Plant Genome III Conference Plant Genome III Conference
Linkage group structure in the diploid (2N=2X=14) strawberry (Fragayia sp.) was studied using two mapping populations: 1) the F2 population (n=80) of an intraspecific cross between F. vesca accessions 'Baran Solemacher' (an 'Alpine' variety) and WC6 (a clone collected from the wild in New Hampshire), and 2) the testmass progeny (n=97) of an F. vesca x F. viridis interspecific hybrid. At present, the intraspecific map consists of 81 markers distributed over 7 linkage groups. By using the template mixing method (see companion poster: Davis et al.) to enhance detection of codominant RAPDS, we identified and mapped 9 co-dominant RAPDS, an unusually large number for a RAPD marker map. The map also included 67 dominant RAPDS, an alcohol dehydrogenase AFLP, two isozymes (Pgi-2 and Sdh), and two morphological markers (r = non-runnering; c = yellow fruit). Of the dominant RAPDS, 41 were derived from the WC6 parent and 26 from the 'Wmn Solemacher' parent. The higher molecular weight alleles of 7 out of 9 codominant RAPDs were derived from WC6. Segregation ratios were significantly skewed in four linkage groups, always favoring 'Baron Solemacher' alleles. The interspecific map, which consists of 78 RAPDs and the Pgi-2 and Sdh isozyme loci, has only four linkage groups, one of which is non-linear. This map structure is indicative of multiple translocation heterozygosity in the interspecific hybrid. At least one inversional difference was evident from comparison of marker order between maps.