COMBINED RAPD AND RFLP MOLECULAR LINKAGE MAP OF ASPARAGUS

Two linkage maps of asparagus (Asparagus officinalis L.) were construc ted using a double pseudotestcross mapping strategy with restriction f ragment length polymorphisms (RFLPs), random amplified polymorphic DNA s (RAPDs), and allozymes as markers in a population generated from cro ssing MW25 x A19, two heterozygous parents. AU data were inverted and combined with the natural data to detect linkages in repulsion phase. Two sets of data, one for each parent, were formed according to the in heritance patterns of the markers. The maternal MW25 map has a total o f 163 marker loci placed in 13 linkage groups covering 1281 cM, with a n average and a maximum distance between adjacent loci of 7.9 and 29 c M, respectively The paternal A19 map has 183 marker loci covering 1324 cM in 9 linkage groups, with an average and a maximum distance betwee n two adjacent loci of 7.7 and 29 cM, respectively. Six multiallelic R FLPs segregating in the pattern a/c x b/c and eight heterozygous loci (four RAPDs, and four RFLPs segregating in the pattern a/b x a/b (HZ l oci)) were common to both maps. These 14 loci were used as bridges to align homologous groups between the two maps. In this case, RFLPs were more frequent and informative than RAPDs. Nine linkage groups in the MW25 map were homologous to six groups in the A19 map. In two cases, t wo or more bridge loci were common to a group; thus, the orientation o f homologous linkage groups was also determined. In four other cases, only one locus was common to the two homologous groups and the orienta tion was unknown. Mdh, four RFLPs, and 14 RAPDs were assigned to chrom osome L5, which also has the sex locus M.