The present study was conducted to establish a protocol for the regeneration of virus-free garlic plants through somatic embryogenesis of two Croatian garlic ecotypes. Basal parts of cloves from mother plants were cultured on a full Murashige and Skoog (MS) or modified MS medium (¼ of KNO₃ and NH₄NO₃ and 2xMgSO₄) containing 0.1 mg L⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) or 1 mg L⁻¹ 2,4-D + 0.5 mg L⁻¹ kinetin (Kin) and representing four different treatments. Plants were regenerated in MS medium containing 0.1 mg L⁻¹ 2,4-D and rooted in a medium containing 0.05 mg L⁻¹ 1-naphthaleneacetic acid (NAA) + 0.005 mg L⁻¹ 6-(γ,γ-dimethylallylamino)purine (2iP). The presence of viruses (i.e., sanitary status) of the mother plants and regenerants was checked by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR). The mother plants were infected with onion yellow dwarf virus (OYDV) and leek yellow stripe virus (LYSV). In addition, the presence of garlic common latent virus (GCLV) was confirmed in four mother plants. Embryogenic callus developed in all four treatments with success ranging from 55% to 81% depending on treatment and ecotype. Plant conversion was significantly higher in somatic embryos developed in media containing 0.1 mg L⁻¹ 2,4-D than those developed in media containing 1 mg L⁻¹ 2,4-D + 0.5 mg L⁻¹ Kin. Virus elimination success ranged from 13.3% up to 62.5% depending on garlic ecotype and treatment. The overall rate of virus elimination by somatic embryogenesis for both treatments and ecotypes were 20.7%, 22.9%, and 30.5% for OYDV, GCLV, and LYSV, respectively. Based on these results, somatic embryogenesis has been shown to be equally or more successful in eliminating garlic viruses compared to other in vitro methods.

The investigation of virus incidence was conducted on 14 autochthonous Croatian grapevine cultivars on vines from 51 vineyard located in the Dalmatian region. A total of 1,116 vines were tested by ELISA on nine viruses: Arabis mosaic virus (ArMV), Grapevine fanleaf virus (GFLV), Grapevine fleck virus (GFkV), Grapevine leafroll-associated virus 1, 2, 3 and 7 (GLRaV-1, GLRaV-2, GLRaV-3 and GLRaV-7), Grapevine virus A and B (GVA and GVB). ELISA confirmed presence of eight viruses: GLRaV-3 in 888 vines (79.6%), GVA 685 (61.4%), GLRaV-1 455 (40.8%), GFkV 223 (19.9%), GFLV 219 (19.6%), GLRaV-2 46 (4.1%), ArMV 36 (3.2%) and GVB 35 (3.1%). Altogether 93 vines (8.3%) were free of all tested viruses, 168 (15.1%) were infected with a single virus, 368 (32.9%) with two, 314 (28.1%) with three, 127 (11.4%) with four, 43 (3.9%) with five, and 3 (0.3%) vines with six viruses. Symptoms of premature leaf color change and downward curling of leaf blades were common, while abnormal branching, short internodes, double nodes and irregular ripening were detected sporadically. The investigation confirms deteriorated sanitary status of all cultivars except Grk and Plavina and indicates the necessity of intensifying grapevine clonal and sanitary selection programs.

The cultivar Plavac Mali (Vitis vinifera L.), the most important indigenous red grapevine cultivar in Croatia, was tested for the presence of 16 grapevine viruses. Thirty-five samples from the collection vineyard were tested for the presence of grapevine leafroll-associated viruses-1, -2, and -3 (GLRaV-1, GLRaV-2 and GLRaV-3, respectively), grapevine fanleaf virus (GFLV), arabis mosaic virus (ArMV), grapevine virus-A (GVA), -B (GVB), -G (GVG), -H (GVH), -I (GVI), -J (GVJ), grapevine fleck virus (GFkV), grapevine rupestris stem pitting associated virus (GRSPaV), and grapevine pinot gris virus (GPGV) by reverse transcription–polymerase chain reaction (RT-PCR). Furthermore, standard PCR was conducted for grapevine badnavirus 1 (GBV-1) and grapevine red blotch virus (GRBV). Mixed infections were most common and GLRaV-3, the most abundant virus found in 85.71% of the vines tested, was further molecularly characterised. Different genomic variants of the heat shock protein homologue (HSP70h) were separated by cloning, detected by single-strand conformation polymorphism (SSCP) analysis, sequenced, and phylogenetically analysed. The presence of phylogenetic groups I and II was only confirmed. This study demonstrates the high virus infection rate of Plavac Mali vines and the heterogeneity of GLRaV-3 present nowadays in a collection vineyard.

Worldwide, virus infections in grapevines are of concern due to the potential for economic loss. Although the grape industry in Mexico is relatively small and focused mainly on the local market, production dates back to the time of the Spanish colonization. This manuscript discusses the findings on grapevine viruses in Mexico. Nine viruses have been identified in the last fifty years, including grapevine red blotch virus (GRBV), grapevine leafroll-associated virus 3 (GLRaV-3), grapevine fanleaf virus (GFLV), and grapevine virus A (GVA). Important information is provided about these viruses and viral pathogens that have not yet been reported in Mexico, but represent an ongoing threat to plant health and grapevine production in other viticultural regions of the world. Strategies for virus control in vineyards are described. The information discussed here should be shared with growers and stakeholders to prevent future negative impacts on the Mexican grapevine industry and to save ancient grapevine accessions.