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ARS Home » Midwest Area » Columbia, Missouri » Plant Genetics Research » Research » Publications at this Location » Publication #85324
Title: PHYSICAL MAPPING OF GENETICALLY MAPPED MOLECULAR MARKERS IN HOMOEOLOGOUS GROUP 7 CHROMOSOMES OF WHEAT BY IN SITU HYBRIDIZATION

Author
item CHEN, JIANMIN - YANZHOU UNIV, PRC
item Gustafson, J

Submitted to: Journal of Jiangsu Agricultural College
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Genetic maps of wheat are constructed with markers showing genetic "distances" or recombination frequencies which do not correspond to physical distances along the chromosome. By combining microscopic analysis of labeled chromosomes and molecular techniques, it was possible to determine the physical location of DNA markers on individual chromosomes of wheat. The results indicated that the linear order of markers was essentially the same on the chromosomal and genetic maps while distances varied. This research will be useful for mapping genes engineered into wheat.

Technical Abstract: In situ hybridization with biotin-labeled DNA probes was used to determine the physical location of markers from an RFLP-based genetic map of homoeologous group 7 in wheat (Triticum aestivum L.). The observed results indicated all probes hybridized to the corresponding group 7 chromosomes of all three wheat genomes and that the gene order on the physical map was basically the same as that of the RFLP-based genetic map. The distances from the centromere on the physical map was different from those shown on the genetic maps. Comparison of the genetic distance and the physical distance between two pairs of markers (Xpsr129 to Xpsre121, and Xpsr129 to Xpsr117) showed that the region between Xpsr129 and Xpsr121 contains a potential "hot spot" of recombination on the chromosome arm. There appear to be considerable differences in crossing over along the chromosomes. Most of the polymorphic markers are physically located in the middle portion of the chromosome arm to which they were genetically located, indicating reduced recombination in the centromeric and telomeric regions. Markers on the physical map were generally located outside the C-banded regions. The translocation breakout involving 7BS and a co-linear relationship among the homoeologous group 7 chromosomes are discussed.