Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: 9/14/1998
Publication Date: N/A
Interpretive Summary: A fruit blemishing disease was observed for the first time in Greece on cultivated and wild pear in 1994. About 30% of trees may show disease symptoms which affect the quality and marketable values of fruit as well as the quality of wild pear root stocks. Research in Beltsville has established that apple scar skin viroid (ASSVd) is associated with the disease in both cultivated and wild pears. This is the first report of finding ASSVd incultivated pome fruits in Greece and of its occurrence in a wild host. This information is valuable for understanding viroid epidemiology and for certification and quarantine personnel to prevent the spread of ASSVd in pome fruits in Greece and to other countries through the international movement of germplasm.
Technical Abstract: Apple scar skin viroid (ASSVd) was found in naturally infected wild (Pyrus amygdaliformis) and cultivated pear (Pyrus communis) in Greece using dot-blot hybridization analysis and RT-PCR assays. Scar skin disease, originally observed in a severely damaged commercial pear orchard, was later found widespread in cultivated and wild pear in northern Peloponnesus, Greece. Of 50 fruit, leaf or bark samples from diseased plants, 30% hybridized with ASSVd cRNA probe. The presence of ASSVd in wild pear on the mountains, away from any human interference, suggests that the viroid is native to Greece. Thus, Greece, in the Mediterranean region, is a second center of origin of ASSVd to northeast Asia in China and Japan. ASSVd may have co-existed with wild pear in Greece for centuries or millennia. This species has been the traditional rootstock of pear and apple in Greece, and pear infection has obviously been taking place by grafting on infected rootstock, or using infected budwood. The broad occurrence of the viroid in wild pear trees away from human interference suggests the existence of some natural means of transmission of ASSVd.