Utilization of almond as source of plum pox virus resistance in peach breeding

Sharka (Plum pox virus, PPV), mainly affects Prunus species, including apricot, peach and plum. In this work, the resistance to a Dideron isolate of PPV of ten peach (Prunuspersica L.), seven almond [P. dulcis (Miller) D.A. Webb], and eight interspecific peach x almond genotypes were evaluated in controlled conditions in greenhouse. Evaluation was performed by grafting the genotypes onto inoculated GF305 peach rootstocks. For three cycles of study, PPV symptoms were observed in the leaves. To ascertain the presence or absence of PPV, ELISA-DASI and RT-PCR analysis were applied to the leaves. Except for one, peach genotypes showed symptoms and were ELISA-DASI or RT-PCR positive in some of the studied cycles, indicating their susceptibility to PPV. The results demonstrated the high level of resistance to PPV of all almond cultivars assayed, since they did not show any symptoms and were ELISA-DASI and RT-PCR negative. Six out of the seven almond x peach genotypes, also showed a resistant behaviour. The high level of resistance observed in the almond cultivars has been transmitted to the descendants, and the potential role of this species as a source of resistance to PPV in peach breeding programs has been showed.