Incidence and genetic diversity of grapevine leafroll-associated virus 3 (GLRaV-3) isolates in Turkey

Grapevine leafroll-associated virus 3 (GLRaV-3) is the most important virus species within the grapevine leafroll complex. It causes significant losses to growers and vineries because of its effect on grape and wine quality. A survey was conducted in the major grape-growing provinces of Turkey in 2018 to investigate distribution and the genetic diversity of GLRaV-3 in local and foreign grapevine cultivars. The genetic diversity of GLRaV-3 isolates based on partial heat-shock protein 70 homologue (Hsp70 h), partial coat protein (CP) and partial RNA-dependent RNA polymerase (RdRp) genes were determined by RT-PCR and sequencing. The infection rate of GLRaV-3 in 141 tested grapevine samples was 13.47% by DAS-ELISA and 28.36% by RT-PCR analysis. Totally, 17 amplicons from Hsp70 h, 22 isolates from RdRp and 16 isolates from CP genes were sequenced in both directions. The sequence analysis of three genes revealed that the Turkish GLRaV-3 isolates shared 91–100% nucleotide identities with the sequences of GLRaV-3 isolated deposited in the GenBank from other parts of the world without any correlation between the distribution and geographical origin. •In this study the incidence and genetic diversity of grapevine leafroll associated virus-3 (GLRaV-3) isolates in Turkey was investigated. The genetic diversity of GLRaV-3 isolates based on partial heat-shock protein 70 homologue (Hsp70 h), partial coat protein (CP) and partial RNA-dependent RNA polimerase (RdRp) genes were determined by RT-PCR and sequences of the isolates were compared with global GLRaV-3 isolates. Totally, PCR products of 17 isolates from Hsp70 h gene, 22 isolates from RdRp gene and 16 isolates from CP gene were sequenced for both directions.•According to the phylogenetic analyses, the sequences of three different genes of Turkish GLRaV-3 isolates clustered with different world isolates with nucleotide sequence identities ranging from 91 to 100% without any correlation between the distribution and geographical origin.•The phylogenetic analysis showed that Turkish GLRaV-3 isolates belong to CP, HsP70h and RdRp gene regions were found in two phylogenetic groups (group I and II) and only one CP isolate (local cv. Sultani) placed in group III.•The results of this study have an important knowledge of genetic diversity of Turkish GLRaV-3 isolates. In order to reduce the incidence and spread of GLRaV-3 in Turkey, the implementation of a certification program is prerequisite to ensure the production and deli