Multiparent Advanced Generation Intercross (MAGIC) mapping populations offer unique opportunities and challenges for marker and QTL mapping in crop species.
Researchers from NIAB and the Department of Plant Sciences, University of Cambridge, have constructed the first eight-parent MAGIC genetic map for wheat, comprising 18 601 SNP markers.
The accuracy of the map has been validated against the wheat genome sequence and found an improvement in accuracy compared to published genetic maps. The map shows a notable increase in precision resulting from the three generations of intercrossing required to create the population. This is most pronounced in the pericentromeric regions of the chromosomes. Sixteen percent of mapped markers exhibited segregation distortion (SD) with many occurring in long (>20 cM) blocks.
Some of the longest and most distorted blocks were collinear with noncentromeric high-marker-density regions of the genome, suggesting they were candidates for introgression fragments introduced into the bread wheat gene pool from other grass species.
The researchers further investigated two of these linkage blocks in detail and found strong evidence that one on chromosome 4AL, showing SD against the founder Robigus, is an interspecific introgression fragment.
The completed map is available from http://www.niab.com/pages/id/326/Resources.