RAPD and SCAR markers linked to the Ma1 root-knot nematode resistance genein Myrobalan plum (Prunus cerasifera Ehr.)

The Myrobalan plum (Prunus cerasifera) is a self-incompatible species in wh ich the clones P.2175, P.1079 and P.2980 are highly resistant to all root-k not nematodes (RKN), Meloidogyne spp. Each clone bears a single major domin ant gene, designated Ma1, Ma2 and Ma3 respectively, that controls a high an d wide-spectrum resistance. Bulked segregant analysis (BSA) and random ampl ified polymorphic DNA (RAPD) analysis were both performed to detect markers linked to the Mal gene using three segregating progenies from P.2175 (Ma1 ma1) crossed by three host parents (ma1 ma1). Four dominant coupling-phase markers were identified from a total of 660 10-base primers tested. The res ulting linkage map spans 14.7 cM and comprises three markers located on the same side of Ma1 and one marker located on the other side. The nearest mar kers (OPAL19(720) and OPA16(1400)) are located at 3.7 and 6.7 cM, respectiv ely, on each side of the gene. Among the three markers that could be succes sfully converted into sequence characterized amplified region (SCAR) marker s, two of them (SCAL19(690) and SCAN12(620)) were scored as dominant marker s whereas the third (SCAO19(770)) failed to produce any polymorphism. SCAL1 9, and to a lesser extent SCAN12, can be used reliably in the marker-assist ed selection of Prunus rootstocks. These markers are adequate to identify t he Ma1 RKN resistance gene in intraspecific segregating progenies and will be suitable for the creation of interspecific rootstocks involving Myrobala n plum. Some of the RAPD and SCAR markers for Mal were also recovered in cl ones P.1079 and P.2980, but not in additional host clones, suggesting that Mal, Ma2 and Ma3 are either allelic or at least closely linked.