Detection of disease resistance genes by the use of mating designs in poplars and wild cherry
Résumé
Melampsora leaf rust on poplars (Populus sp.) and anthracnosis (Phloesporella padi) on wild cherry (Prunus avium) are serious foliar diseases causing severe growth reduction and even death of susceptible trees. Clonal selection for resistance or tolerance to these diseases is the main goal of the poplar and wild cherry breeding programs at INRA-Orléans. The study of disease resistance or tolerance inheritance is based on appropriate mating designs created in these programs. A 14 x 13 intra- and inter-specific factorial mating design, involving three poplars species (P. trichocarpa, P. deltoides and P. nigra), has been evaluated for rust resistance in nursery trials and in vitro assays. A 14 x 14 half diallel mating design of wild cherry has been evaluated for anthracnosis tolerance in forest trials and in a grafted nursery trial. Qualitative resistance was found in interspecific families and quantitative resistance in intraspecific P. trichocarpa families of poplars: future hybrid clones will take advantage of these two kind of resistance strategies. Only quantitative resistance was observed in wild cherry. Some families of the mating designs, showing a wide distribution for the resistance traits, were chosen to be studied with genetic markers. Genetic maps for each parent and a consensus map will be constructed and used to detect and localize disease resistance genes. The results will bring knowledge about the main genetic components of such complex traits and their possible interactions. The markers close to the resistance genes will possibly be used in a marker-assisted selection scheme.
These investigations are supported by European Community funds (EC-Contracts no AIRI-CT92- 0349 and AIR3-CT93-1585).