Distribution and partial molecular characterization of Grapevine leafroll-associated virus 2 (GLRaV-2) found in Croatian autochthonous grapevine (Vitis vinifera L.) germplasm

Abstract

Study of Grapevine leafroll-associated virus 2 (GLRaV-2) distribution was conducted on 13 Croatian autochthonous grapevine cultivars or cultivars which are supposed to be autochthonous included in clonal selection: Babica, Babi, Glavinusa, Grk, Ljutun, Marastina, Mladinka, Nincusa, Plavina, Plavac mali, Posip, Vlaska and Vugava. All of them are grown in the southern part of Croatian coastal region (Dalmatia). Sampling was done during autumn 2007, and only a few samples of cultivar Babi were also collected during 2008. All samples were tested for the presence of GLRaV-2 using DAS-ELISA test. Out of 1100 tested grapevine accessions, the presence of GLRaV-2 was determined in 45 samples (4.1%). No virus was detected in seven grapevine varieties (Grk, Ljutun, Mladenka, Nincusa, Plavina, Posip, Vlaska). Minimal infection rate was determined in the cultivar Vugava (0.8%) while the most infected cultivar was Babic in which out of 98 analyzed grapevine accessions 33 (33.7%) were positive. All virus-positive tested vines contained mixed infections of several viruses and no vine was infected by GLRaV-2 only. In 14 different, randomly selected grapevine accessions the presence of GLRaV-2 was also confirmed by RT-PCR using the GLR2CP1/GLR2CP2 primer pair. RT-PCR products from four different grapevine accessions were sequenced. Sequences of gene segment coding for the viral coat protein revealed between 97.9% and 99.6% similarity on the nucleotide level, with absolute similarity on amino-acid level. Sixteen grapevine accessions were selected for transmission to herbaceous host Nicotiana benthamiana, but GLRaV-2 was not successfully transmitted to this host. To our knowledge this is the first report of GLRaV-2 in Croatia.