CHERRY LEAFROLL VIRUS IN JUGLANS REGIA IN THE LAKE VAN BASIN OF TURKEY

Walnut orchards of the Lake Van basin (Turkey) were surveyed from June to October 2006 to determine the incidence of viral infections. ELISA and RT-PCR were used to investigate the presence of Cherry leaf roll virus (CLRV) and Plum pox virus (PPV), testing a total of 870 samples collected from traditional seed-grown plantations. Whereas no PPV was detected in any of the samples, CLRV was found for the first time in the surveyed locations with an average incidence of 12.9%. Two viral isolates from Edremit were mechanically transmitted to Chenopodium amaranticolor in which they caused local chlorotic spots followed by development of small leaves and apical necrosis. A 366 bp DNA fragment was amplified by RT-PCR from the noncoding region of RNA-2 of both viral isolates and sequenced. Isolate Edremit-2 was 93-98% identical to the comparable sequences of other isolates for which information is available, whereas isolate Edremit-1 had a lower sequence identity (53-46%). The size of the coat protein subunits of both viral isolates was 52.4 kDa as determined by electrophoresis.