Susceptibility and Tolerance of New French Prunus domestica Cultivars to European Stone Fruit Yellows Phytoplasmas

Five new cultivars of French prune "Prune d|Ente# and 00 cultivars or new clones of greengage "Reine Claude# were bud!inoculated with European stone fruit yellows "ESFY# phytoplasmas and evaluated for their host response in the nursery over a period of 5 years[ The ESFY infection was con_rmed by speci_c polymerase chain reaction "PCR# detection and 3?\5!diamidino!1! phenylindole "DAPI# staining in all Prunus domestica cultivars tested which were\ thus\ all susceptible to ESFY phytoplasmas[ The new Prune d|Ente cultivars were more sensitive as they generally developed ESFY symptoms and showed a mortality of 08)[ The fruit weight was signi_cantly reduced[ No mortality was observed with Reine Claude genotypes and only two cultivars exhibited weak ESFY symptoms[ A new sensitive method was developed to measure the impact of ESFY phytoplasmas on the shoot growth[ A signi_cant growth reduction was found in all Prune d|Ente cultivars but only in four out of 00 Reine Claude genotypes[ Therefore\ the latter were found to be tolerant of ESFY infection[