The European Prunus mapping project Progress in the almond linkage map

Summary Six European research groups are collaborating to develop genetic markers and linkage maps for use inPrunus breeding programmes. A basic map with 200 RFLPs and 50 more markers including isozymes and RAPDs will be constructed using two highly segregating populations: an interspecific peach × almond F₂ and a cherry F₂. Then, the parents of eleven almond, cherry, peach or plum breeding progenies segregating for target characters will be screened for polymorphisms at the marker loci, and a set of reduced maps, one per progeny, will be constructed with markers spaced 20–30 cM and covering the whole genome. Cosegregation analysis of markers and characters of interest will allow us to find linkages between markers and major genes or quantitative trait loci responsible for the expression of these traits. A map with 72 markers, 7 isozymes and 65 RFLPs, has been developed at the IRTA-Cabrils laboratory using an intraspecific almond progeny, ‘Ferragnes’ × ‘Mono’. Probes for the analysis of RFLPs were obtained from almond genomic and cDNA libraries. The level of polymorphism for RFLPs and the distribution of markers in the chromosomes of almond are discussed.