Spinach latent virus Infecting Tomato in Virginia, United States

Plants in a single field of commercial tomato (Solanum lycopersicum) of unidentified cultivars in Virginia in July, 2012, were observed showing stunting, leaf distortion, twisting and thickening, discoloration, and color streaking and ringspots on fruits. Serological tests were negative for Cucumber mosaic virus, Groundnut ringspot virus, Tomato spotted wilt virus, Tomato chlorotic spot virus, Impatiens necrotic spot virus, Tobacco mosaic virus, and Tomato bushy stunt virus (Agdia, Inc., Elkhart, IN). Using a membrane-based macroarray (3), hybridization was observed to 8 of 9 70-mer oligonucleotide probes of Spinach latent virus (SpLV; genus Ilarvirus, family Bromoviridae). To confirm the hybridization results, complementary DNA (cDNA) was synthesized using random hexamers and MMLV reverse transcriptase (Promega, Madison, WI), followed by PCR amplification using ilarvirus degenerate primers (4). Fragments of approximately 380 bp were amplified and directly sequenced (GenBank Accession KC_466090); a BLAST search showed a 99% identity to the SpLV RNA 2 reference genome (NC_003809). Primers for SpLV RNA1 (SpLVRNA1f-GGTGTCACCATGCAAACTGG, SpLVRNA1r-AGCTCTTCGTAATAGGCCTGC) and SpLV RNA3 (SpLVCPf-GAAGTCTTTCCCAGGTGAGCA, SpLVCPr-AGGTGGGCATATGGACTTGG) were designed and cDNA was amplified using the IQ supermix (Biorad, Hercules, CA) with thermocycling of 94°C for 4 min, 35× (94°C 45 s, 55°C 45 s, 72°C 45 s), and 72°C for 10 min. The resulting fragments of 538 bp for RNA1 (KC_466088) and 661 bp for RNA3 (KC_466089) showed 100% identity to reference genome sequences for SpLV (NC_003808 and NC_003810, respectively). To demonstrate virus transmissibility, Chenopodium quinoa plants were mechanically inoculated using tomato leaf material (same source described above) ground in 30 mM Na2HPO4 buffer, pH 7.0. Necrotic spots developed on the inoculated leaves 10 dpi. Younger, non-inoculated leaves showed yellow mottling and tested positive for SpLV by RT-PCR (two of two plants tested). The detection of SpLV is rarely reported, with only one record from the United States (2). Although SpLV is described as a latent virus, it has been found associated with tomato fruit symptoms in New Zealand (1). It is not known if the fruit ringspot and other symptoms on the Virginia samples were due to virus infection. Since SpLV is seed-transmissible and seed production takes place in different parts of the world, it has the potential to spread with germplasm and become more widespread in North America. References: (1) B. S. M. Lebas et al. Plant Dis. 91:228, 2007. (2) H. Y. Liu and J. E. Duffus. Phytopathology 76:1087, 1986. (3) K. L. Perry and X. Lu. Phytopathology 100:S100, 2010. (4) M. Untiveros, et al. J. Virol. Methods 165:97, 2010.

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First Report of Potato spindle tuber viroid Naturally Infecting Field Tomatoes in the Dominican Republic

Plant Disease ◽

10.1094/pdis-09-13-0992-pdn ◽

2014 ◽

Vol 98 (5) ◽

pp. 701-701

Author(s):

K.-S. Ling ◽

R. Li ◽

D. Groth-Helms ◽

F. M. Assis-Filho

Keyword(s):

