Garlic (Allium sativum L.) is one of the most important culinary herbs in the Indian subcontinent. Several viruses belonging to genera Potyvirus, Carlavirus, and Allexivirus are known to infect garlic (2,3). Garlic accessions grown on the research farm of the Indian Agricultural Research Institute, New Delhi, were tested for the presence of Onion yellow dwarf virus (OYDV), Shallot latent virus (SLV), and Garlic common latent virus (GarCLV). Leaves showing mild to severe mosaic symptoms were collected in January of 2008 from five accessions of garlic (Pusa Selection-34, G-1, Selection-17, G-282, and PGS-14) from the experimental plots. Direct antigen coated (DAC)-ELISA was performed with antisera to OYDV, GarCLV (Bioreba, Reinach, Switzerland), and Garlic latent virus (GarLV) (synonym for SLV) obtained from D. E. Lesemann, (Braunschweig, Germany). Total RNA was extracted from 100 mg of leaves with the RNeasy Plant Mini kit (Qiagen, Maryland) according to the manufacturer's protocol. Reverse transcription (RT)-PCR and DAC-ELISA confirmed the presence of OYDV and SLV in all selection lines, both of which were reported previously from garlic in India (1). The occurrence of GarCLV was confirmed by DAC-ELISA and RT- PCR using a primer pair 5′-AAATGTTAATCGCTAAACGACC-3′ and 5′-CTTTGTGGATTTTCGGTAAG-3′ designed from the conserved region of open reading frame (ORF) 5 (coat protein) and ORF 6 (nucleic acid binding protein) of GarCLV (GenBank Accession Nos. AB004566, X81138, and X81139). Expected amplicons of ∼500 bp for GarCLV were obtained from all garlic lines tested, confirming that all five garlic lines had mixed infections of OYDV, SLV, and GarCLV. The amplicons obtained from Pusa Selection-34 were directly sequenced and the 536-bp nucleotide sequence (GenBank Accession No. FJ154841) showed a sequence identity of 87% compared with GarCLV (GenBank Accession No. AB004566). To our knowledge, this is the first report of GarCLV in garlic cultivars in India. Our study demonstrates that GarCLV occurs frequently in mixed infections with OYDV and SLV and the potential impact of these mixed infections on garlic production needs to be evaluated.
References: (1) S. Majumder et al. J. Plant Pathol. 90:369, 2008. (2) P. Van Dijk. Acta Hortic. 358:299, 1994. (3) D. G. A. Walkey and D. N. Antill. J. Hortic. Sci, 64:53, 1989.