICUM AESTIVUM
Triticum turgidum
Vegetals
Wheat
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Summary:Several studies have indicated a non-correspondence between genetic and physical distances in wheat chromosomes. To study the physical distribution of recombination, polymorphism for C-banding patterns was used to monitor recombination in 67 segments in 11 B-genome chromosome arms of Triticum turgidum. Recombination was absent in proximal regions of all chromosome arms; its frequency increased exponentially with distance from the centromere. A significant difference was observed between the distribution of recombination in physically short and physically long arms. In physically short arms, recombination was almost exclusively concentrated in distal segments and only those regions were represented in their genetic maps. In physically long arms, while a majority of the genetic distance was again based upon recombination in distal chromosome segments, some interstitial recombination was observed. Consequently, these regions also contributed to the genetic maps. Such a pattern of recombination, skewed toward terminal segments of chromosomes, is probably a result of telomeric pairing initiation and strong positive chiasma interference. Interference averaged 0,81 in 35 pairs of adjacent segments and 0,57 across the entire recombining portions of chromosome arms. The total genetic map lengths of the arms corresponded closely to those expected on the basis of their metaphase-1 chiasma frequencies. As a consequence of this uneven distribution of recombination there can be a 153-fold difference (or more) in the number of DNA base pairs per unit (centiMorgan) of genetic length
ISSN:0040-5752
1432-2242
DOI:10.1007/bf00223816