Detection and indentification of European stone fruit yellows and other phytoplasmas in wild plants in the surroundings of apricot chlorotic leaf roll-affected orchards in southern France

Between 1994 and 1998 a field study was conducted to identify plant hosts o f the European stone fruit yellows (ESFY) phytoplasma in two apricot growin g regions in southern and southwestern France where the incidence of aprico t chlorotic leaf roll was high. A total of 431 samples from 51 different pl ant species were tested for the presence of phytoplasmas by PCR using unive rsal and ESFY-specific primers. ESFY phytoplasma was detected in six differ ent wild growing Prunus species exhibiting typical ESFY symptoms as well as in symptomless dog rose bushes (Rosa canina), ash trees (Fraxinus excelsio r) and a declining hackberry (Celtis australis). The possible role of these plant species in the spread of ESFY phytoplasma is discussed. PCR-RFLP ana lysis of ribosomal DNA amplified with the universal primers was carried out to characterize the other phytoplasmas found. Thus, elm yellows phytoplasm a, alder yellows phytoplasma and rubus stunt phytoplasma were detected in d eclining European field elm trees (Ulmus carpinifolia Gled), in declining E uropean alder trees (Alnus glutinosa) and in proliferating Rubus spp. respe ctively. The presence of rubus stunt phytoplasma in great mallow (Malva syl vestris) and dog rose was demonstrated for the first time. Furthermore, the stolbur phytoplasma was detected in proliferating field bindweed (Convolvu lus arvensis) and a previously undescribed phytoplasma type was detected in red dogwood (Cornus sanguinea). According to the 16S rDNA-RFLP pattern thi s new phytoplasma belongs to the stolbur phytoplasmas group.