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Rännäli M, Czekaj V, Jones RAC, Fletcher JD, Davis RI, Mu L, Dwyer GI, Coutts BA, Valkonen JPT. Molecular Genetic Characterization of Sweet potato virus G (SPVG) Isolates from Areas of the Pacific Ocean and Southern Africa. Plant Dis 2008; 92:1313-1320. [PMID: 30769446 DOI: 10.1094/pdis-92-9-1313] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Sweet potato virus G (SPVG, genus Potyvirus, family Potyviridae) was detected in sweetpotato (Ipomoea batatas) storage roots sold in the local markets and storage roots or cuttings sampled directly from farmers' fields. Using serological and molecular methods, the virus was detected for the first time in Java, New Zealand, Hawaii, Tahiti, Tubuai, Easter Island, Zimbabwe, and South Africa, and also in an imported storage root under post-entry quarantine conditions in Western Australia. In some specimens, SPVG was detected in mixed infection with Sweet potato feathery mottle virus (genus Potyvirus). The coat protein (CP) encoding sequences of SPVG were analyzed for 11 plants from each of the aforementioned locations and compared with the CP sequences of 12 previously characterized isolates from China, Egypt, Ethiopia, Spain, Peru, and the continental United States. The nucleotide sequence identities of all SPVG isolates ranged from 79 to 100%, and amino acid identities ranged from 89 to 100%. Isolates of the same strain of SPVG had nucleotide and amino acid sequence identities from 97 to 100% and 96 to 100%, respectively, and were found in sweetpotatoes from all countries sampled except Peru. Furthermore, a plant from Zimbabwe was co-infected with two clearly different SPVG isolates of this strain. In contrast, three previously characterized isolates from China and Peru were phylogenetically distinct and exhibited <90% nucleotide identity with any other isolate. So far, the highest genetic diversity of SPVG seems to occur among isolates in China. Distribution of SPVG within many sweetpotato growing areas of the world emphasizes the need to determine the economic importance of SPVG.
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Affiliation(s)
- M Rännäli
- Department of Applied Biology, P.O. Box 27, FIN-00014 University of Helsinki, Finland
| | - V Czekaj
- Department of Applied Biology, P.O. Box 27, FIN-00014 University of Helsinki, Finland
| | - R A C Jones
- Agricultural Research Western Australia, Locked Bag No. 4, Bentley Delivery Centre, Perth, WA 6983, and WA State Agricultural Biotechnology Centre, Murdoch University, Perth, WA 6150, Australia
| | - J D Fletcher
- New Zealand Institute for Crop & Food Research, Private Bag 4704, Christchurch, New Zealand
| | - R I Davis
- Northern Australia Quarantine Strategy (NAQS) and Australian Quarantine and Inspection Service (AQIS), P.O. Box 1054, Mareeba, Queensland 4880, Australia
| | - L Mu
- Service du Dévelopement Rural, Département de la Protection des Végétaux, BP 100, Papeete, French Polynesia
| | - G I Dwyer
- Agricultural Research Western Australia, Locked Bag No. 4, Bentley Delivery Centre, Perth, WA 6983, Australia
| | - B A Coutts
- Agricultural Research Western Australia, Locked Bag No. 4, Bentley Delivery Centre, Perth, WA 6983, Australia
| | - J P T Valkonen
- Department of Applied Biology, P.O. Box 27, FIN-00014 University of Helsinki, Finland
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Dwyer GI, Gibbs MJ, Gibbs AJ, Jones RAC. Wheat streak mosaic virus in Australia: Relationship to Isolates from the Pacific Northwest of the USA and Its Dispersion Via Seed Transmission. Plant Dis 2007; 91:164-170. [PMID: 30780999 DOI: 10.1094/pdis-91-2-0164] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Wheat streak mosaic virus (WSMV) was found for the first time in Australia in 2002. It subsequently was found widely dispersed around the continent and was shown to be seedborne in wheat. The coat protein (CP) gene sequences of nine WSMV isolates from eastern and southwestern Australia are reported, one obtained directly from infected wheat seed, three from seedlings grown from infected wheat seed, and five from infected wheat plant samples. These sequences were compared with those of 66 WSMV CP sequences, including eight previously sequenced Australian isolates. All 17 Australian sequences formed a closely knit monophyletic cluster as part of the D1 subclade of WSMV previously only reported from the Pacific Northwest of the United States. The close phylogenetic relationships of these sequences indicate that the Australian outbreak arose from a single incursion, the source of which appears to be the Pacific Northwest. Three Australian CP sequences were identical, one from the location of the post-entry quarantine facility at Tamworth, New South Wales, and two from seed that had originally been propagated at that facility. These three sequences were closest to the Pacific Northwest sequences and differed from them by as little as eight nucleotides (0.76%). The sequence of a third seedborne isolate originally from the same source differed from the other two seedborne isolates by two nucleotides, indicating that the immigrant WSMV population may have been variable. The other Australian sequences differed from the three identical ones by only one to four nucleotides. The phylogenetic pattern and small number of nucleotide differences between individual isolates from different geographic locations fit the scenario that the virus was introduced once in seed of wheat breeding material, multiplied where it was introduced, and then was dispersed over long distances around the Australian continent along standard distribution routes for wheat breeding lines, germ plasm, and crop seed. These conclusions provide a cautionary tale indicating the importance of effective monitoring of imported plant materials for exotic virus diseases during post-entry quarantine.
