A MOLECULAR MARKER BASED LINKAGE MAP OF VITIS

Genetic linkage maps of Vitis (2n = 38) have been constructed from a s ingle interspecific hybrid grape population (60 seedlings) of 'Cayuga White' X 'Aurore'. The maps were primarily based on 422 RAPD markers b ut also included 16 RFLP and isozyme markers. These maps had an averag e distance of 6.1 cM between markers and were developed using a double -pseudotestcross strategy. The 'Cayuga White' map had 214 markers cove ring 1196 cM and that of 'Aurore' spanned over 1477 cM with 225 marker s. The 'Cayuga White' map consisted of 20 linkage groups, whereas 22 l inkage groups comprised the 'Aurore' map. The number of groups reduced to 19, as in some instances two or more groups from one parent showed homology with a single group from the other parent on the basis of ma rkers heterozygous in both parents. Each linkage group ranged in size from 14 to 135 cM in 'Aurore' and from 14 to 124 cM in 'Cayuga White'. These maps provide enough coverage of the genome to allow quantitativ e trait locus analysis and map-based gene cloning.