In vitro evaluation of apricot (Prunus armeniaca L.) resistance to plum pox potyvirus

An in vitro method for evaluating the resistance of apricot to plum pox pot yvirus (sharka) was established. Three assays were performed: A) Micro-graf ting the apricot to be evaluated onto a GF305 seedling that had been germin ated bl vitro and inoculated with PPV by micro-grafting. B) Micro-grafting the apricot onto a shoot of GF305 previously inoculated in vivo and afterwa rds grown in vitro. C) Inoculation of an apricot shoot with an infected chi p-bud of a diseased GF305 grown in vitro. In vitro evaluation showed a high degree of correspondence with evaluations ill vivo, the first method (A) b eing the most effective for evaluating resistance. In vitro evaluation, the refore, could be a suitable method fur determining the resistance to PPV of seedlings obtained in a breeding programme, either as an alternative, or, preferably, as a complement to traditional in vitro evaluation.