Leek Yellow Stripe Research Articles

Incidence of main viruses infecting local garlic in Java, Indonesia

Virus infection is one of the challenges in garlic production due to it perpetuates from one generation to the next and its infection caused huge yield reduction. There was still few information regarding virus status on Indonesian local garlic cultivars. This study was aimed to detect four major viruses infecting local garlic in Indonesia, they were members of genus Potyvirus (Onion yellow dwarf virus/OYDV, Leek yellow stripe virus/LYSV), and Carlavirus (Garlic common laten virus/ GCLV and Shallot latent virus/SLV). Garlic samples were obtained from IPB University collection and field survey in Tegal and Karanganyar (Central Java Province). Dot immuno-binding assay (DIBA) was done for initial virus indexing on non-commercial and commercial cultivars. Reverse transcription polymerase chain reaction (RT-PCR) using four specific primers was done to detect virus on commercial cultivars. DIBA from leaf samples showed that virus incidence of OYDV was relatively higher (92.3 to 100%) than GCLV and SLV (84.6 to 100%) from all tested cultivars. On average, ‘Lumbu Hijau’ has the lowest level of virus titter (severity) than other cultivars. The virus incidence of both bulbil and single clover was similar (97 – 100%) while virus titter of OYDV, GCLV, and SLV on bulbil was the lowest than other propagation materials. Detection by RT-PCR from two commercial cultivars showed that ‘Lumbu Hijau’ has less virus incidence than ‘Jawa Lama’. LYSV, OYDV, GCLV were detected on both cultivars but SLV was not found. Further virus indexing using larger number of samples and involving more virus targets needs to be done.

EURALLIVEG: ESTABLISHMENT OF A EUROPEAN CORE COLLECTION BY CRYOPRESERVATION AND VIRUS ELIMINATION IN GARLIC

A European project named EURALLIVEG (Vegetative Allium, Europe’s Core Collection, safe & sound) was performed under Council Regulation EC 870/2004 from 2007 until 2011. It was coordinated by IPK. The main focus of the project was the development of a European integrated Allium Core collection provided by national collections of Germany, Czech Republic, Poland, Italy, France, and Nordic countries. This collection was designed as a part of the European Genebank Integrated System (AEGIS) of the European Cooperative Program for Plant Genetic Resources (ECPGR). The project consists of five work packages: documentation, molecular screening, cryopreservation, virus elimination, and coordination. Main aim was identification of a core collection of the 200 most important garlic accessions. This collection was cryopreserved using vitrification, which is the most economic way for long term storage. A Cryobanks Network was organized by three project partners. This system ensures safe storage of material by adopting a safety duplicate strategy. The documentation of the collection used passport and characterization data, pictures and other information. In addition genetic fingerprinting with AFLP markers was conducted. In the project, the garlic accessions were introduced into meristem culture for virus elimination. Of the viruses present in garlic, Onion Yellow Dwarf (OYDV) and Leek Yellow Stripe (LYSV) Viruses are most harmful. Therefore, because of the impossibility to do all treatments and tests on all germplasm, it was decided to test the major part of the collection on OYDV and LYSV only. However, a specific part with higher priority (backbone subset) was examined for five viruses. Virus detection used ELISA testing.

Further Evidence that Shallot Yellow Stripe Virus (SYSV) Is a Distinct Potyvirus and Reidentification of Welsh Onion Yellow Stripe Virus as a SYSV Strain

ABSTRACT An antiserum to shallot yellow stripe virus (SYSV) was raised and used in combination with a range of other antisera to potyviruses of Allium spp. in electron microscopic decoration experiments. The serological results corroborated an earlier finding that the type isolates of SYSV and Welsh onion yellow stripe virus (WoYSV) are closely related to each other and only distantly related to onion yellow dwarf (OYDV) and leek yellow stripe (LYSV) viruses, the two other major potyviruses infecting Allium spp. Moreover, the decoration results indicated that Japanese potyviruses named OYDV and Wakegi yellow dwarf virus are isolates of SYSV. Sequence analysis of the 3'-terminal regions of the SYSV and WoYSV ge-nomes revealed coat protein (CP) amino acid and 3'-nontranslated region (3'-NTR) nucleotide sequence identities of 95 and 89%, respectively. The CP amino acid and 3'-NTR nucleotide sequences of these viruses differed from those of OYDV and LYSV by >25 and >67%, respectively. The serological and molecular studies showed that SYSV and WoYSV are different strains of a potyvirus distinct from OYDV and LYSV. For priority reasons, we propose that these strains together with the Wakegi-type isolates of OYDV described in Japan be referred to as SYSV and that SYSV isolates from Allium spp. other than shallot be designated as the Welsh onion strain of SYSV (SYSV-Wo).

Characterization of a New Virus from Garlic(Allium sativum L.), Garlic Mite-borne Mosaic Virus.

Flexuous, filamentous virus particles with a length of 700-800nm were detected in garlic (Allium sativum L.) plants showing mosaic symptoms. The virus was sap-transmissible from garlic plants to seven out of 25 plant species tested, inducing local lesions on Chenopodium murale and Gomphrena globosa and a systemic mosaic on garlic. This virus was transmitted by the eriophyid mite, Aceria tulipae Keifer, but not by aphids. Two polypeptides with M.W. 30kDa and 28.5kDa were detected by SDS-PAGE of the purified virus preparation. The virus exhibited no serological relationships with leek yellow stripe, onion yellow dwarf or garlic latent viruses. No cytoplasmic cylindrical inclusions were observed in infected leaf cells of garlic or C. murale. The 3'-terminal nucleotide sequence of 2518bp was determined. It contained three putative open reading frames (ORFs) for 40kDa, 28kDa (a putative coat protein, CP) and 15kDa polypeptides. The arrangement and amino acid sequences of these ORFs show close similarities with those of shallot virus X and garlic virus (GV)-A, -B, -C and -D. The putative CP of the mite-borne virus has 98% amino acid sequence homology with CP of GV-C, but only 60-67% identity with CPs of four other viruses, indicating the classification of the mite-borne virus and GV-C as the same virus. We propose the name garlic mite-borne mosaic virus (GMbMV) for the virus.

Production of virus-free garlic (Allium sativumL.) and shallot (A. ascalonicumL.) by meristem-tip culture

SummaryAll garlic cultivars used for crop production in the UK are infected with two or more viruses. ISEM decoration tests have indicated that onion yellow dwarf (OYDV), leek yellow stripe and shallot latent viruses (SLV) infect some cultivars in various combinations with other unidentified poty- or carlaviruses. The shallot cv Noordhollandse Strogele was infected by OYDV, SLV and a second potyvirus. Virus-free plants of eight garlic cultivars and the shallot cv Noordhollandse Strogele were produced by meristem-tip culture. The percentage of virus-free garlic plants regenerated was increased from 25–50% to 85% when infected parent plants were subjected to thermotherapy at 38 °C prior to tissue culture.