THE EUROPEAN PRUNUS MAPPING PROJECT - PROGRESS IN THE ALMOND LINKAGE MAP

Six European research groups are collaborating to develop genetic mark ers and linkage maps for use in Prunus breeding programmes. A basic ma p with 200 RFLPs and 50 more markers including isozymes and RAPDs will be constructed using two highly segregating populations: an interspec ific peach x almond F-2 and a cherry F-2. Then, the parents of eleven almond, cherry, peach or plum breeding progenies segregating for targe t characters will be screened for polymorphisms at the marker loci, an d a set of reduced maps, one per progeny, will be constructed with mar kers spaced 20-30 cM and covering the whole genome. Cosegregation anal ysis of markers and characters of interest will allow us to find linka ges between markers and major genes or quantitative trait loci respons ible for the expression of these traits. A map with 72 markers, 7 isoz ymes and 65 RFLPs, has been developed at the IRTA-Cabrils laboratory u sing an intraspecific almond progeny, 'Ferragnes' x 'Tuono'. Probes fo r the analysis of RFLPs were obtained from almond genomic and cDNA lib raries. The level of polymorphism for RFLPs and the distribution of ma rkers in the chromosomes of almond are discussed.