First Report of Iris yellow spot virus Infection of Garlic and Egyptian Leek in Egypt

Egyptian leek (Allium ampeloprasum), garlic (A. sativum), and onion (A. cepa) are key vegetables produced by small- and large-scale farmers in Egypt for national and international markets. Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) is an economically important viral pathogen of bulb and seed onion crops in many onion-growing areas of the world (1,3). During February and March of 2011, symptoms of spindle-shaped, straw-colored, irregular lesions with occasional green islands were observed on onion, garlic, and Egyptian leek cultivated on large and small farms in Dakahlia, Gharbia, Kalubia, Menofia, Qena, and Assiut governorates in Egypt. The presence of IYSV was confirmed by specific double antibody sandwich (DAS)-ELISA Flash Kits (Agdia Inc., Elkhart, IN) (2). A survey was carried out by collecting 100 plant samples (10 asymptomatic and 90 symptomatic) of each plant species from fields in the governorates of Dakahlia, Gharbia, Kalubia, Menofia, Qena, and Assiute and testing the plants using DAS-ELISA. For onion and garlic, 45% of the symptomatic samples and 0% of the asymptomatic plants tested positive. For leek, 34% of the symptomatic samples tested positive and 0% of the asymptomatic samples. ELISA-positive samples were tested using a reverse transcription (RT)-PCR assay with primers specific to the S RNA of IYSV (forward primer 5′-TAAAACAAACATTCAAACAA-3′ and reverse primer 5′-CTCTTAAACACATTTAACAAGCAC-3′) (2). Amplicons of approximately 1,100 bp were obtained from all symptomatic samples that were ELISA positive, but none of the asymptomatic plants nor the sterile water control sample produced PCR amplicons. The amplicons were cloned (at least three clones per plant species) using the TOPO TA Cloning Kit (Invitrogen, Grand Island, NY), and sequenced. The Egyptian onion IYSV isolate (GenBank No. JN541273) had the greatest nucleotide sequence identity (86%) with the corresponding S RNA region of IYSV isolates from India (GenBank Nos. EU310290, EU310284, and EU310276). The Egyptian garlic IYSV isolate (GenBank No. JN541275) showed the strongest identity (93%) with that of a Sri Lankan IYSV isolate (GenBank No. GU901211). The Egyptian leek IYSV isolate (GenBank No. JN541274) exhibited 91% sequence identity with that of the same Sri Lankan isolate (No. GU901211). To our knowledge, this is the first report of IYSV infecting garlic and Egyptian leek in Egypt. IYSV infection of onion was reported previously from the agricultural farm of the Faculty of Agriculture, Cairo University, Giza (4), but to our knowledge, this is the first report of natural infection by the virus in commercial onion production in Egypt. Further surveys and monitoring of IYSV incidence and distribution in the entire Egyptian governorate are under investigation. References: (1) D. H. Gent et al. Plant Dis. 88:446, 2004. (2) H. R. Pappu et al. Arch. Virol. 151:1015, 2006. (3) H. R. Pappu et al. Virus Res. 141:219, 2009. (4) A. Manal et al. Egypt. J. Virol. 3:49, 2006.

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First Report of Iris yellow spot virus in Onion in Mauritius

Plant Disease ◽

10.1094/pdis-10-09-0645 ◽

2010 ◽

Vol 94 (11) ◽

pp. 1373-1373 ◽

Cited By ~ 5

Author(s):

K. Lobin ◽

A. Saison ◽

B. Hostachy ◽

S. P. Benimadhu ◽

H. R. Pappu

Keyword(s):