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Affiliation(s)
- Geoffrey I Dwyer
- Agricultural Research Western Australia, Locked Bag No. 4, Bentley Delivery Centre, Perth, WA 6983, Australia
| | - Mark J Gibbs
- School of Botany and Zoology, Australian National University, Canberra, ACT 2000, Australia
| | | | - Roger A C Jones
- Agricultural Research Western Australia, Locked Bag No. 4, Bentley Delivery Centre, Perth, WA 6983, Australia, and State Agricultural Biotechnology Centre, Murdoch University, Perth, WA 6150, Australia
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Abstract
Under conditions that excluded any possibility of eriophyid mite vector activity, seed transmission of Wheat streak mosaic virus (WSMV) was shown in eight different wheat genotypes at rates of 0.5 to 1.5%. Virus identification in seedlings came from characteristic symptoms in wheat, enzyme-linked immunosorbent assay with WSMV-specific antibodies, reverse-transcription polymerase chain reaction tests with WSMV-specific primers, and cDNA sequence comparisons with published sequences. Sequence comparisons of four seedborne isolates showed ≥98.6% identity with the eight Australian isolates in GenBank, indicating a common seedborne origin of WSMV. These findings warrant reconsideration of currently accepted views on WSMV epidemiology and the likelihood of introducing it to new locations through planting untested wheat seed and the movement of germplasm.
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Affiliation(s)
- Roger A C Jones
- Plant Pathology Section, Department of Agriculture, Locked Bag No. 4, Bentley Delivery Centre, WA 6983, Australia
| | - Brenda A Coutts
- Plant Pathology Section, Department of Agriculture, Locked Bag No. 4, Bentley Delivery Centre, WA 6983, Australia
| | - Alison E Mackie
- Plant Pathology Section, Department of Agriculture, Locked Bag No. 4, Bentley Delivery Centre, WA 6983, Australia
| | - Geoffrey I Dwyer
- Saturn Biotech Ltd., State Agricultural Biotechnology Centre, Murdoch University, WA 6150, Australia
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Dwyer GI, Njeru R, Williamson S, Fosu-Nyarko J, Hopkins R, Jones RAC, Waterhouse PM, Jones MGK. The complete nucleotide sequence of Subterranean clover mottle virus. Arch Virol 2003; 148:2237-47. [PMID: 14579180 DOI: 10.1007/s00705-003-0144-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The complete nucleotide sequence of Subterranean clover mottle virus (SCMoV) genomic RNA has been determined. The SCMoV genome is 4,258 nucleotides in length. It shares most nucleotide and amino acid sequence identity with the genome of Lucerne transient streak virus (LTSV). SCMoV RNA encodes four overlapping open reading frames and has a genome organisation similar to that of Cocksfoot mottle virus (CfMV). ORF1 and ORF4 are predicted to encode single proteins. ORF2 is predicted to encode two proteins that are derived from a -1 translational frameshift between two overlapping reading frames (ORF2a and ORF2b). A search of amino acid databases did not find a significant match for ORF1 and the function of this protein remains unclear. ORF2a contains a motif typical of chymotrypsin-like serine proteases and ORF2b has motifs characteristically present in positive-stranded RNA-dependent RNA polymerases. ORF4 is likely to be expressed from a subgenomic RNA and encodes the viral coat protein. The ORF2a/ORF2b overlapping gene expression strategy used by SCMoV and CfMV is similar to that of the poleroviruses and differ from that of other published sobemoviruses. These results suggest that the sobemoviruses could now be divided into two distinct subgroups based on those that express the RNA-dependent RNA polymerase from a single, in-frame polyprotein, and those that express it via a -1 translational frameshifting mechanism.
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Affiliation(s)
- G I Dwyer
- Western Australian State Agricultural Biotechnology Centre, Division of Science and Engineering, Murdoch University, Perth, Australia.
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