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Pivot Concepts:
Gene/Protein
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Target Concepts:
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Query: EC:2.7.7.49 (
reverse transcriptase
)
31,746
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Potato virus Y (PVY) is a serious problem for potato production worldwide. The virus reduces both tuber yield and quality, and recent spread of recombinant strains of PVY in potato production areas is largely credited with the spread of potato tuber necrotic ringspot disease (PTNRD) (1). In Mexico, recombinant strains of PVY were reported in at least two states, Chihuahua (4) and the State of Mexico (3); however, no surveys have been conducted in other potato-producing areas, and the spectrum of PVY isolates circulating in the country has remained uncharacterized. In October 2011, a small-scale survey of seed potato was conducted in the state of Jalisco, Mexico, to identify PVY isolates present in fields. Twelve seed potato fields were inspected visually. These represented various generations of seed potato, from nuclear to G2. Leaf samples were collected from plants displaying mosaic, crinkling, and yellowing symptoms, and were tested for PVY. Fifty samples were collected from cultivars Fabula, Mondial, Fianna, Gigant, Caesar, and Adora. Of the 50 leaf samples collected, seven were PVY-positive using the Immuno-strip Kit (Agdia, Elkhart, IN), and six of these were determined to have a N-serotype according to the typing by the Pocket Diagnostics lateral flow kit (Forsite Diagnostics, Ltd., York, UK). PVY-positive samples came from cultivars Fabula (2 with N serotype), Mondial (4 with N serotype), and Fianna (1 with O serotype). Extracts of the seven PVY-positive leaf samples were applied to Whatman FTA cards (Sigma, St. Louis, MO), dried, and transported to the Plant Virology Laboratory at the University of Idaho for further characterization. All samples immobilized on FTA cards were subjected to RNA extraction and standard
reverse transcriptase
(RT)-PCR typing using a set of PVY-specific primers (2) to determine the strain type. All PVY isolates were recombinant. The six N-serotype samples were found to contain recombinant PVY
NTN
isolates and produced characteristic bands of 181 and 452 bp in RT-PCR, which indicated the presence of two recombination junctions in the
HC-Pro
/P3 and VPg regions typical of European PVY
NTN
isolates. The one O-serotype sample was identified as a recombinant PVY
N-Wi/N:O
isolate, and produced 181 and 689 bp bands in RT-PCR, which indicated the presence of one recombination junction in the
HC-Pro
/P3 region. Sequence analysis of RT-PCR products amplified from five samples with N serotype identified them as PVY
NTN
isolates, and from the one with O serotype identified it as PVY
N-Wi/N:O
isolate. Sequence comparisons confirmed that N serotype samples contained PVY isolates most closely related to typical PVY
NTN
sequences (Accession No. EF026075), while the O serotype sample contained the PVY isolate most closely related to PVY
N-Wi
from Europe (HE608963). The data obtained suggest the presence of two different types of PVY recombinants, PVY
NTN
and PVY
N-Wi
, in seed potato in Jalisco. Additional surveillance for these recombinant isolates may be needed, as well as a survey of their effects on tuber quality in production areas. This is the first report of recombinant isolates of PVY often associated with PTNRD circulating in seed potato in Jalisco, Mexico. References: (1) S. M. Gray et al. Plant Dis. 94:1384, 2010. (2) J. H. Lorenzen et al. Plant Dis. 90:935, 2006. (3) V. R. Ramirez-Rodriguez et al. Virol. J. 6:48, 2009. (4) L. Robles-Hernandez et al. Plant Dis. 94:1262, 2010.
...
PMID:First Report of Recombinant Potato virus Y Strains in Potato in Jalisco, Mexico. 3072 3
Wild larkspur, Delphinium glaucum S. Watson, grows throughout most of Alaska along roadsides and in forests and is planted as an ornamental. Leaves containing distinct vein-clearing and chlorotic mosaic symptoms were first noticed on several D. glaucum plants during 2000 at the Georgeson Botanical Garden in Fairbanks, AK. Although affected plants continued to produce normal flowers, by 2008, the plants developed overall stunting. Initially, virus presence was determined by a general differential centrifugation extraction and concentration protocol followed by examination of the partially purified virus and leaf sap by electron microscopy. Filamentous particles approximately 725 nm long were observed. Virion protein extractions analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a putative coat protein (CP) of ~35 kDa. Potyvirus identity (family Potyviridae) was confirmed with universal potyvirus antiserum in western blots and ELISA assays (Agdia, Inc., Elkhart, IN). Exotic larkspur plants, D. elatum L., growing next to diseased D. glaucum plants, did not exhibit symptoms nor were they positive for potyvirus when tested serologically as described previously. Total RNA was extracted from potyvirus-infected leaves and used in
reverse transcriptase
-PCR assays that specifically targeted potyviruses (2,4) to generate genomic segments for identification and sequence analysis. Fragments representing portions of the helper component protease gene,
HC-Pro
(~700 bp), the cylindrical inclusion gene, CI (~700 bp), and the 3'-end (~1.7 kbp) were purified, cloned, sequenced, and deposited in GenBank (Accession Nos. FJ349329, FJ349328, and FJ349327, respectively). The sequenced 3'-end (1,674 nt) revealed a partial nuclear inclusion protein gene, NIb (1 to 630 nt), a CP gene (631 to 1,443 nt), and a 3'-untranslated region (1,447 to 1,674 nt) attached to a poly (A) tail. Blast searches in GenBank for percent identities of the nucleotide and amino acid comparisons resulted in highest similarities in conserved regions among members in the genus Potyvirus. For example, the highest CI, CP, and HP amino acid identities (0 gaps) were 67% with Potato virus A (Accession No. AF543709), 74% with Araujia mosaic virus (Accession No. EF710625), and 65% with Potato virus A (Accession No. AJ131403), respectively. However, none of the identities were sufficient for inclusion with an existing potyvirus species, whereby the CP amino acid sequence identity must be at least 80% (1). Mechanical transmission of purified virus to Chenopodium amaranticolor, C. quinoa, D. elatum, D. glaucum, and Nicotiana benthamiana seedlings was unsuccessful. We conclude that the isolated virus is a new species in the genus Potyvirus and propose the name Delphinium vein-clearing virus (DeVCV). To our knowledge, this is the first report of a virus isolated from D. glaucum and is representative of the growing number of viruses found in native plants (3). The distribution of DeVCV-infected larkspur is not known in managed or natural ecosystems. Identification of new viruses from native plants is important, in that, the host plant may act as a virus reservoir for transmission to other ornamental and crop plants. References: (1) P. H. Berger et al. Family Potyviridae. Page 819 in: Virus Taxonomy-8th Report of the ICTV. C. M. Fauquet et al., eds. Elsevier Academic Press, San Diego, CA, 2005. (2) J. Chen et al. Arch. Virol. 146:757, 2001. (3) I. Cooper and A. C. Jones. Adv. Virus Res. 67:1, 2006. (4) C. Ha et al. Arch. Virol. 153:25, 2008.
...
PMID:Identification and Molecular Characterization of a Potyvirus Isolated from Native Larkspur (Delphinium glaucum) in Alaska. 3076 48
