Grapevine rupestris stem pitting virus: a new pathogen of grapevine in Serbia

Grapevine rupestris stem pitting-associated virus (GRSPaV), a member of the genus Foveavirus , is a commonly detected grapevine virus around the world. Despite the broad and global distribution of GRSPaV, no information on its presence in Serbia had been available before this study. In October 2018, 3-year-old grapevine plants of ‘Cabernet Sauvignon’ showing reduced growth and leaf reddening were observed in the vicinity of Krnjevo locality. The results of an mRT-PCR test showed that only samples prepared from cortical scrapings of mature symptomatic grapevine canes yielded an amplicon of 155 bp that confirmed the presence of GRSPaV. No amplification products were recorded in samples prepared from basal leaves or petioles. A serological assay confirmed the presence of GRSPaV in all tested mature cane samples. For further analyses, the CP (coat protein) genes of two selected isolates (VL8 and VL15) of naturally infected grapevine canes were partially sequenced and six sequence variants were determined, showing a certain variability among them. The constructed phylogenetic tree revealed the grouping of Serbian sequence variants into separate subgroups within the same phylogenetic lineage. This is the first report of GRSPaV present in Serbia. Further monitoring and increased phytosanitary control measures are needed to prevent potential spreading and introduction of new virus variants.