Toward a cytogenetically based physical map of the wheat genome

Area of Science:

• Plant genetics and genomics
• Cytogenetics
• Wheat breeding

Background:

• Bread wheat (Triticum aestivum) possesses a polyploid genome amenable to cytogenetic manipulation.
• This characteristic facilitates the development of high-resolution physical maps.
• Previous studies noted deletions in wheat progeny with Triticum cylindricum additions.

Purpose of the Study:

• To construct a high-resolution, cytogenetically based physical map of the wheat genome.
• To analyze chromosomal deletions and their impact on physical mapping.
• To develop a consensus physical map for wheat group 7 chromosomes.

Main Methods:

• Utilized deletion mapping with 41 deletions across chromosomes 7A, 7B, and 7D.
• Employed genetically mapped DNA probes for physical map construction.
• Analyzed recombination frequencies in proximal and distal chromosomal regions.

Main Results:

• Deletion mapping proved more efficient than genetic mapping for proximal loci order.
• Relative gene positions were conserved across homologous group 7 chromosomes.
• Identified molecularly tagged chromosome regions (MTCRs) of 1-10 million base pairs.

Conclusions:

• A cytogenetically based physical map integrates chromosome and DNA maps in wheat.
• MTCRs can streamline cloning of agronomically important genes in wheat.
• Physical mapping strategies are effective despite wheat's large genome size and complexity.