Construction of a genetic linkage map and identification of AFLP markers for resistance to root-knot nematodes in peach rootstocks

A genetic linkage map for peach (Prunus persica (L.) Batsch) rootstocks has been constructed using amplified fragment length polymorphism (AFLP) markers in 55 F2 individuals derived from the cross Lovell x Nemared. From 21 different primer combinations, a total of 169 AFLP markers were scored, of which, 153 were assigned to 15 linkage groups covering 1297 centimorgans (cM) of the peach nuclear genome. The average interval between these markers was 9.1 cM. Two genes (Mi and Mij) involved in resistance to root-knot nematodes (Meloidogyne incognita (Kofoid and White) Chitwood and Meloidogyne javanica (Treub) Chitwood) were mapped to a single linkage group (Group I). These two loci were separated by a 16.5-cM interval. One codominant AFLP marker (EAA/MCAT10) was tightly linked to the Mij locus (3.4 cM), and a dominant AFLP marker (EAT/MCAT2) was found to be closely associated with the Mi locus (6.0 cM). These markers are being studied for utilization in peach rootstock breeding with marker-assisted selection.Key words: peach rootstocks, root-knot nematodes, resistance, AFLP, mapping.