Molecular characterisation of Onion yellow dwarf virus (OYDV) infecting garlic (Allium sativum L.) in Israel: Thermotherapy inhibits virus elimination by meristem tip culture

Garlic (cv. Shani) was tested using single step RT-PCR and digoxygenin (DIG) labelled dot-blot for a number of viruses. Following sequence analysis it was shown that at least three different polymorphs of the potyvirus Onion yellow dwarf virus (OYDV) infect the same plant simultaneously, together with the potyvirus Leek yellow stripe virus (LYSV), the carlavirus Garlic common latent virus (GCLV) and a multitude of allexiviruses [Shallot virus X (ShVX) related viruses]. Several garlic plants free of all the viruses tested were obtained through meristem-tip culture. Plants infected with single viruses or with different combinations of viruses were similarly obtained. Meristem-tip culture was confirmed as a satisfactory method of virus eradication, while thermotherapy treatment given to mother plantlets before meristem excision was found to specifically antagonise OYDV eradication. This work uses molecular methods for the first time to examine the effectiveness of meristem-tip culture for the eradication of multiple viruses from garlic.