United States ◽

Dominican Republic ◽

Mosaic Virus ◽

Potato Spindle Tuber Viroid ◽

The United States ◽

Disease Outbreak ◽

Ringspot Virus ◽

Rt Pcr ◽

Spot Virus ◽

Three Samples

In recent years, viroid disease outbreaks have resulted in serious economic losses to a number of tomato growers in North America (1,2,3). At least three pospiviroids have been identified as the causal agents of tomato disease, including Potato spindle tuber viroid (PSTVd), Tomato chlorotic dwarf viroid (TCDVd), and Mexican papita viroid (MPVd). In the spring of 2013, a severe disease outbreak with virus-like symptoms (chlorosis and plant stunting) was observed in a tomato field located in the Dominican Republic, whose tomato production is generally exported to the United States in the winter months. The transplants were produced in house. The disease has reached an epidemic level with many diseased plants pulled and disposed of accordingly. Three samples collected in May of 2013 were screened by ELISA against 16 common tomato viruses (Alfalfa mosaic virus, Cucumber mosaic virus, Impatiens necrotic spot virus, Pepino mosaic virus, Potato virus X, Potato virus Y, Tobacco etch virus, Tobacco mosaic virus, Tobacco ringspot virus, Tomato aspermy virus, Tomato bushy stunt virus, Tomato mosaic virus, Tomato ringspot virus, Tomato spotted wilt virus, Groundnut ringspot virus, and Tomato chlorotic spot virus), a virus group (Potyvirus group), three bacteria (Clavibacter michiganensis subsp. michiganensis, Pectobacterium atrosepticum, and Xanthomonas spp.), and Phytophthora spp. No positive result was observed, despite the presence of symptoms typical of a viral-like disease. Further analysis by RT-PCR using Agdia's proprietary pospiviroid group-specific primer resulted in positive reactions in all three samples. To determine which species of pospiviroid was present in these tomato samples, full-genomic products of the expected size (~360 bp) were amplified by RT-PCR using specific primers for PSTVd (4) and cloned using TOPO-TA cloning kit (Invitrogen, CA). A total of 8 to 10 clones from each isolate were selected for sequencing. Sequences from each clone were nearly identical and the predominant sequence DR13-01 was deposited in GenBank (Accession No. KF683200). BLASTn searches into the NCBI database demonstrated that isolate DR13-01 shared 97% sequence identity to PSTVd isolates identified in wild Solanum (U51895), cape gooseberry (EU862231), or pepper (AY532803), and 96% identity to the tomato-infecting PSTVd isolate from the United States (JX280944). The relatively lower genome sequence identity (96%) to the tomato-infecting PSTVd isolate in the United States (JX280944) suggests that PSTVd from the Dominican Republic was likely introduced from a different source, although the exact source that resulted in the current disease outbreak remains unknown. It may be the result of an inadvertent introduction of contaminated tomato seed lots or simply from local wild plants. Further investigation is necessary to determine the likely source and route of introduction of PSTVd identified in the current epidemic. Thus, proper control measures could be recommended for disease management. The detection of this viroid disease outbreak in the Dominican Republic represents further geographic expansion of the viroid disease in tomatoes beyond North America. References: (1). K.-S. Ling and M. Bledsoe. Plant Dis. 93:839, 2009. (2) K.-S. Ling and W. Zhang. Plant Dis. 93:1216, 2009. (3) K.-S. Ling et al. Plant Dis. 93:1075, 2009. (4) A. M. Shamloul et al. Can. J. Plant Pathol. 19:89, 1997.

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Helleborus net necrosis virus: A New Carlavirus Associated with ‘Black Death’ of Helleborus spp.

Plant Disease ◽

10.1094/pdis-93-4-0332 ◽

2009 ◽

Vol 93 (4) ◽

pp. 332-338 ◽

Cited By ~ 8

Author(s):

K. C. Eastwell ◽

L. J. du Toit ◽

K. L. Druffel

Keyword(s):

United States ◽

Mosaic Virus ◽

The United States ◽

Black Death ◽

Necrosis Virus ◽

Degenerate Primers ◽

The Family ◽

Net Necrosis ◽

Curved Rod ◽

Virus Isolates

Symptoms of ‘black death’ were observed on Helleborus spp. in each of three independent nurseries from across the United States. A new virus of the genus Carlavirus was identified in association with this disease. Symptomatic plants contained curved, rod-shaped particles averaging 800 by 17 nm, and yielded predominant bands of double-stranded (ds)RNA corresponding to approximately 9.0, 2.6, and 1.7 kbp. Amplification with degenerate primers for carlaviruses yielded a product of approximately 3,000 bp from diseased plants. Complete genomic sequences of two virus isolates were determined. Particle size, dsRNA patterns, genome organization, and sequence were consistent with members of the family Flexiviridae, genus Carlavirus. The name Helleborus net necrosis virus (HeNNV) is proposed for the virus associated with black death of Helleborus spp. in the United States. The sequence of the 3′ terminus of Helleborus mosaic virus (HeMV) (genus Carlavirus) was also determined. Nucleotide sequences of HeNNV and HeMV were only 49% identical, revealing the distinct nature of these viruses. Assays for other viruses failed to reveal a consistent association of any other virus with black death symptoms. Cucumber mosaic virus was detected in hellebore specimens both with and without distinct black death symptoms.

