|Riassunto in Inglese:|
Viroid research on pome and stone fruit trees in Greece is important, as it seems that such viroids are wide spread in the country and may cause serious diseases. Our research dealt with three Pospiviroidae species infecting pome and stone fruit trees, namely Apple scar skin viroid (ASSVd), Pear blister canker viroid (PBCVd) and Hop stunt viroid (HSVd). Tissue-print hybridization, reverse transcription-polymerase chain reaction (RT-PCR), cloning and sequencing techniques were successfully used for the detection and identification of these viroids in a large number of pome and stone fruit tree samples from various areas of Greece (Peloponnesus, Macedonia, Thessaly, Attica and Crete). The 58 complete viroid sequences obtained (30 ASSVd, 16 PBCVd and 12 HSVd) were submitted to the GenBank. Our results showed the presence of ASSVd in apple, pear, wild apple (Malus sylvestris), wild pear (Pyrus amygdaliformis) and sweet cherry; HSVd in apricot, peach, plum, sweet cherry, bullace plum (Prunus insititia), apple, and wild apple; and PBCVd in pear, wild pear, quince, apple and wild apple. This research confirmed previous findings of infection of Hellenic apple, pear and wild pear with ASSVd, pear, wild pear and quince with PBCVd and apricot with HSVd. Our findings also revealed for the first time the natural mixed infection of apple and wild apple with (ASSVd+PBCVd+HSVd), of apple and pear with (ASSVd+PBCVd), and of wild apple with (ASSVd+HSVd), as well as the natural infection of Hellenic sweet cherry, peach, bullace plum and plum with HSVd. To our knowledge, this is the first published report of detecting HSVd and PBCVd in infected apple and wild apple, and ASSVd in sweet cherry.