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

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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First Report of Iris yellow spot virus on Onion (Allium cepa) in Texas

Plant Disease ◽

10.1094/pd-90-1359b ◽

2006 ◽

Vol 90 (10) ◽

pp. 1359-1359 ◽

Cited By ~ 7

Author(s):

M. E. Miller ◽

R. R. Saldana ◽

M. C. Black ◽

H. R. Pappu

Keyword(s):

Disease Incidence ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Nucleotide Sequence Analysis ◽

Rt Pcr ◽

Onion Thrips ◽

Spot Virus ◽

Das Elisa ◽

Bulb Yield

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) has emerged as a potentially devastating and widespread virus of onion. IYSV was first reported in the United States from Idaho in 1993 and has since spread to many of the onion-producing areas (1). In South America, the most recent reports of the virus on onion were from Peru and Chile (2,4). In 2005, onion plants in Uvalde County, Texas exhibited necrotic lesions on leaves typical of IYSV and disease incidence approached 100% in some fields with yield loss and quality problems. Five of six plants tested were positive for IYSV with double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA; Agdia Inc., Elkhart, IN). In 2006, similar lesions were observed on onion plants in Uvalde County and approximately 400 km south in Hidalgo and Cameron counties. Infection points generally started as a single plant near the edge of fields and spread to plants in a 3- to 4-m area after 1 to 2 weeks. Early-season disease incidence was low in onions grown for bulbs and transplants, <10% in 2006. Disease incidence increased in some fields until the crop was harvested. Leaves of symptomatic plants were tested for IYSV and Tomato spotted wilt virus (TSWV) using DAS-ELISA, and 18 of 23 samples from the Hidalgo County area and 12 of 21 samples from the Uvalde County area were positive for IYSV. All samples tested for TSWV from these counties were negative. Virus infection in some ELISA-positive plants was verified by reverse transcription-polymerase chain reaction (RT-PCR) using primers derived from the small RNA of IYSV. The primers flanked the IYSV nucleocapsid (N) gene (5′-TAA AAC AAA CAT TCA AAC AA-3′ and 5′-CTC TTA AAC ACA TTT AAC AAG CAC-3′ (3). RT-PCR gave a PCR product of expected size (approximately 1.2 kb). The DNA amplicon was cloned and sequenced (GenBank Accession No. DQ658242). Nucleotide sequence analysis confirmed the identity of the amplicon as that of IYSV N gene and sequence comparisons with known IYSV N gene sequences showed 95 to 98% sequence identity. The primary vector of IYSV, onion thrips (Thrips tabaci), is a widespread and destructive pest of onion in south Texas. The year-to-year incidence of IYSV and the severity of the disease will probably depend on the onion thrips population levels. Bulb yield reduction could be severe during years with high thrips populations. More research is needed to determine the impact of IYSV on bulb yield in Texas, the relationship between IYSV incidence and T. tabaci population levels, and oversummering hosts. To our knowledge, this is the first known report of IYSV in Texas. References: (1) D. H. Gent et al. Plant Dis. 88:446, 2004, (2) S. W. Mullis et al. Plant Dis. 90:377, 2006, (3) H. Pappu et al. Arch. Virol. 151:1015, 2006. (4) M. Rosales et al. Plant Dis. 89:1245, 2005.

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First Report of Iris yellow spot virus in Onion in Hawaii

Plant Disease ◽

10.1094/pdis-07-10-0531 ◽

2010 ◽

Vol 94 (12) ◽

pp. 1508-1508 ◽

Cited By ~ 4

Author(s):

D. M. Sether ◽

W. B. Borth ◽

R. S. Shimabuku ◽

H. R. Pappu ◽

M. J. Melzer ◽

...