Disease Incidence ◽

Consensus Sequence ◽

Thrips Tabaci ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Spot Virus ◽

Viral Pathogen ◽

First Report ◽

Das Elisa

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) transmitted by thrips (Thrips tabaci Lindeman) is an economically important viral pathogen of bulb and seed onion (Allium cepa) crops in many onion-growing areas of the world (2,3). In Africa, IYSV has been reported in Reunion (4) and South Africa (1). In June 2008, diamond-shaped lesions that are typical of IYSV were observed on onion seed scapes in an onion plot of 0.25 ha at Reduit in the central part of Mauritius. Disease incidence was 80% with a severity of 50 to 75% of the scape surface area. Lodging was observed in 25% of the symptomatic plants. Twenty-two symptomatic plants were tested and found to be positive for IYSV when tested by double antibody sandwich (DAS)-ELISA with a commercially available kit (Agdia Inc., Elkhart, IN). The presence of the virus was confirmed by reverse transcription (RT)-PCR tests with primers 917L: 5′-TAAAACTTAACTAACACAAA-3′ and 56U: 5′-TCCTAAGTATTCACCAT-3′ as forward and reverse primers, respectively, for specific sequences flanking the CP gene. Another set of primers specific to the small (S) RNA of IYSV (5′-TAAAACAAACATTCAAACAA-3′ and 5′-CTCTTAAACACATTT AACAAGCAC-3′) produced an amplicon of approximately 1.2 kb that includes the 772-bp nucleocapsid (N) gene. The 1.2-kb amplicon was cloned and four clones were sequenced and consensus sequence was used for comparisons. Sequence analysis showed that the N gene of the IYSV isolate from Mauritius (GenBank Accession No. HM218822) shared the highest nucleotide sequence identity (99%) with several known IYSV N gene sequences (Accession Nos. FJ785835 and AM900393) available in the GenBank, confirming the presence of IYSV in the onion crops in Mauritius. A survey was subsequently carried out from July to November 2008 in major onion-growing localities at La Marie, Henrietta, Reduit, and Plaine Sophie (center); Bassin, La Ferme, and La Chaumiere (west); Grand Sable, Petit Sable, and Plaisance (south, southeast); and Belle Mare, Trou d'Eau Douce, and Palmar (east) to monitor the distribution of the disease on the island. Symptomatic samples with diamond-to-irregularly shaped lesions were observed and 155 symptomatic and 35 nonsymptomatic samples were collected and screened by DAS-ELISA for IYSV and Tomato spotted wilt virus (TSWV), another tospovirus reported to infect onion elsewhere. Sixty-six percent of the symptomatic samples screened (102 of 155) tested positive for IYSV. No IYSV was detected in the symptomless samples. There was no serological indication of TSWV infection in the samples. Samples that tested positive for IYSV were collected from Belle mare, Palmar, and Trou d'eau douce in the east and La Ferme in the west. Cultivars infected were Gandiole, Local Red, and Veronique. No IYSV was detected in the bulbs. The vector, T. tabaci, was observed in infected onion parcels surveyed and is known to occur in all onion-producing areas of the island. To our knowledge, this is the first report of IYSV in onion in Mauritius. Further surveys and monitoring of IYSV incidence, along with its impact on the yield, need to be established. References: (1) L. J. du Toit et al. Plant Dis. 91:1203, 2007. (2) D. H. Gent et al. Plant Dis. 88:446, 2004. (3) H. R. Pappu et al. Virus Res. 141:219, 2009. (4) I. Robène-Soustrade et al. Plant Pathol. 55:288, 2006.

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First Report of Iris yellow spot virus Infecting Onion in Kenya and Uganda

Plant Disease ◽

10.1094/pdis-01-11-0057 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1195-1195 ◽

Cited By ~ 7

Author(s):

R. Birithia ◽

S. Subramanian ◽

H. R. Pappu ◽

P. Sseruwagi ◽

J. W. Muthomi ◽

...

Keyword(s):

Sri Lanka ◽

Nucleotide Sequence ◽

Nucleotide Sequence Identity ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