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First Report of Alternanthera mosaic virus Infection in Angelonia in the United States

Plant Disease ◽

10.1094/pdis-92-10-1473b ◽

2008 ◽

Vol 92 (10) ◽

pp. 1473-1473 ◽

Cited By ~ 7

Author(s):

B. E. Lockhart ◽

M. L. Daughtrey

Keyword(s):

United States ◽

Nucleotide Sequence ◽

Mosaic Virus ◽

Genomic Sequence ◽

Nutrient Deficiency ◽

Leaf Tissue ◽

The United States ◽

Nucleotide Sequence Analysis ◽

Degenerate Primers ◽

First Report

Stunting, chlorosis, and light yellow mottling resembling symptoms of nutrient deficiency were observed in angelonia (Angelonia angustifolia) in commercial production in New York. Numerous, filamentous particles 520 to 540 nm long and spherical virus particles 30 nm in diameter were observed by transmission electron microscopy (TEM) in negatively stained partially purified extracts of symptomatic Angelonia leaf tissue. Two viruses, the filamentous potexvirus Alternanthera mosaic virus (AltMV) and the spherical carmovirus Angelonia flower break virus (AnFBV) were subsequently identified on the basis of nucleotide sequence analysis of amplicons generated by reverse transcription (RT)-PCR using total RNA isolated from infected leaf tissue. A 584-bp portion of the replicase-encoding region of the AltMV genome was obtained with the degenerate primers Potex 2RC (5′-AGC ATR GNN SCR TCY TG-3′) and Potex 5 (5′-CAY CAR CAR GCM AAR GAT GA-3′) (3). Forward (AnFBV CP 1F-5′-AGC CTG GCA ATC TGC GTA CTG ATA-3′) and reverse (AnFBV CP 1R-5′-AAT ACC GCC CTC CTG TTT GGA AGT-3′) primers based on the published AnFBV genomic sequence (GenBank Accession No. NC_007733) were used to amplify a portion of the viral coat protein (CP) gene. The nucleotide sequence of the amplicon generated using the potexvirus-specific primers (GenBank Accession No. EU679362) was 99% identical to the published AltMV (GenBank Accession No. NC_007731) sequence and the nucleotide sequence of the amplicon obtained using the AnFBV CP primers was 99% identical to the published AnFBV genomic sequence (GenBank Accession No. EU679363). AnFBV occurs widely in angelonia (1) and AltMV has been identified in phlox (2). These data confirm the presence of AltMV and AnFBV in diseased angelonia plants showing stunting and nutrient deficiency-like symptoms and substantiates, to our knowledge, this first report of AltMV in angelonia in the United States. References: (1) S. Adkins et al. Phytopathology 96:460, 2006. (2) J. Hammond et al. Arch. Virol. 151:477, 2006. (3) R. A. A. van der Vlugt and M. Berendeson. Eur. J. Plant Pathol. 108:367, 2002.

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First Report of Cucumber mosaic virus in Anemone sp. in the United States

Plant Disease ◽

10.1094/pdis-93-4-0431b ◽

2009 ◽

Vol 93 (4) ◽

pp. 431-431 ◽

Cited By ~ 1

Author(s):

I. E. Tzanetakis

Keyword(s):

United States ◽

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Protein A ◽

The United States ◽

University Of Arkansas ◽

Degenerate Primers ◽

First Report ◽

Complete Coat Protein ◽

The University

In the spring of 2008, more than a dozen, aphid-infested, anemone plants (Anemone sp.) grown at the campus of the University of Arkansas in Fayetteville showed stunting and mosaic, whereas only two were asymptomatic. Leaf homogenates from four symptomatic plants were inoculated onto Nicotiana benthamiana that became stunted and developed severe mosaic approximately 7 days postinoculation, whereas buffer-inoculated plants remained asymptomatic. Double-stranded RNA (dsRNA) extraction (4) from symptomatic anemone revealed the presence of four predominant bands of approximately 3.2, 2.9, 2.2, and 0.9 kbp, a pattern indicative of cucumovirus infection. Cucumber mosaic virus (CMV) is the only cucumovirus reported in anemone in Europe (2) and Israel (3), and for this reason, anemone and N. benthamiana plants were tested by Protein A ELISA with antisera against CMV developed by H. A. Scott. ELISA verified the presence of CMV in symptomatic anemone and inoculated N. benthamiana, while asymptomatic plants were free of the virus. Using cucumovirus degenerate primers, essentially as described by Choi et al. (1), a region of approximately 940 bases that includes the complete coat protein gene of the virus was amplified from symptomatic anemone and N. benthamiana but not asymptomatic plants of either species. This anemone isolate (GenBank Accession No. FJ375723) belongs to the IA subgroup of CMV because it shares 99% nucleotide and 100% amino acid sequence identities with the Fny isolates of the virus. To my knowledge, this is the first report of CMV infecting anemone in the United States and an important discovery for the ornamental industry since anemone is commonly grown together with several ornamental hosts of CMV in nursery and garden settings. References: (1) S. K. Choi et al. J. Virol. Methods 83:67, 1999. (2) M. Hollings. Ann. Appl. Biol. 45:44, 1957 (3) G. Loebenstein. Acta Hortic. 722:31, 2006 (4) I. E. Tzanetakis and R. R. Martin, J. Virol. Methods 149:167, 2008.