Keyword(s):

United States ◽

New Zealand ◽

Phylogenetic Analyses ◽

Leaf Tissue ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Sequence Variants ◽

Rt Pcr ◽

Spot Virus

Onion (Allium spp.) production in Hawaii is mostly comprised of green onion and the locally prized sweet bulb onions (Allium cepa L.) that include short- and medium-day cultivars. Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) is an important constraint to bulb and seed onion production in many onion-growing regions of the continental United States and the world (3). In June 2010, straw-colored, diamond-shaped lesions with occasional green islands were observed on leaves of sweet onion ‘Linda Vista’ in an insecticide trial on Maui for onion thrips (Thrips tabaci) control. Collapse and lodging occurred when lesions on leaves were severe. Seven bulbs with green leaves exhibiting lesions were collected from this onion field in the Pulehu Region of the lower Kula District on Maui. Leaf samples that included a lesion or were within 1 cm of a lesion were found to be positive in indirect ELISA with IYSV-specific polyclonal antisera (2). A405nm readings after 1 h ranged from 0.263 to 2.067 for positive samples and 0.055 to 0.073 for healthy onion controls. Four samples that were prepared from leaf tissue several centimeters away from a lesion tested negative in ELISA. Such uneven virus distribution in the plants has been previously reported (4). In July 2010, symptomatic sweet onion from a commercial farm in upper Kula, Maui at the 1,060 to 1,220 m (3,500 to 4,000 foot) elevation tested positive for IYSV by ELISA. Green onion samples collected from a commercial farm in Omaopio, Maui, located approximately 0.8 km (0.5 mile) north of Pulehu, have tested negative, suggesting distribution may be limited at this time. RNA was isolated from leaf tissue from the seven ‘Linda Vista’ sweet onions collected from the Maui insecticide trial. Reverse transcription (RT)-PCR with forward and complementary primers 5′-CTCTTAAACACATTTAACAAGCAC-3′ and 5′-TAAAACAAACATTCAAACAA-3′ flanking the nucleocapsid (N) gene encoded by the small RNA of IYSV was conducted as previously described (1). Amplicons approximately 1.1 kb long were obtained from all seven symptomatic onion samples but not from healthy samples or water controls. Sequencing of selected amplicons confirmed IYSV infection. Three sequence variants (GenBank Accession Nos. HM776014–HM776016) were identified from two RT-PCR reactions. Phylogenetic analyses of the three sequence variants with the neighbor-joining procedure available through NCBI-BLASTn Tree View showed that the highest nucleotide identities of 97 to 98% were shared with IYSV isolates from New Zealand (EU477515), Nevada (FJ713699), and northern California (FJ713700). Phylogenetic analyses with the N-gene showed the sequences from Hawaii are most closely related to isolates from the western United States, Texas, and New Zealand. To date, to our knowledge, IYSV has not been detected on the islands of Kauai, Oahu, Molokai, or Hawaii. The distribution and economic consequences of this disease to Hawaii's onion production are under investigation. References: (1) H. R. Pappu et al. Arch Virol. 151:1015, 2006. (2) H. R. Pappu et al. Plant Dis. 92:588, 2008. (3) H. R. Pappu et al. Virus Res. 141:219, 2009. (4) T. N. Smith et al. Plant Dis. 90:729, 2006.

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Susceptibility of Onion Relatives (Allium spp.) to Iris yellow spot virus

Plant Disease ◽

10.1094/pdis-11-10-0819 ◽

2011 ◽

Vol 95 (10) ◽

pp. 1319-1319 ◽

Cited By ~ 1

Author(s):

C. S. Cramer ◽

S. Bag ◽

H. F. Schwartz ◽

H. R. Pappu

Keyword(s):

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Rt Pcr ◽

Sources Of Resistance ◽

Spot Virus ◽

Allium Species ◽

Elisa Kit ◽

Important Constraint ◽

Allium Cepa L

Iris yellow spot virus (IYSV; family Bunyaviridae, genus Tospovirus) is becoming an increasingly important constraint to the production of bulb and seed onions (Allium cepa L.) in many onion-growing regions of the continental United States and the world (4). During an evaluation of onion germplasm for susceptibility to IYSV, six other Allium species (A. altaicum, A. galanthum, A. roylei, A. schoenoprasum, A. tuberosum, and A. vavilovii) were also evaluated under natural field conditions. In July 2010, symptoms suggestive of IYSV infection (straw-colored necrotic lesions) were observed on leaves of these Allium spp. in experimental plots in Las Cruces, NM. IYSV was detected in symptomatic leaves of A. altaicum, A. vavilovii, A. tuberosum, A. schoenoprasum and A. roylei with a commercially available ELISA kit (Agdia Inc., Elkhart, IN). IYSV infection was confirmed by reverse transcription (RT)-PCR with forward and complementary primers 5′-CTCTTAAACACATTTAACAAGCAC-3′ and 5′-TAAAACAAACATTCAAACAA-3′ flanking the nucleocapsid (N) gene encoded by the small RNA of IYSV as previously described (1,3). Amplicons, approximately 1.1 kb long, were obtained from all symptomatic Allium spp. samples but not from healthy samples or water controls. Sequencing of selected amplicons confirmed IYSV infection. The highest nucleotide identity of 98% was shared with IYSV isolates from Japan (GenBank Accession No. AB180921). A. altaicum, A. vavilovii, and A. pskemense were previously reported from Washington to be susceptible to IYSV (2). Current findings expand the list of Allium spp. that are susceptible to IYSV and underscores the need for continued screening of other members of the genus to find sources of resistance to IYSV. References: (1) H. R. Pappu et al. Arch. Virol. 151:1015, 2006. (2) H. R. Pappu et al. Plant Dis. 90:378, 2006. (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 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 on Onion in New York

