Sanitation of Tunisian Garlic Ecotypes: Elimination of Major Viruses through Meristem Tip Culture

Abstract

Viral infections present a major threat to garlic production worldwide. In Tunisia, six garlic viruses have been reported: Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV), Shallot latent virus (SLV), Garlic virus A (GarV-A), Garlic virus B (GarV-B), and Garlic virus C (GarV-C). Among these, OYDV, LYSV, and SLV remain the main viruses infecting garlic and causing a substantial production decline. However, no viral sanitation measures have been carried out so far in Tunisia. Therefore, this study aimed to eradicate the main garlic viruses through meristem culture from 30 Tunisian garlic ecotypes maintained in the National Gene Bank of Tunisia. The viral status of mother plants was assessed based on symptoms and one-step RT-PCR using specific primers for OYDV, LYSV and SLV. All mother plants were infected with at least one virus. In single infections, OYDV was the most prevalent (86.7%), followed by LYSV (43.3%) and SLV (10%). Mixed infection included OYDV + LYSV (36.7%) and OYDV + SLV (6.7%), while no LYSV + SLV co-infections were found. Meristem culture effectiveness in freeing plants from virus infection varied depending on virus and infection type. In single infections, LYSV showed the highest sanitation rate (69.24%), followed by SLV (66.67%) and OYDV (42.31%). For OYDV + LYSV co-infections, 63.64% of in vitro-plants were sanitized, with LYSV eliminated in 85.7% of cases and both viruses in 14.3%. OYDV + SLV infections were fully sanitized of OYDV, but 50% of SLV remained. Overall, a mean of 43.33% of in vitro-plants were completely virus-free. These findings may offer a valid solution to the lack of virus-free garlic in Tunisia, providing a reliable method to reduce yield losses and enhance national garlic production.

Keywords:

Allium sativum, RT-PCR, garlic remediation, Tunisia, virus.