Spot Virus ◽

Viral Pathogen ◽

First Report ◽

Sequence Identity ◽

Small Holder

Onion (Allium cepa L.) is one of the key vegetables produced by small-holder farmers for the domestic markets in Sub-Saharan Africa. Biotic factors, including infestation by thrips pests such as Thrips tabaci Lindeman, can inflict as much as 60% yield loss. Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) transmitted by T. tabaci is an economically important viral pathogen of bulb and seed onion crops in many onion-growing areas of the world (2,4). In Africa, IYSV has been reported in Reunion (1) and South Africa (3). In September 2009, symptoms suspected to be caused by IYSV were observed on onions and leeks cultivated in Nairobi, Kenya. Symptoms consisted of spindle-shaped, straw-colored, irregular chlorotic lesions with occasional green islands on the leaves. The presence of the virus was confirmed with IYSV-specific Agdia Flash kits (Agdia Inc., Elkart, IN). Subsequently, surveys were undertaken in small-holder farms in onion production areas of Makueni (January 2010) and Mwea (August 2010) in Kenya and Kasese (January 2010) and Rwimi (January 2010) in Uganda. The incidence of disease in these locations ranged between 27 and 72%. Onion leaves showing symptoms of IYSV infection collected from both locations tested positive for the virus by double-antibody sandwich-ELISA with IYSV-specific antiserum (Agdia Inc). IYSV infection was confirmed by reverse transcription-PCR with primers IYSV-465c: 5′-AGCAAAGTGAGAGGACCACC-3′ and IYSV-239f: 5′-TGAGCCCCAATCAAGACG3′ (3) as forward and reverse primers, respectively. Amplicons of approximately 240 bp were obtained from all symptomatic test samples but not from healthy and water controls. The amplicons were cloned and sequenced from each of the sampled regions. Consensus sequence for each isolate was derived from at least three clones. The IYSV-Kenya isolate (GenBank Accession No. HQ711616) had the highest nucleotide sequence identity of 97% with the corresponding region of IYSV isolates from Sri Lanka (GenBank Accession No. GU901211), followed by the isolates from India (GenBank Accession Nos. EU310287 and EU310290). The IYSV-Uganda isolate (GenBank Accession No. HQ711615) showed the highest nucleotide sequence identity of 95% with the corresponding region of IYSV isolates from Sri Lanka (GenBank Accession No. GU901211) and India (95% with GenBank Accession Nos. EU310274 and EU310297). To our knowledge, this is the first report of IYSV infecting onion in Kenya and Uganda. Further surveys and monitoring of IYSV incidence and distribution in the region, along with its impact on the yield, are under investigation. References: (1) L. J. du Toit et al. Plant Dis. 91:1203, 2007. (2) D. H. Gent et al. Plant Dis. 88:446, 2004. (3) H. R. Pappu et al. Plant Dis 92:588, 2008. (4) H. R. Pappu et al. Virus Res. 141:219, 2009.

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First Report of Iris yellow spot virus Infecting Onion in Pennsylvania

Plant Disease ◽

10.1094/pdis-03-12-0254-pdn ◽

2012 ◽

Vol 96 (8) ◽

pp. 1229-1229 ◽

Cited By ~ 1

Author(s):

C. A. Hoepting ◽

M. F. Fuchs

Keyword(s):

United States ◽

Nucleotide Sequence ◽

Nucleotide Sequence Identity ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Spot Virus ◽

First Report ◽

Sequence Identity ◽

Das Elisa

Iris yellow spot virus (IYSV; genus Tospovirus; family Bunyaviridae) is an economically important pathogen of onion. It is vectored by onion thrips (Thrips tabaci Lindeman) and causes widespread disease of onion in all major onion growing states in the western United States (1). In the eastern United States, IYSV was first reported in Georgia in 2004 (4) and then in New York in 2006 (2). In mid-July of 2010, symptomatic onion (Allium cepa) plants (cv. Candy) were found in New Holland, Pennsylvania, in Lancaster County on a small, diversified commercial farm (40.06°N, 76.06°W). Bleached, elongated lesions with tapered ends occurred on middle-aged leaves on approximately 30% of the 13,760 plants in an area approximately one tenth of an acre. Leaf tissue from five symptomatic plants tested positive for IYSV in a double-antibody sandwich (DAS)-ELISA with IYSV-specific serological reagents from Agdia Inc. (Elkhart, IN). A reverse transcription (RT)-PCR assay was used to verify the presence of IYSV in a subset of symptomatic leaf samples that reacted to IYSV antibodies in DAS-ELISA. Primers specific to the nucleocapsid (N) gene of IYSV (5′-ACTCACCAATGTCTTCAAC-3′ and 5′-GGCTTCCTCTGGTAAGTGC-3′) were used to characterize a 402-bp fragment (3). The resulting amplicons were ligated in TOPO TA cloning vector (Invitrogen, Carlsbad, CA) and two clones of each isolate were sequenced in both directions. Sequence analysis showed a consensus sequence for the partial N gene of the five IYSV isolates from Pennsylvania (GenBank Accession No. JQ952568) and an 87 to 100% nucleotide sequence identity with other IYSV N gene sequences that are available in GenBank. The highest nucleotide sequence identity (100%) was with an IYSV isolate from Texas (GenBank Accession No. DQ658242) and the lowest was with an isolate from India (GenBank Accession No. EU310291). To our knowledge, this is the first report of IYSV infection of onion in Pennsylvania. This finding confirms further spread of the virus within North America. Further study is warranted to determine the impact of IYSV on the Pennsylvania onion industry and to determine viable management strategies, if necessary. References: (1) D. H. Gent et al. Plant Dis. 88:446, 2004 (2) C. A. Hoepting et al. Plant Dis. 91:327, 2007 (3) C. L. Hsu et al. Plant Dis. 95:735-743. (4) S. W. Mullis et al. Plant Dis. 88: 1285, 2004.