Plant Disease ◽

10.1094/pdis-91-3-0327a ◽

2007 ◽

Vol 91 (3) ◽

pp. 327-327 ◽

Cited By ~ 13

Author(s):

C. A. Hoepting ◽

H. F. Schwartz ◽

H. R. Pappu

Keyword(s):

United States ◽

New York ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Nucleotide Sequence Analysis ◽

Rt Pcr ◽

Onion Thrips ◽

Spot Virus ◽

First Report

Iris yellow spot virus (IYSV [family Bunyaviridae, genus Tospovirus]), a potentially devastating disease of onion vectored by onion thrips (Thrips tabaci Lindeman), has been reported from most states in the western United States where significant onion production occurs, with the most recent report from Texas (1). In June 2006, volunteer onion (Allium cepa) plants in Orleans County, New York (Elba muckland) were found to have symptoms indicative of IYSV infection. The scapes (seed stalks) of the volunteer onions found at the edge of a cull pile from a 2005 onion crop exhibited diamond-shaped lesions, each with a distinct green center and a double yellow border. Approximately 25 of 100 plants of red and yellow onion cultivars exhibited characteristic IYSV lesions. The cull pile was composed primarily of locally grown onions, although a few of the bulbs were grown from imported bare-root transplants imported from Arizona. Symptomatic plants tested positive for IYSV using IYSV-specific antiserum from Agdia Inc. (Elkhart, IN) in a double-antibody sandwich-ELISA. The presence of IYSV was verified by reverse transcription (RT)-PCR using primers derived from the small RNA of IYSV (S-RNA). The primers flanked the IYSV nucleocapsid (N) gene (5′-TAA AAC AAA CAT TCA AAC AA-3′ and 5′-CTC TTA AAC ACA TTT AAC AAG CAC-3′ (3). RT-PCR assays produced a PCR amplicon of expected size (approximately 1.2 kb) and the product was cloned and sequenced. Nucleotide sequence analysis confirmed the identity of the amplicon as that of the IYSV S-RNA. Sequence comparisons showed 95 to 98% identity with known IYSV N gene sequences available in GenBank. The virus is poorly transmitted to onion by mechanical inoculation and we did not have access to a noninfested colony of the onion thrips vector to transfer the virus from these samples to noninfected onions. No asymptomatic plants were tested. Among the onion-growing states in the eastern United States, IYSV has previously only been reported from Georgia (2). To our knowledge, this is the first report of IYSV in New York and the greater northeastern United States. The finding of this disease in New York confirms further spread of the virus within North America and the need for research to develop more effective management options to reduce the impact of IYSV on onion crops. References: (1) M. Miller et al. Plant Dis. 90:1359, 2006. (2) S. W. Mullis et al. Plant Dis. 90:377, 2006. (3) H. R. Pappu et al. Arch. Virol. 151:1015, 2006.

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Seasonal Dynamics of Thrips (Thrips tabaci) (Thysanoptera: Thripidae) Transmitters of Iris Yellow Spot Virus: A Serious Viral Pathogen of Onion Bulb and Seed Crops

Journal of Economic Entomology ◽

10.1603/ec13141 ◽

2014 ◽

Vol 107 (1) ◽

pp. 75-82 ◽

Cited By ~ 3

Author(s):

Sudeep Bag ◽

Silvia I. Rondon ◽

Keri L. Druffel ◽

David G. Riley ◽

Hanu R. Pappu

Keyword(s):