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The Occurrence of Bean common mosaic virus and Cucumber mosaic virus in Yardlong Beans in Indonesia

Plant Disease ◽

10.1094/pdis-94-4-0478b ◽

2010 ◽

Vol 94 (4) ◽

pp. 478-478 ◽

Cited By ~ 4

Author(s):

T. A. Damayanti ◽

O. J. Alabi ◽

A. Rauf ◽

R. A. Naidu

Keyword(s):

United States ◽

Cucumber Mosaic Virus ◽

Mosaic Virus ◽

Disease Incidence ◽

The United States ◽

Bean Common Mosaic Virus ◽

Degenerate Primers ◽

Specific Primers ◽

Vein Clearing ◽

Yardlong Bean

Yardlong bean (Vigna unguiculata subsp. sesquipedalis) is extensively cultivated in Indonesia for consumption as a green vegetable. During the 2008 season, a severe outbreak of a virus-like disease occurred in yardlong beans grown in farmers' fields in Bogor, Bekasi, Subang, Indramayu, and Cirebon of West Java, Tanggerang of Banten, and Pekalongan and Muntilan of Central Java. Leaves of infected plants showed severe mosaic to bright yellow mosaic and vein-clearing symptoms, and pods were deformed and also showed mosaic symptoms on the surface. In cv. 777, vein-clearing was observed, resulting in a netting pattern on symptomatic leaves followed by death of the plants as the season advanced. Disease incidence in the Bogor region was approximately 80%, resulting in 100% yield loss. Symptomatic leaf samples from five representative plants tested positive in antigen-coated plate-ELISA with potyvirus group-specific antibodies (AS-573/1; DSMZ, German Resource Center for Biological Material, Braunschweig, Germany) and antibodies to Cucumber mosaic virus (CMV; AS-0929). To confirm these results, viral nucleic acids eluted from FTA classic cards (FTA Classic Card, Whatman International Ltd., Maidstone, UK) were subjected to reverse transcription (RT)-PCR using potyvirus degenerate primers (CIFor: 5′-GGIVVIGTIGGIWSIGGIAARTCIAC-3′ and CIRev: 5′-ACICCRTTYTCDATDATRTTIGTIGC-3′) (3) and degenerate primers (CMV-1F: 5′-ACCGCGGGTCTTATTATGGT-3′ and CMV-1R: 5′ ACGGATTCAAACTGGGAGCA-3′) specific for CMV subgroup I (1). A single DNA product of approximately 683 base pairs (bp) with the potyvirus-specific primers and a 382-bp fragment with the CMV-specific primers were amplified from ELISA-positive samples. These results indicated the presence of a potyvirus and CMV as mixed infections in all five samples. The amplified fragments specific to potyvirus (four samples) and CMV (three samples) were cloned separately into pCR2.1 (Invitrogen Corp., Carlsbad, CA). Two independent clones per amplicon were sequenced from both orientations. Pairwise comparison of these sequences showed 93 to 100% identity among the cloned amplicons produced using the potyvirus-specific primers (GenBank Accessions Nos. FJ653916, FJ653917, FJ653918, FJ653919, FJ653920, FJ653921, FJ653922, FJ653923, FJ653924, FJ653925, and FJ653926) and 92 to 97% with a corresponding nucleotide sequence of Bean common mosaic virus (BCMV) from Taiwan (No. AY575773) and 88 to 90% with BCMV sequences from China (No. AJ312438) and the United States (No. AY863025). The sequence analysis indicated that BCMV isolates from yardlong bean are more closely related to an isolate from Taiwan than with isolates from China and the United States. The CMV isolates (GenBank No. FJ687054) each were 100% identical and 96% identical with corresponding sequences of CMV subgroup I isolates from Thailand (No. AJ810264) and Malaysia (No. DQ195082). Both BCMV and CMV have been documented in soybean, mungbean, and peanut in East Java of Indonesia (2). Previously, BCMV, but not CMV, was documented on yardlong beans in Guam (4). To our knowledge, this study represents the first confirmed report of CMV in yardlong bean in Indonesia and is further evidence that BCMV is becoming established in Indonesia. References: (1) J. Aramburu et al. J. Phytopathol. 155:513, 2007. (2) S. K. Green et al. Plant Dis. 72:994, 1988. (3) C. Ha et al. Arch. Virol. 153:25, 2008. (4) G. C. Wall et al. Micronesica 29:101, 1996.

