First report of leek yellow stripe virus, shallot latent virus, and onion yellow dwarf virus in Garlic from Ecuador

Abstract:

Garlic (Allium sativum L.) is affected by several potyviruses and carlaviruses that induce chlorotic leaf striping, growth reduction, and lead to yield losses. The disease is spread by seed bulbils or cloves due to the vegetative propagation of the crop; this causes accumulation of viruses over generations (Conci et al. 2003; Elnagar et al. 2009). Seventy-one garlic leaves were sampled from symptomatic plants showing mild to severe chlorotic streaking and leaf curling in the fields of an experimental farm in Tumbaco (Pichincha Province). These samples corresponded to clove seeds collected during April 2011 from commercial cultivars; 13 from Pungalá (Chimborazo Province), 8 from Cebadas (Chimborazo Province), 3 from Pelileo (Tungurahua Province), and 47 from local markets in Quito (Pichincha Province). RNA was extracted from 100 mg of leaves or bulbs using a modified Trizol (Invitrogen, Waltham, MA, USA) protocol and analyzed by RT-PCR for Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV), and Shallot latent virus (SLV) using specific primers. Samples came infected from their original fields as proven by positive results from testing bulb tissue. Primers used for LYSV and OYDV detection, modified from Sumi et al. (2001), were: L-F (5′-AAGRGTCAACACTTGGTTTG-3′); L-R (5′-GGTCTCAATCCTAGCTAGTC-3′); O3-F (5′-GAAGCACAYATGCAAATGA AG-3′); and O3-R (5′-YGCCACARCTAGTGGTACAC-3′) respectively. Primers for SLV detection, taken from Majumder et al. (2008), were: S-F (5′-GTGGTNTGGAATTAC-3′) and S-R (5′-CAACATCGATTYTCTC-3′). Based on the individual detection of each virus, a protocol for multiplexed diagnosis was developed using the same specific primers. All samples produced the expected 191-bp fragment covering the 3′ untranslated region (UTR) of LYSV. Sixty-three samples (88.7% of 71) produced the expected 308-bp fragment covering a partial coding sequence of the coat protein gene of SLV. The 8 SLV-free samples corresponded to Cebadas (Chimborazo Province). All samples produced the expected 290-bp fragment covering the partial coding sequence of the coat protein gene along with a region of the 3′ UTR of OYDV. No apparent difference was found in symptoms from plants showing the presence or absence of SLV. One amplicon for each virus, corresponding to Pichincha samples, was sequenced from PCR products. LYSV, OYDV, and SLV isolates (GenBank Accession Nos. KF906255, KF906256, and KF906257, respectively) showed 96%, 94%, and 95% nucleotide sequence identity with previously reported GenBank sequences (Accession Nos. AY007693, JN127344, and AJ409316) from Argentina, Australia, and China, respectively. Our study shows the coinfection of the most important viruses from the genera Potyvirus and Carlavirus in Ecuadorian garlic, necessitating the evaluation and management of effects on production. To our knowledge, this is the first report of LYSV, OYDV, and SLV in garlic from Ecuador.

Año de publicación:

2016

Keywords:

Fuente:

scopus