ANALYSIS OF A DETAILED GENETIC-LINKAGE MAP OF LACTUCA-SATIVA (LETTUCE) CONSTRUCTED FROM RFLP AND RAPD MARKERS

A detailed genetic map has been constructed from the F-2 population of a single intraspecific cross of Lactuca sativa (n = 9). It comprises 319 loci, including 152 restriction fragment length polymorphism (RFLP ), 130 random amplified polymorphic DNA (RAPD),7 isozyme, 19 disease r esistance, and 11 morphological markers. Thirteen major, four minor li nkage groups and several unlinked markers are identified for this geno me which is estimated to be approximately 1950 cM. RFLP and RAPD marke rs show similar distributions throughout the genome and identified sim ilar levels of polymorphism. RAPD loci were much quicker to identify b ut more difficult to order. Procedures for generating accurate genetic maps and their limitations are described.