MOLECULAR-GENETICS OF RUST RESISTANCE IN POPLARS (MELAMPSORA-LARICI-POPULINA KLEB POPULUS SP) BY BULKED SEGREGANT ANALYSIS IN A 2X2 FACTORIAL MATING DESIGN

With random amplified polymorphic DNA (RAPD) markers, we have tagged a genomic region in Populus sp. involved in qualitative resistance to M elampsora larici-populina. Our approach was based on three steps: use of RAPD markers that can be quickly and efficiently researched; applic ation of ''bulked segregant analysis'' technique on individuals of one interspecific family P. trichocarpa X P. deltoides to search for RAPD markers linked to resistance; and validation of these markers in two other families linked with the first one in a 2 x 2 factorial mating d esign. Of five detected markers, only one marker M03/04_480 was polymo rphic in the three segregating families, involving 89 individuals and four different parents. We have estimated the recombination value of 1 cM with 1 cM sampling error.