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First Report of Impatiens necrotic spot virus (INSV) Infecting Basil (Ocimum basilicum) in the United States

Plant Disease ◽

10.1094/pdis-11-12-1101-pdn ◽

2013 ◽

Vol 97 (6) ◽

pp. 850-850 ◽

Cited By ~ 5

Author(s):

S. Poojari ◽

R. A. Naidu

Keyword(s):

United States ◽

Nucleotide Sequence ◽

Nucleotide Sequence Identity ◽

The United States ◽

Ocimum Basilicum ◽

Impatiens Necrotic Spot Virus ◽

Necrotic Spot ◽

Rt Pcr ◽

Spot Virus ◽

Sequence Identity

Basil (Ocimum basilicum L.), a native of India belonging to the Lamiaceae family, is an aromatic herb with distinctive aroma, and several commercial varieties are used extensively for culinary and ornamental purposes. During the summer of 2011 and 2012, potted plants of basil in a commercial greenhouse in the Richland-Kennewick area of Washington State were observed showing foliar symptoms consisting of chlorotic spots, ring spots, leaf distortion, and stem necrosis. In initial tests, extracts of symptomatic leaves were positive for Impatiens necrotic spot virus (INSV; genus Tospovirus, family Bunyaviridae), when tested with INSV immnunostrips (Agdia, Inc., Elkhart, IN). These samples were negative with immunostrips specific to Tomato spotted wilt virus (genus Tospovirus) and group-specific potyviruses. The virus from symptomatic leaves of basil was transmitted by leaf rub inoculation to Nicotiana benthamiana and Emilia sonchifolia, where it produced necrosis on inoculated leaves followed by systemic necrosis in the former and chlorotic spots and mosaic mottling in newly developed leaves in the latter. Symptomatic leaves from both host plants tested positive with INSV, but not with TSWV, immunostrips. For additional confirmation of INSV, total RNA was extracted from symptomatic leaves of basil using RNeasy Plant Minikit (Qiagen, Inc., Valencia, CA) and used for reverse transcription (RT)-PCR amplification of the nucleocapsid (N) gene using forward (5′-AGCTTAAATCAATAGTAGCA-3′) and reverse (5′-AGCTTCCTCAAGAATAGGCA-3′) primers. RT was carried out at 52°C for 60 min followed by denaturation at 94°C for 3 min. Subsequently, 35 cycles of PCR was carried out with each cycle consisting of 94°C for 1 min, 58°C for 45 s, and 72°C for 1 min, followed by a final extension step at 72°C for 10 min. The amplicons of about 610 nt obtained from RT-PCR were cloned into pTOPO2.1 vector (Invitrogen Corporation, Carlsbad, CA) and three independent clones were sequenced in both directions. Sequence analyses of these clones (GenBank Accession No. KC218475) showed 100% nucleotide sequence identity among themselves and 99% nucleotide sequence identity with INSV isolates from the United States (DQ523598, JX138531, and D00914) and a basil isolate (JQ724132) from Austria. These results further confirm the presence of INSV in symptomatic leaves of basil. Previously, basil has been reported to be naturally infected with TSWV in the United States (3) and INSV in Austria (2). Therefore, this study represents the first confirmed report of the virus in basil in the United States. No species of thrips vector was observed on the affected basil plants. The discovery of INSV in basil has important implications for the nursery industry due to the broad host range of the virus (1); stock plants may serve as a source of inoculum in production areas and infected plants could be distributed to homeowners. It is important for commercial nurseries to monitor for INSV to identify infected mother plants to prevent virus spread. Since more than 31 viruses belonging to 13 different genera have been reported in basil ( http://pvo.bio-mirror.cn/famly073.htm#Ocimumbasilicum ), further studies are in progress to determine if the observed symptoms on basil are only due to single infection of INSV. References: (1) M. Daughtrey et al. Plant Dis. 81:1220, 1997. (2). S. Grausgruber-Gröger. New Dis. Rep. 26:12, 2012. (3) G. E. Holcomb et al. Plant Dis. 83:966.

