Plant & Animal Genome IX Conference

Poster: Large Insert Libraries, Gene Isolation, Etc.
P02_26.html

HAPPY MAPPING IN PLANTS

¹ Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, UK

² MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK

³ USDA-ARS Corn Insects and Crop Genetics Research Unit, Dept. of Plant Pathology, Iowa State University, Ames, Iowa 50011-1020, USA

HAPPY mapping is a physical mapping methodology that possesses the advantages of radiation hybrid mapping but avoids many of the drawbacks, being entirely PCR based. The technique involves the random shearing of intact genomic DNA, segregating the fragments into aliquots each of which contains less than one genome's worth of DNA and measuring the frequency of co-segregation of markers among the aliquots. Each aliquot thus acts as an in vitro analogue of a radiation hybrid cell and together 96 aliquots act as a mapping panel.

An evaluation of HAPPY mapping for high throughput, high resolution physical linkage mapping in plants was undertaken in Arabidopsis thaliana using the sequenced 1.8 Mbp Fca contig. A total of 107 STS markers were selected to cover the region and hemi-nested primer sets designed for each. These primer sets were used on two HAPPY mapping panels constructed from megabase-size DNA prepared from Arabidopsis leaf material. A HAPPY map was constructed from the pairwise data derived from the segregation patterns of the STS markers and compared to the physical distances between the STS markers derived from the published sequence. This comparison showed an excellent conservation of both the relative order and physical distance between markers.

Following its successful application in the model species, HAPPY mapping is now being used in genetic studies in barley, a crop species with a large genome, in order to elucidate the comparative physical architecture of the complex powdery mildew resistance Mla locus.