Seasonal Dynamics ◽

Thrips Tabaci ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

Onion Bulb ◽

Spot Virus ◽

Viral Pathogen ◽

Seed Crops

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First Report of Iris yellow spot virus in Commercial Leek (Allium porrum) in the United States

Plant Disease ◽

10.1094/pd-91-0113b ◽

2007 ◽

Vol 91 (1) ◽

pp. 113-113 ◽

Cited By ~ 5

Author(s):

H. F. Schwartz ◽

K. Otto ◽

H. R. Pappu

Keyword(s):

United States ◽

The United States ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

N Gene ◽

Allium Porrum ◽

Rt Pcr ◽

Spot Virus ◽

Disease Symptoms ◽

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. IYSV has been widely reported from this species throughout most onion-production regions of the United States and many areas of the world in recent years. A relative of onion, leek (Allium porrum L.), has been reported to be a host of IYSV in countries such as the Netherlands, Reunion Island, and Australia (1,4). A related tospovirus, Tomato spotted wilt virus (TSWV), was recently reported causing necrotic lesions and extended bleaching of leaf tips of leek in Georgia (2). In September of 2006, disease symptoms suspected to be caused by IYSV were observed on central and outer leaves of plants in a 2.6-ha section of commercial leeks being grown from seed (cvs. Tadorna and King Richard). The leek plants were adjacent to a 3.1-ha section of seeded onion (cv. Exacta) that had been harvested 2 weeks earlier. Twenty-five to thirty percent of unharvested onion plants next to the leek section also exhibited IYSV-type disease symptoms generally on the central leaves. Both Allium spp. were seeded 5 months earlier and grown under certified organic, pivot-irrigated conditions in Larimer County in northern Colorado. Disease symptoms on leek and onion leaves appeared as dry, white-to-straw-colored, spindle- or diamond-shaped lesions that ranged in size from 5 to 10 × 25 to 50 mm or larger depending on lesion age. Lesion centers, especially on leek, often had green centers with concentric rings of alternating green and straw-colored tissue. Green tissue near necrotic lesions of a single symptomatic leaf from 10 plants each of leek and onion was sampled and analyzed using a double-antibody sandwich (DAS)-ELISA (Agdia, Inc., Elkhart, IN). Five of ten leek and nine of ten onion samples were positive for IYSV. Using reverse transcription (RT)-PCR and primers specific to the small RNA of IYSV (5′-TAA AAC AAA CAT TCA AAC AA-3′ and 5′-CTC TTA AAC ACA TTT AAC AAG CAC-3′), the complete nucleocapsid (N) gene was amplified from symptomatic leek plants and then sequenced (3). Comparisons with IYSV N gene sequences available in the GenBank confirmed the identity of the virus as IYSV. Leek samples were negative for TSWV when tested by RT-PCR with TSWV-specific primers. In addition, three specimens of the presumed thrips vector recovered from five IYSV-infected leek plants were identified as Thrips tabaci (L. A. Mahaffey and W. S. Cranshaw, personal communication). Earlier in the season, T. tabaci was observed in the nearby planting of onion that also exhibited IYSV in September. To our knowledge, this is the first report of natural infection of commercial leek with IYSV in the United States. The incidence of plants (25 to 30%) with foliar lesions on multiple leaves and stunting of 5% of infected plants in both leek cultivars suggests that IYSV could seriously reduce leek stem development and marketability. References: (1) I. Cortes et al. Phytopathology 88:1276, 1998. (2) C. Nischwitz et al. Plant Dis. 90:525, 2006. (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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Symptomatology of Iris yellow spot virus in Selected Indicator Hosts

Plant Health Progress ◽

10.1094/php-2009-0824-01-br ◽

2009 ◽

Vol 10 (1) ◽

pp. 41 ◽

Cited By ~ 4

Author(s):

Sudeep Bag ◽

H. R. Pappu

Keyword(s):

Plant Species ◽

Biological Diversity ◽

Iris Yellow Spot Virus ◽

Yellow Spot ◽

Onion Bulb ◽

Mechanical Inoculation ◽

Spot Virus ◽

Seed Crops

Thrips-transmitted Iris yellow spot virus is an economically important pathogen of onion bulb and seed crops. To better understand the biological diversity of IYSV, several plant species were evaluated for their response to mechanical inoculation with IYSV under controlled greenhouse conditions. Accepted for publication 3 June 2009. Published 24 August 2009.

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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 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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