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Natural Infection of Iris yellow spot virus in Twoscale Saltbush (Atriplex micrantha) Growing in Utah

Plant Disease ◽

10.1094/pdis-93-4-0430c ◽

2009 ◽

Vol 93 (4) ◽

pp. 430-430 ◽

Cited By ~ 7

Author(s):

C. K. Evans ◽

S. Bag ◽

E. Frank ◽

J. R. Reeve ◽

C. Ransom ◽

...

Keyword(s):

Natural Infection ◽

Sandwich Elisa ◽

The United States ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Nucleotide Sequence Analysis ◽

Jefferson County ◽

Spot Virus ◽

Sequence Identity

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) continues to be an economically important pathogen affecting onion bulb and seed production in several parts of the world and the United States (1). Several weeds were reported naturally infected with IYSV (1,2,4). Leaves of Atriplex micrantha Ledeb. (synonym A. heterosperma Bunge) were collected from naturally occurring plants in a weed trial conducted in commercial onions grown in Box Elder County, UT on 24 September 2008. Leaves displayed a range of symptoms including spotting, chlorosis, and necrosis. Symptomatic leaves were preferentially selected for subsequent diagnostic analyses. Samples were positive for IYSV when tested by double-antibody sandwich-ELISA using a commercially available kit (Agdia Inc., Elkhart, IN). For further confirmation, total nucleic acid extracts from the symptomatic parts of the leaves were prepared and tested for the presence of IYSV by reverse transcription-PCR with primers specific to the nucleocapsid (N) gene coded by the small (S)-RNA of IYSV. The forward and reverse primer pair, 5′-TCAGAAATCGAGAAACTT-3′ and 5′-CACCAATGTCTTCAACAATCTT-3′, respectively, amplifies a 751-nt fragment of the N gene (3). An amplicon of expected size was obtained, cloned, and sequenced. The nucleotide sequence analysis and comparison with known IYSV S-RNA sequences showed that the sequence of the amplicon from A. micrantha (GenBank Accession No. FJ493541) shared more than 84% nt sequence identity with the corresponding region of IYSV isolates available in GenBank, confirming the IYSV infection of the new host weed. The highest sequence identity (98%) was with an IYSV isolate from Jefferson County, OR (GenBank Accession No. DQ233479). To our knowledge, this is the first report of IYSV infection of A. micrantha under natural conditions. The role of A. micrantha and other weeds in IYSV epidemiology needs further investigation. References: (1) D. Gent et al. Plant Dis. 90:1468, 2006. (2) C. Nischwitz et al. Plant Dis. 91:1518, 2007. (3) H. R. Pappu et al. Arch. Virol. 151:1015, 2006. (4) R. Sampangi et al. Plant Dis. 91:1683, 2007.

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First Report of Iris yellow spot virus on Garlic in India

Plant Disease ◽

10.1094/pdis-94-8-1066c ◽

2010 ◽

Vol 94 (8) ◽

pp. 1066-1066 ◽

Cited By ~ 9

Author(s):

S. J. Gawande ◽

A. Khar ◽

K. E. Lawande

Keyword(s):

Natural Infection ◽

The United States ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Spot Virus ◽

