Application of AFLP, RAPD and ISSR markers to genetic mapping of European and Japanese larch

Genetic linkage maps have been increasingly developed for a wide variety of plants, using segregating populations such as F2S Or backcrosses between i nbred lines. These pedigrees are rarely available in outbred species like f orest trees which have long generation times. Thus genetic mapping studies have to use peculiar pedigrees and markers in appropriate configurations. W e constructed single-tree genetic linkage maps of European larch (Larix dec idua Mill.) and Japanese larch [larix kaempferi (Lamb.) Carr.] using segreg ation data from 112 progeny individuals of an hybrid family. A total of 266 markers (114 AFLP, 149 RAPD and 3 ISSR loci) showing a testcross configura tion, i.e. heterozygous in one parent and null in the other parent, were gr ouped at LOD 4.0, theta=0,3, The maternal parent map (L, decidua) consisted of 117 markers partitioned within 17 linkage groups (1152 cM) and the pate rnal parent map (L. kaempferi) had 125 markers assembled into 21 linkage gr oups (1206 cM), The map distance covered by markers was determined by addin g a 34.7-cM independence distance at the end of each group and unlinked mar ker. It reached 2537 cM and 2997 cM respectively for European larch and Jap anese larch, and represented respectively a 79.6% and 80.8% coverage of the overall genome. A few 3:1 segregating markers were used to identify homolo gous linkage groups between the European larch and the Japanese larch genet ic maps. The PCR-based molecular markers allowed the construction of geneti c maps, thus ensuring a good coverage of the larch genome for further QTL d etection and mapping studies.