First report of Bean common mosaic virus, peanut strain, infecting peanut in Argentina

DE BREUIL SOLEDAD; NOME CLAUDIA; FLORES, CEFERINO; BEJERMAN, NICOLÁS; GIOLITTI, FABIÁN; TRUCCO VERONICA; LENARDON, SERGIO

PLANT DISEASE

AMER PHYTOPATHOLOGICAL SOC

Año: 2015

0191-2917

Peanut (Arachis hypogaea L.) is an important oilseed crop inArgentina, where it is used primarily for direct human consumption(confectionery peanut). In the 2009?2010 and 2010?2011 cropping seasons, peanutplants with virus-like symptoms were detected in the growing area of Jujuy andSalta provinces, northwestern Argentina, in fields planted with seeds fromBolivia. Leaf symptoms included systemic mild or severe mottling, blotching andstripes along the lateral veins, sometimes with the presence of chlorotic rings,suggesting the presence of Peanut mottle virus (PeMoV) or peanut strainof Bean common mosaic virus (BCMV-PST). PeMoV and BCMV-PST are membersof the genus Potyvirus (family Potyviridae) and infect peanutcrops in different countries. The symptoms caused by these viruses are oftensimilar in peanut, hindering visual identification (Higgins et al. 1999). A total of 47 symptomatic young leaf samples were collected during bothcropping seasons and tested by dot-blot ELISA using specific polyclonalantisera against PeMoV and BCMV (kindly provided by Dr W. D. Dar, ICRISAT,India). Serological assays revealed that 21 samples were positive for BCMV, 16were PeMoV-positive, and three were coinfected with the two viruses. Thesesamples were also tested by immunocapture (IC) reverse transcription (RT)-PCR (Rowhani et al. 1995), using the Access RT-PCR Kit (Promega, Madison, WI). RT-PCR was performedusing the potyvirus primers PST1, PST2, PeMo14, and PeMo17 (Dietzgen et al. 2001) in all samples. In both serological and molecular methods, positive andnegative controls were included. A single band of the expected size (∼234 bp) wasobtained from serologically BCMV-positive samples, whereas samples infectedwith PeMoV yielded a ∼327-bp fragment. Both fragments were amplified in mixed infections. Theseven samples that were negative in the serological and molecular tests hadsimilar symptoms to those of positive samples, probably due to infections withother viruses, nutritional deficiencies, or other causes. Total nucleic acidsfrom two samples positive for BCMV were purified using CTAB extraction methodand total RNA was sequenced as paired ends (2 × 100 bp) on an IlluminaHiSEquation 1500 platform (INDEAR, Rosario, Argentina). High-quality sequenceswere de novo assembled using the A5 pipeline v-20140401 and the identity ofcontigs was analyzed by BLASTn with an e-value cutoff of 1e-05. BLAST analysessuccessfully identified several contigs corresponding to BCMV-PST genome. Acontig of a nearly complete viral sequence (9,362 nt long), which did notinclude a portion of the CP gene and the 3′ UTR, was deposited into GenBank(KM980459). Multiple sequence alignment of this contig with sequences availablein GenBank showed a high (98 to 99%) nucleotide identity with five BCMVisolates obtained from soybean and peanut from China (KJ807813 and KF439722),Korea (KJ508092), and the United States (U34972 and U05771). These resultsindicate that BCMV-PST is naturally infecting peanut in northwestern Argentina.The virus is transmitted by aphids in a nonpersistent manner and by seeds;therefore, the use of certified virus-free seeds is a preventive strategyagainst pathogen spread to production regions with no history of the virus.