First Report ◽

Qiagen Gmbh ◽

The World ◽

Seed Crops

Garlic (Allium sativum) is a spice crop of prime importance in India as well as other parts of the world. Iris yellow spot virus (IYSV; genus Tospovirus, family Bunyaviridae) is an important pathogen of onion bulb and seed crops in many parts of the world (3). The virus is also known to infect garlic and other Allium spp. (2–4). IYSV infection of garlic was reported from Reunion Island (4) and the United States (1). In February 2010, straw-colored, spindle-shaped spots with poorly defined ends were observed on the leaves of a garlic crop at the research farm of the Directorate of Onion and Garlic Research in the Pune District of Maharashtra State, India, 105 days after planting. The spots coalesced to form larger patches on the leaves, suggesting possible IYSV infection. Symptoms were visible on older leaves and more prevalent on cv. G-41, G-282, AC50, AC200, AC283, and Godavari than on other cultivars. The incidence of symptomatic plants was estimated at 5% for G-41 and AC-200, 8% for G-282 and AC283, and 10% for AC50. Leaves were sampled from 40 symptomatic plants per cultivar with each sample composited from young, middle, and older (basal) leaves of the plant. Samples were assayed by double-antibody sandwich-ELISA (Loewe Biochemica GmbH, Sauerlach, Germany) and each tested positive for the virus. Total RNA was extracted from the leaves of ELISA-positive plants using the RNAeasy Plant Mini kit (Qiagen GmbH, Hilden, Germany) and tested by reverse transcription-PCR assay using primers IYSV-F (5′-TCAGAAATCGAGAAACTT-3′) and IYSV-R (5′-TAATTATATCTATCTTTCTTGG-3′) (2) designed to amplify 797 bp of the nucleocapsid (N) gene of IYSV. Amplicons of expected size were obtained and cloned into a pDrive vector (Qiagen GmbH). The recombinant clone was sequenced (GenBank Accession No. HM173691). Sequence comparisons showed 98 to 100% nt identity with other IYSV N gene sequences in GenBank (Nos. EU310294 and EU310286). A phylogenetic analysis of the deduced amino acid sequences of the N gene showed that the garlic isolate of IYSV grouped most closely with onion IYSV isolates from India (GenBank Nos. EU310294, EU310286, EU310300, and EU310296). To our knowledge, this is the first report of natural infection of garlic by IYSV in India. Additional surveys and evaluations are needed to obtain a better understanding of the potential impact of IYSV on garlic production in India. References: (1) S. Bag et al. Plant Dis. 93:839, 2009. (2) A. Bulajic et al. Plant Dis. 93:976, 2009. (3) D. Gent et al. Plant Dis. 90:1468, 2006. (4) I. Robène-Soustrade et al. Plant Pathol. 55:288, 2006.

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First Report of Natural Infection of Garlic with Iris yellow spot virus in the United States

Plant Disease ◽

10.1094/pdis-93-8-0839a ◽

2009 ◽

Vol 93 (8) ◽

pp. 839-839 ◽

Cited By ~ 5

Author(s):

S. Bag ◽

P. Rogers ◽

R. Watson ◽

H. R. Pappu

Keyword(s):

United States ◽

Natural Infection ◽

Sandwich Elisa ◽

The United States ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Spot Virus ◽

Sequence Comparisons ◽

First Report

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) is an important constraint to onion bulb and seed production in several onion-growing regions of the United States (1,3). While garlic (Allium sativum) was reported to be infected with IYSV in Réunion Island (4), there have been no confirmed reports of natural infection of garlic in the United States. Garlic plants showing near-diamond-shaped lesions were found in August of 2008 in Marion County, Oregon. The 0.4046-ha (1-acre) field plot consisted of various true-seeded garlic varieties and was adjacent to three onion fields that showed IYSV symptoms. Symptoms were observed on 5% of the garlic plants with most of the symptomatic plants displaying small and diffuse straw-colored spots. Seven of these symptomatic plants were selected for testing. Of these, two showed characteristic diamond-shaped, elongated, straw-colored lesions on garlic scapes. However, the lesions were more diffuse with less-defined edges compared with the characteristic diamond-shaped lesions that are often associated with IYSV infection (1). All symptomatic plants were positive for IYSV by double-antibody sandwich-ELISA with a commercially available kit (Agdia Inc., Elkhart, IN). To verify IYSV infection, total nucleic acid extracts from the symptomatic parts of the leaves were prepared and tested for the presence of IYSV by reverse transcription (RT)-PCR with primers 5′-TAAAACAAACATTCAAACAA-3′ and 5′-CTCTTAAACACATTTAACAAGCAC-3′, which flank the nucleocapsid (N) gene coded by the small RNA of IYSV (2). An approximate 1.1-kb amplicon was obtained from all symptomatic plants and cloned and sequenced. Nucleotide sequence comparisons using BLAST showed that a consensus of three clones derived from the amplicon from garlic (No. FJ514257) was 85 to 99% identical with IYSV sequences available in GenBank (Nos. AF001387, AB180918, and AB286063), confirming the identity of IYSV. To our knowledge, this is the first report of natural infection of IYSV infection of garlic in the United States. Additional surveys and testing are needed to obtain a better understanding of IYSV incidence in garlic to evaluate its impact on garlic production. References: (1) D. Gent et al. Plant Dis. 90:1468, 2006. (2) H. R. Pappu et al. Arch. Virol. 151:1015, 2006. (3) H. R. Pappu et al. Virus Res. 141:219, 2009. (4) I. Robène-Soustrade et al. Plant Pathol. 55:288, 2006.