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First Report of the Natural Infection of Coreopsis auriculata ‘Nana’ with Lettuce mosaic virus in the United States

Plant Disease ◽

10.1094/pdis-92-3-0486b ◽

2008 ◽

Vol 92 (3) ◽

pp. 486-486 ◽

Cited By ~ 1

Author(s):

R. A. Naidu ◽

G. Karthikeyan ◽

S. Jarugula ◽

M. Nelson ◽

A. Morrell

Keyword(s):

United States ◽

Mosaic Virus ◽

Natural Infection ◽

The United States ◽

Broad Host Range ◽

Native Plant ◽

Lettuce Mosaic Virus ◽

Degenerate Primers ◽

Eustoma Grandiflorum ◽

Conservation Projects

Perennial cultivars of Coreopsis, a genus native to the United States, are widely grown for aesthetics in home gardens and roadsides and are increasingly used in conservation projects and native-plant gardens. During the spring and summer of 2006 and 2007, Coreopsis auriculata ‘Nana’ plants with foliar symptoms showing chlorotic spots and rings were observed in wholesale and retail nurseries in Washington. Nicotiana benthamiana plants inoculated with crude sap extracts from symptomatic leaves of C. auriculata ‘Nana’ obtained from two different sources showed systemic mosaic mottling symptoms, indicating the presence of a virus. Symptomatic leaf samples from C. auriculata ‘Nana’ and N. benthamiana tested positive in antigen-coated plate-ELISA with potyvirus group-specific monoclonal antibodies (Agdia Inc., Elkhart, IN). Additional analysis by ELISA was positive for Lettuce mosaic virus (LMV; Agdia Inc.). To confirm these results, total RNA extracted from symptomatic N. benthamiana leaves was subjected to reverse transcription (RT)-PCR using potyvirus degenerate primers (PNIbF5: 5′-GCCAGCCCTCCACCGTNGTNGAYAA-3′ and PCPR1: 5′-GGGGAGGTGCCGTTCTCDATRCACCA-3′) covering the 3′ end of the NIb gene and the 5′ end of the CP gene (1). A single DNA band of approximately 1,000 bp amplified from symptomatic leaves of two independent plants was cloned separately into pCR2.1 (Invitrogen Corp., Carlsbad, CA). Two independent clones per amplicon were sequenced from both orientations. Pairwise comparison of these sequences with corresponding nucleotide sequences of potyviruses in GenBank showed 93 to 99% identity in the NIb/CP region with LMV sequences from France (GenBank Accession Nos. X97704, X65652, and X97705), China (GenBank Accession Nos. AJ306288 and AJ488153), and Brazil (GenBank Accession No. AJ278854). These results confirmed the presence of LMV in symptomatic leaves of N. benthamiana and C. auriculata ‘Nana’. The occurrence of LMV has been reported in ornamental plants that included freeway daisy (Osteospermum fruticosum), lisianthus (Eustoma grandiflorum), and gazanias (Gazania spp.) (2–4). To our knowledge, this is the first documented evidence for the occurrence of LMV in Coreopsis, an economically important perennial ornamental widely grown in the United States. Although the origin of LMV in C. auriculata ‘Nana’ is not known, distribution of cuttings from LMV-infected C. auriculata ‘Nana’ plants to wholesale and retailers within Washington and across the country by movement of plant material could pose a risk to other ornamentals and crops like lettuce because of the broad host range of LMV and its potential transmission by several species of polyphagous aphids. Seed transmission as a potential means of dissemination of LMV in Coreopsis has not been examined, although the virus is seedborne in other plants such as lettuce. References: (1) Y.-C. Hsu et al. J. Virol. Methods 128:54, 2005. (2) V. Lisa et al. Inf. Fitopatol. 3:58, 1995. (3). D. C. Opgenorth et al Plant Dis. 75:751, 1991. (4) F. M. Zerbini et al. Plant Dis. 81:641, 1997.

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First report of dasheen mosaic virus infecting taro (Colocasia esculenta) in Louisiana

Plant Disease ◽

10.1094/pdis-04-21-0854-pdn ◽

2021 ◽

Author(s):

Cesar Escalante ◽

David Galo ◽

Rodrigo Diaz ◽

Rodrigo Valverde

Keyword(s):

