Garlic (Allium spp.) viruses: detection, distribution and remediation attempts in a European garlic collection

Garlic is an important vegetable crop in numerous countries used as food and natural based medicine. Similar to the majority of vegetatively propagated plants, garlic may be affected by several viruses that can cause severe crop losses. The present study aimed to screen 105 garlic accessions (mother plants) from 5 European countries (Germany, Czech Republic, Poland, Italy, and France) for possible presence of Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV), Garlic common latent virus (GCLV) and Shallot latent virus (SLV). The occurrence of three Allexiviruses (GarV-A, GarV-B and GarV-C) in mixed assays was also investigated. Meristem-tip culture assays were performed in order to attempt eradication of the studied viruses. Garlic viruses identification was made by ELISA and RT-PCR. ELISA outcomes showed that all 105 garlic accessions were infected by different virus combinations. The OYDV and LYSV were identified, by ELISA, in all countries at 96% and 88,6% respectively and by RT-PCR at 99% and 96%. Furthermore, GCLV and SLV were detected by ELISA in about 88% and by RT-PCR at 89% and 90%, respectively with the exception of the studied Allexiviruses which were not amplified by RT-PCR with ALLEX1/ALLEX2 primers. Smaller meristem size (0,3-1,5 mm) led to better virus elimination efficiency (29%) compared to 8% obtained for the larger size (2-2,5 mm). The outcomes were opposite (16% vs. 90%) for plants regeneration. Virus elimination efficiency was linked to the virus type, e.g., OYDV and LYSV were eradicated at 90% while GCLV and Allexiviruses were difficult to eliminate (57,4% and 55,6% of eradication). Given the economic relevance of garlic crops worldwide and the frequently reported incidence of viral infections, it is important to make virusfree germplasm available. Therefore, investigating the garlic germplasm sanitary status and constantly improving it is of crucial importance aiming to increase the overall garlic production.