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First Report of Iris yellow spot virus Infecting Green Onion in Indonesia

Plant Disease ◽

10.1094/pdis-05-13-0503-pdn ◽

2013 ◽

Vol 97 (12) ◽

pp. 1665-1665 ◽

Cited By ~ 3

Author(s):

H. R. Pappu ◽

A. Rauf

Keyword(s):

Consensus Sequence ◽

Thrips Tabaci ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Spot Virus ◽

Viral Pathogen ◽

First Report ◽

Fta Cards ◽

Field Samples

Green onion (Allium fistulosum L.) is an important vegetable crop for small-holder farmers for domestic consumption in Indonesia. Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) transmitted by Thrips tabaci is an economically important viral pathogen of bulb and seed onion crops in many onion-growing areas of the world (1,3). In Asia, IYSV has been reported in India and Sri Lanka (2,4). In April 2013, symptoms suspected to be caused by IYSV were observed on a 1-month-old green onion crop grown for their leaves in a farmer's field in Cipendawa, Pacet, Cianjur District, West Java. Symptoms consisted of elliptical to spindle-shaped, straw colored, irregular, chlorotic lesions with occasional green islands on the leaves. Approximately 25% of the field had plants with these symptoms. The presence of the virus was confirmed with an IYSV-specific Agdia Flash kit. IYSV infection was confirmed by RT-PCR with primers specific to the nucleoprotein (N) gene of IYSV. Primers 465c: 5′-AGCAAAGTGAGAGGACCACC-3′ and IYSV-239f: 5′ TGAGCCCCAATCAAGACG3′ (3) were used as forward and reverse primers, respectively, using total nucleic acids eluted from FTA cards that were previously coated with freshly prepared sap extracts from field samples. Amplicons of approximately 240 bp were obtained from four symptomatic plants tested but not from healthy and water controls. The amplicons were cloned and sequenced. Consensus sequence was derived from three clones. Comparison with IYSV N gene sequences available in GenBank showed sequence identity of 95 to 99% confirming the identity of the virus as IYSV. To our knowledge, this is the first report of IYSV infecting onion in Indonesia. The finding in Java underscores the need for conducting surveys in Java as well as other onion-growing regions of Indonesia to gain a better understanding of its incidence, distribution, and potential impact. References: (1) D. H. Gent et al. Plant Dis. 88:446, 2004. (2) B. Mandal et al. Plant Dis. 96:468, 2012. (3) H. R. Pappu et al. Virus Res. 141:219, 2009. (4) K. S. Ravi et al. Plant Pathol. 55:288, 2006.

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First Report of Onion (Allium cepa) Naturally Infected with Iris yellow spot virus in Peru

Plant Disease ◽

10.1094/pd-90-0377a ◽

2006 ◽

Vol 90 (3) ◽

pp. 377-377 ◽

Cited By ~ 8

Author(s):

S. W. Mullis ◽

R. D. Gitaitis ◽

C. Nischwitz ◽

A. S. Csinos ◽

Z. C. Rafael Mallaupoma ◽

...