United States ◽

Mosaic Virus ◽

Consensus Sequence ◽

The United States ◽

Colocasia Esculenta ◽

Rt Pcr ◽

Serological Tests ◽

First Report ◽

Pcr Products ◽

The University

Taro [Colocasia esculenta (L.) Schott], also called dasheen or malanga is an important staple crop in many tropical and subtropical countries (Chaïr et al. 2016). In October 2020, taro plants showing foliar symptoms consisting of mosaic, feathery mottle, and vein clearing patterns were observed in the Hilltop Arboretum, the Bluebonnet Swamp Nature Center, the Louisiana State University Agricultural Center Botanic Gardens, and the University Lake, in Baton Rouge, Louisiana. Unidentified aphids were also observed infesting the plants showing the described symptoms. From each location, two foliar samples from symptomatic and two from asymptomatic plants were collected and tested by ELISA using antiserum for general potyvirus group (Agdia, Elkhart, IN). Seven of eight symptomatic samples tested positive while the asymptomatic samples were negative. The seven positive samples were used to perform an additional ELISA test using antiserum specific for dasheen mosaic virus (DsMV) (Agdia). All seven samples tested positive for DsMV. To confirm the identity of the virus, total RNA was extracted from the seven samples using the PureLink® Plant RNA Reagent Kit (Invitrogen, Carlsbad, CA). After DNA digestion with PerfeCta® DNase I (Qiagen, Beverly, MA), the RNA was used to perform reverse transcription polymerase chain reaction (RT-PCR) with primer set DMV 5708-5731-F/DMV 6131-6154-R which is specific for DsMV (Wang et al. 2017). RT-PCR was performed using the AccessQuickTM RT-PCR System (Promega, Madison, WI) following the reaction conditions described by Wang et al. PCR products of the expected size (~447 bp) were obtained with all seven samples and were Sanger-sequenced. A consensus sequence (MW284936) was obtained with the two sequences from samples collected at the University Lake and aligned with other sequences available in the GenBank using BLASTn. Our isolate of DsMV showed 90.6% nt identity to an isolate of DsMV from Ethiopia (MG602229). Mechanical inoculations to healthy taro plants were conducted using leaf tissue of symptomatic plants as source of inoculum. Inoculated plants exhibited mosaic symptoms three weeks after inoculation and were ELISA-positive for DsMV. Symptomatology, serological tests, RT-PCR testing, and DNA sequencing of RT-PCR products support that the symptomatic taro plants were infected with DsMV. Taro is a crop in Hawaii, but in the contiguous United States, it is mostly grown as an ornamental and is considered an invasive species. Its distribution is restricted to the southern continental states and Hawaii (Cozad et al. 2018). CABI, EPPO (1998) lists the presence of DsMV in several states of the United States, including Louisiana; however, there is no record in the literature of the identification of this virus in Louisiana. The potential impact of DsMV in taro and related ornamental species in southern United States is unknown. To the best of our knowledge, this is the first report documenting DsMV infecting taro in Louisiana.

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Characterization and Epidemiology of Outbreaks of Impatiens necrotic spot virus on Lettuce in Coastal California

Plant Disease ◽

10.1094/pdis-07-13-0681-re ◽

2014 ◽

Vol 98 (8) ◽

pp. 1050-1059 ◽

Cited By ~ 10

Author(s):

Yen-Wen Kuo ◽

Robert L. Gilbertson ◽

Tom Turini ◽

Eric B. Brennan ◽

Richard F. Smith ◽

...

Keyword(s):

United States ◽

Frankliniella Occidentalis ◽

Spinacia Oleracea ◽

Disease Outbreaks ◽

Central Valley ◽

The United States ◽

Impatiens Necrotic Spot Virus ◽

Necrotic Spot ◽

Weed Species ◽

Spot Virus

California is the leading producer of lettuce (Lactuca sativa) for the United States and grows 77% of the country's supply. Prior to 2006, coastal California lettuce was only periodically and incidentally infected by a single tospoviruses species: Tomato spotted wilt virus (TSWV). However, beginning in 2006 and continuing through 2012, severe outbreaks of disease caused by Impatiens necrotic spot virus (INSV) have affected the coastal lettuce crop, though TSWV was also present. In contrast, TSWV was the only tospovirus associated with disease outbreaks in Central Valley lettuce during this period. Disease surveys conducted over two seasons (2008 and 2009) in 10 commercial fields (acreage of 6 to 20 ha) indicated that INSV was the only tospovirus associated with economically damaging disease outbreaks in lettuce in the coastal region, with incidences of 0.5 to 27% (mean = 5.7%). Molecular characterization of INSV isolates associated with these disease outbreaks revealed little genetic diversity and indicated that lettuce-infecting INSV isolates were nearly identical to those previously characterized from ornamental or other hosts from different locations in the United States and the world. Monitoring of thrips revealed moderate to large populations in all surveyed lettuce fields, and the majority of thrips identified from these fields were western flower thrips, Frankliniella occidentalis. There was significant positive correlation (r2 = 0.91, P = 0.003) between thrips populations and INSV incidence in the most commonly encountered type of commercial lettuce (romaine, direct seeded, conventional) included in this study. A reverse-transcription polymerase chain reaction assay developed for detection of INSV in thrips showed promise as a monitoring tool in the field. Surveys for INSV reservoir hosts in the coastal production area revealed that the weeds little mallow (Malva parvifolia) and shepherd's purse (Capsella bursa-pastoris) were commonly infected. M. parvifolia plants infected in the field did not show obvious symptoms, whereas plants of this species inoculated in the laboratory with INSV by sap transmission developed necrotic spots and chlorosis. Eleven other weed species growing in the lettuce production areas were found to be hosts of INSV. Coastal crops found to be infected with INSV included basil (Ocimum basilicum), bell pepper (Capsicum annuum), calla lily (Zantedeschia aethiopica), faba bean (Vicia faba), radicchio (Cichorium intybus), and spinach (Spinacia oleracea). Thus, it is likely that INSV was introduced into coastal California lettuce fields via viruliferous thrips that initially acquired the virus from other local susceptible plant species. Results of this study provide a better understanding of INSV epidemiology in coastal California and may help growers devise appropriate disease management strategies.

