Leaf curl in peach: new resistant genotypes and molecular markers

Among parasites on peaches and nectarines; Taphrina deformans (Berck.) Tul., the cause of peach leaf curl, is one of the most widespread and common. Massive amounts of fungicide are spent on preventing this disease every year, with negative effects in terms of pollution, risk to personnel and production cost. A program of controlled crosses was undertaken some years ago to obtain peach varieties resistant to leaf curl. The progeny "DOFI-84.364" obtained by self-pollinating "DOFI 71.043.018" ("Cesarini x Cesarini") was presumed tolerant to T. deformans. In 1990-93 the tolerance of these seedlings was compared with that of two lines of seedlings that were "presumed susceptible." The trees did not receive fungicidal treatment in the two years prior to the study. Until now all results achieved indicate a high level of resistance in the progeny "DOFI-84.364." The progeny "DOFI-84.364" appeared very homogeneous when analysed by RAPD markers with 20 pre-selected primers. The differential gene expression has been analysed by RAP (RNA fingerprinting Arbitrarily Primer) technique, both in sound leaves and sick leaves showing the hypersensitivity reaction to the infection by T. deformans. The results showed the presence of different transcripts in sound leaves and sick leaves; in detail three transcripts could be involved in parasite-host interaction, hence genes involved in the hypersensitivity reaction could be identified.