Keyword(s):

The United States ◽

Thrips Tabaci ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Enzyme Linked Immunosorbent Assay ◽

Spot Virus ◽

First Report ◽

The Impact ◽

Das Elisa

Onions have become an important export crop for Peru during the last few years. The onions produced for export are primarily short-day onions and include Grano- or Granex-type sweet onions. The first of two growing seasons for onion in Peru occurs from February/March until September/October and the second occurs from September/October to December/January. Iris yellow spot virus (IYSV [family Bunyaviridae, genus Tospovirus]), primarily transmitted by onion thrips (Thrips tabaci), has been reported in many countries during recent years, including the United States (1,2). In South America, the virus was reported in Brazil during 1999 (3) and most recently in Chile during 2005 (4). During 2003, an investigation of necrotic lesions and dieback in onions grown near the towns of Supe and Ica, Peru led to the discovery of IYSV in this region. Of 25 samples of symptomatic plants collected from five different fields near Supe, 19 tested strongly positive and an additional three tested weakly positive for IYSV using double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA) (Agdia Inc., Elkhart, IN). None of the samples tested positive for Tomato spotted wilt virus (TSWV). A number of onions with necrosis and dieback symptoms were also observed during 2004 and 2005. During September 2005, 25 plants with symptoms suspected to be caused by IYSV or TSWV in the Supe and Casma valleys were collected and screened for both viruses using DAS-ELISA. All plants screened were positive for IYSV. There was no serological indication of TSWV infection in these samples. The positive samples were blotted onto FTA cards (Whatman Inc., U.K.) to bind the viral RNA for preservation and processed according to the manufacturer's protocols. The presence of IYSV was verified by reverse transcription-polymerase chain reaction (RTPCR) using (5′-TCAGAAATCGAGAAACTT-3′) and (5′-TAATTATATCTATCTTTCTTGG-3′) as forward and reverse primers (1), respectively. The primers amplify the nucleocapsid (N) gene of IYSV, and the RT-PCR products from this reaction were analyzed with gel electrophoresis with an ethidium bromide stain in 0.8% agarose to verify the presence of this amplicon in the samples. Subsequent to the September 2005 sampling, 72 additional samples from regions in northern and southern Peru were analyzed in the same manner. The amplicons obtained were cloned, sequenced, and compared with known IYSV isolates for further verification. Onions have become a significant export crop for Peru, and more research is needed to determine the impact of IYSV on the Peruvian onion export crop. To our knowledge, this is the first report of IYSV in onion in Peru. References: (1) L. du Toit et al. Plant Dis. 88:222, 2004. (2) S. W. Mullis et al. Plant Dis. 88:1285, 2004. (3) L. Pozzer et al. Plant Dis. 83:345, 1999. (4) M. Rosales et al. Plant Dis. 89:1245, 2005.

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First Report of Iris yellow spot virus in Commercial Leek (Allium porrum) in Spain

Plant Disease ◽

10.1094/pdis-91-10-1365b ◽

2007 ◽

Vol 91 (10) ◽

pp. 1365-1365 ◽

Cited By ~ 5

Author(s):

C. Córdoba-Sellés ◽

C. Cebrián-Mico ◽

A. Alfaro-Fernández ◽

M. J. Muñoz-Yerbes ◽

C. Jordá-Gutiérrez

Keyword(s):

Natural Infection ◽

The United States ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Nucleotide Sequence Analysis ◽

Allium Porrum ◽

Rt Pcr ◽

Spot Virus ◽

First Report

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) has a wide host range, with onion (Allium cepa L.) being one of the most economically important hosts. The first report of IYSV in Spain was from Albacete in 2003 (1) followed by the Canary Islands in 2005. In November of 2006, disease symptoms suspected to be caused by IYSV were observed on the central and outer leaves of commercial leeks plants (cvs. Asthow, Edison, and Shelton) from Alicante, Spain. Symptoms consisted of dry, white-to-straw-colored, spindle-shaped, irregular chlorotic and necrotic lesions on the leaves. Tissue from symptomatic leaves was sampled and analyzed by a double-antibody sandwich (DAS)-ELISA with specific polyclonal antibodies against Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV) (Biorad Phyto-Diagnostics, Marnes-La Coquette, France), IYSV, and Tomato spotted wilt virus (TSWV) (Loewe Biochemica, Sauerlach, Germany). Five of seven leek samples belonging to the three cultivars tested were positive for IYSV. All samples were negative for the other viruses tested. The presence of IYSV was verified in the positive samples by reverse transcription (RT)-PCR using primers derived from the nucleocapsid (N) gene of IYSV (1). RT-PCR gave a PCR amplicon of expected size (approximately 790 bp) from symptomatic leek plants. The product of one of the positive leek samples was purified and sequenced (GenBank Accession No. EF427447). Nucleotide sequence analysis confirmed the identity of the amplicon as that of the IYSV N gene. Sequence comparisons showed 99% identity with the sequence of the IYSV Spanish isolate available in GenBank (Accession No. EF419888). Thrips tabaci is the primary vector of IYSV. Although the vector is present in Spain, the efficiency of the Mediterranean ecotype in transmitting the virus is not known. Leek has been reported to be a host of IYSV in countries such as the Netherlands, Reunion Island, Australia, and the United States (2). To our knowledge, this is the first report of natural infection of leek with IYSV in Spain. References: (1) C. Córdoba-Sellés et al. Plant Dis. 89:1243, 2005. (2) H. F. Schwartz et al. Plant Dis. 91:113, 2007.

