Archivio Journal of Plant Pathology

Abstract:

Severe chlorotic mottling, yellow chlorotic spots and patches were observed on a red raspberry plantation near Smolyan (south Bulgaria). Many patches of dead plants suggested that a nematode-transmitted virus could be associated with the disease. Soil samples were taken for nematode search and leaves for virus detection. Xiphinema diversicaudatum (34 nematodes per 100 g of soil) was found in two of the four soil samples analyzed but no common nematode-transmitted viruses were apparently present in the leaf samples analyzed by DAS-ELISA. Therefore, the presence of Raspberry leaf blotch virus (RLBV), which is associated with raspberry leaf blotch disorder in Scotland and England (McGavin et al., 2012) and is also found in Serbia and Finland (Bi et al., 2012), was investigated because of the symptoms observed on the Bulgarian plants. Total RNA was extracted from samples using the RNeasy plant mini kit (Qiagen, USA) and tested for RLBV by RT-PCR using primers 1571/1286 (McGavin et al., 2012). DNA fragments of the expected size (376 bp) from two RLBV isolates were cloned and sequenced. Two sequence variants (GenBank accession Nos HG738848 and HG738849) were obtained with one nucleotide difference in the non-coding region of RNA-5. They shared over 93% nucleotide and 96.1% amino acid identity with RLBV RNA-5 from the UK (FR823303). Both variants were equally present in one of the two samples tested while the second variant (HG738849) was predominant in the other sample. To our knowledge, this is the first report of RLBV in red raspberry in Bulgaria.