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First Report of a New Potyvirus, Tricyrtis virus Y, and Lily virus X, a Potexvirus, in Tricyrtis formosana in the United States

Plant Disease ◽

10.1094/pdis-92-4-0648a ◽

2008 ◽

Vol 92 (4) ◽

pp. 648-648 ◽

Cited By ~ 3

Author(s):

R. L. Jordan ◽

M. A. Guaragna ◽

T. Van Buren ◽

M. L. Putnam

Keyword(s):

United States ◽

Amino Acid ◽

Mosaic Virus ◽

The United States ◽

Cdna Clones ◽

Gene Products ◽

Rt Pcr ◽

Degenerate Primers ◽

Specific Primers ◽

First Report

Tricyrtis formosana (toad lily) is an herbaceous perennial in the family Liliaceae. Native to Asia, T. formosana is now used in the United States as an ornamental border plant in woodland and shade gardens. A T. formosana var. stolonifera plant showing chlorosis and mild mosaic symptoms obtained from a commercial grower in Columbia County, Oregon tested positive for potyvirus by ELISA using our genus Potyvirus broad spectrum reacting PTY-1 Mab (3). Electron microscopic examination of negatively stained leaf-dip preparations from symptomatic leaves showed a mixture of two sizes of flexuous rod-shaped particles, approximately 700 nm long (resembling potyviruses) and 470 nm long (resembling potexviruses). Total RNA extracts from symptomatic leaves were used in reverse transcription (RT)-PCR assays with potyvirus- or potexvirus-specific primers. The degenerate primers for the genus Potyvirus (2) direct the amplification of approximately 1,600-bp fragments from the 3′ terminus of most potyviruses. Overlapping potexvirus cDNA clones were generated using degenerate genus Potexvirus replicase primers, and later, virus-specific primers in 3′ RACE (4). The RT-PCR amplified fragments were cloned and sequenced. Analysis of the 1,688 nt potyvirus sequence (GenBank Accession No. AY864850) using BLAST showed highest identity with members of the Bean common mosaic virus (BCMV) subgroup of potyviruses. Pairwise amino acid comparisons of the CP region of the new potyvirus showed 78% identity to strains of Bean common mosaic necrosis virus, 77% identity with Soybean mosaic virus and Ceratobium mosaic virus, 72 to 76% identity to strains of BCMV, and only 50 to 64% identity with 54 other potyviruses. Additionally, similar pairwise analysis of the CP nucleotide sequence and 3′NCR of the new potyvirus generally revealed the same identity trend as described for the CP amino acid sequences, albeit with the highest nucleotide identities at less than 73% for CP and less than 66% for the 3′NCR. These results suggest that this virus is a new species in the genus Potyvirus (1), which we have tentatively named Tricyrtis virus Y (TrVY). BLAST analysis of the 3′ terminal 3,010 nt potexvirus sequence (GenBank Accession No. AY864849) showed 89% nucleotide identity with Lily virus X (LVX). Pairwise amino acid comparisons of the putative gene products revealed 98, 95, 94 and 99% identity with LVX TGBp1, TGBp2, TGBp3-like, and CP, respectively, and 97% identity with the 108 nt 3′NCR. Homology with other members of the genus Potexvirus was less than 50% for these corresponding genes and gene products. ELISA and RT-PCR analysis for these two viruses in toad lily plants obtained from a grower in Illinois also revealed the presence of TrVY in three of seven cultivars and LVX coinfecting only one of the plants. The standard propagation method for T. formosana is plant division, which along with mechanical contact, provides efficient means for spread of both viruses. To our knowledge, this is the first description of this potyvirus and the first report of any potyvirus in T. formosana. LVX has been reported in Lilium formosanum, but to our knowledge, this is also the first report of LVX in T. formosana. References: (1) P. H. Berger et al. Potyviridae. Page 819 in: Virus Taxonomy: 8th Rep. ICTV, 2005. (2) M. A. Guaragna et al. Acta. Hortic. 722:209, 2006. (3) R. L. Jordan and J. Hammond. J. Gen. Virol. 72:1531, 1991. (4) C. J. Maroon-Lango et al. Arch. Virol. 150:1187, 2005.

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