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Identification of New Alternative Weed Hosts for Iris yellow spot virus in the Pacific Northwest

Plant Disease ◽

10.1094/pdis-91-12-1683b ◽

2007 ◽

Vol 91 (12) ◽

pp. 1683-1683 ◽

Cited By ~ 14

Author(s):

R. K. Sampangi ◽

S. K. Mohan ◽

H. R. Pappu

Keyword(s):

Plant Species ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

Onion Bulb ◽

N Gene ◽

Rt Pcr ◽

Weed Species ◽

Spot Virus ◽

Viral Pathogen ◽

Redroot Pigweed

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) is an economically important viral pathogen of onion bulb and seed crops in several parts of the United States and the world (1). IYSV is primarily transmitted by onion thrips (Thrips tabaci) and there is no evidence of seed transmission (1). However, susceptible cultivated and weed species could serve as reservoirs of inoculum from which thrips could acquire the virus to introduce and spread it in onion fields. Samples from asymptomatic and symptomatic volunteer onion plants in some of the commonly cultivated crops in the region (corn, wheat, grapes, mint, carrot, alfalfa, and sugar beets) and several common weeds in and around onion bulb and seed fields with a history of IYSV in Idaho and Washington were collected during the months of July, August, September and October of 2006. More than 175 samples from 35 plant species were analyzed for IYSV by a commercially available ELISA kit (Agdia Inc., Elkhart, IN). With the exception of a few volunteer onions, none of the other plant species had any symptoms of virus infection. Symptoms on volunteer onions included characteristic diamond-shaped lesions. To confirm the presence of IYSV in the ELISA-positive samples, total nucleic acids were extracted (2) and used in a reverse transcription (RT)-PCR assay (3). The primer pair consisted of 5′-TAA AAC AAA CAT TCA AAC AA-3′ and 5′-CTC TTA AAC ACA TTT AAC AAG CAC-3′. This primer pair flanks the nucleocapsid (N) gene of IYSV and generates an approximate 1.2-kb amplicon (3) that includes the complete N gene. An amplicon of expected size was obtained from each IYSV-positive sample. The amplicons were cloned and sequenced. There was a 95% sequence identity with known IYSV sequences. While several weed species gave ELISA values that suggested the presence of IYSV, results of RT-PCR assays failed to confirm the presence of the virus. This discrepancy between ELISA and RT-PCR results could be due to nonspecific reaction in ELISA (4) or difficulty associated with obtaining RT-PCR-quality templates for amplification. Only volunteer onions and the following weeds tested positive for IYSV by ELISA and RT-PCR: redroot pigweed (Amaranthus retroflexus), puncturevine (Tribulus terrestris), kochia (Kochia scoparia), prickly lettuce (Lactuca serriola), and common lambsquarters (Chenopodium album). Of these, redroot pigweed was recently reported to be ELISA-positive for IYSV (1). This information on the wider natural host range of IYSV, including potential alternative hosts that could serve as virus reservoirs, is useful for a better understanding of the disease epidemiology and in developing an integrated management strategy for reducing the impact of this disease. References: (1) D. Gent et al. Plant Dis. 90:1468, 2006. (2) H. R. Pappu et al. HortScience 40:697, 2005. (3) H. R. Pappu et al. Arch. Virol. 151:1015, 2006. (4) T. N. Smith et al. Plant Dis. 90:729, 2006.

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