scholarly journals (251) Screening Spring-seeded Onion Cultivars for Iris Yellow Spot Virus

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1047A-1047
Author(s):  
Parminder Singh Multani ◽  
Christopher S. Cramer

Identification of resistant cultivars offers the best control for Iris yellow spot virus (IYSV), a new onion disease vectored by Thrips tabaci. In this study, 18 spring-seeded onion cultivars were screened for IYSV. Each alternate plot in the field was planted with infected bulbs from the previous year to serve as a source of virus inoculum and thrips. With increased thrips population and temperature over time, straw-colored, necrotic lesions typical to IYSV infection were observed on plant leaves. Plants were analyzed by enzyme linked immunosorbant assay to confirm the IYSV infection and determine the virus titer. Ten randomly selected plants from each plot were rated for IYSV symptoms on a scale of 1 to 9, with 1 representing no symptomatic tissue and 9 representing more than 50% tissue damage. Starting 1 June, disease ratings were collected each week until 13 July. Nearly all cultivars showed similar disease symptoms when rated on 1 June. By 29 June, NMSU 03-52-1 exhibited some tolerance to IYSV as fewer symptoms were observed. By 13 July, NMSU 03-52-1 exhibited fewer disease symptoms than most of the other cultivars tested, while `Caballero' showed the highest IYSV symptoms. All other cultivars showed low to high susceptibility for IYSV. The increase in disease severity was accompanied by a relative increase in the virus titer of plants over time. However, virus titer poorly correlated with the amount of disease symptoms in different cultivars. The most tolerant cultivar, NMSU 03-52-1, had higher virus titer than many susceptible cultivars but still performed well. Conversely, some cultivars with low virus titer were susceptible and developed more symptoms. This indicates a difference in the capabilities of different cultivars to resist IYSV.

HortScience ◽  
2009 ◽  
Vol 44 (3) ◽  
pp. 627-632 ◽  
Author(s):  
Parminder S. Multani ◽  
Christopher S. Cramer ◽  
Robert L. Steiner ◽  
Rebecca Creamer

Identification of resistant or tolerant onion (Allium cepa L.) cultivars is crucial for the development of integrated management strategies for Iris yellow spot virus (IYSV). Exclusively vectored by onion thrips (Thrips tabaci), IYSV is a potentially devastating tospovirus of onion that has been confirmed to be present in 15 countries all over the world. In this study, 18 winter-sown onion entries were screened for IYSV symptom expression over two seasons. Over the growing season, straw-colored, necrotic lesions typical of IYSV infection were observed and rated for disease severity. Entries, NMSU 03-52-1, NMSU 04-41, NMSU 04-44-1, and ‘NuMex Jose Fernandez’, exhibited fewer symptoms than many other entries tested. ‘Caballero’, NMSU 04-57-1, NMSU 04-78-1, and ‘Cimarron’ exhibited more symptoms. Disease progression over time was rapid for entries exhibiting more symptoms and slow for entries exhibiting fewer symptoms. Enzyme-linked immunosorbent assay (ELISA) optical densities correlated poorly with the severity of disease symptoms. Trends in the disease progression over time emphasize the importance of rating IYSV symptoms late in the crop's development and to search for delayed disease progression rather than early symptom expression to determine IYSV susceptibility.


Plant Disease ◽  
2004 ◽  
Vol 88 (9) ◽  
pp. 1049-1049 ◽  
Author(s):  
R. Creamer ◽  
S. Sanogo ◽  
A. Moya ◽  
J. Romero ◽  
R. Molina-Bravo ◽  
...  

Onions are an important crop for New Mexico with 7,700 acres (3,116 ha) harvested in the state in 2003 (3). In 2002, onions of several cultivars were first noticed with diamond-shaped chlorotic or bleached lesions on seed stalks or leaves, typical of those reported for Iris yellow spot virus (IYSV). A more widespread survey of breeding stocks and commercial onion fields revealed similar symptoms on thrips-infested onions in Dona Ana and Rio Arriba counties. Incidence of disease symptoms ranged from <0.5 to nearly 30%. Symptomatic leaves were assayed for the presence of IYSV using enzyme-linked immunosorbent assay (ELISA; Agdia, Elkhart, IN) and antisera acquired from Agdia. Symptomatic leaves from breeding and commercial fields tested positive for IYSV. The virus was transmitted by Thrips tabaci from symptomatic onions to three onion cvs. New Mex Mesa, New Mex Vado, and New Mex Cryspy in growth chamber tests. All three cultivars showed symptoms of IYSV and tested positive for the disease using ELISA. However, New Mex Vado and New Mex Cryspy cultivars each showed 24% infection (4 infected plants of 17 tested) compared with 59% infection (10 infected plants of 17 tested) for New Mex Mesa, suggesting that not all cultivars are equally susceptible to the virus. To our knowledge, this is the first report of IYSV in onions in New Mexico, which has also been reported in the western United States in Idaho, Oregon, Colorado, and Washington (1,2,4). References: (1) L. J. du Toit et al. Plant Dis. 88:222, 2004. (2) J. M. Hall et al. Plant Dis. 77:952, 1993. (3) National Agricultural Statistics Service, On-line publication. USDA, 2004. (4) H. F. Schwartz et al. Plant Dis. 86:560, 2002.


2012 ◽  
Vol 105 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Rajagopalbabu Srinivasan ◽  
Sivamani Sundaraj ◽  
Hanu R. Pappu ◽  
Stan Diffie ◽  
David G. Riley ◽  
...  

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 838-842 ◽  
Author(s):  
A. Kritzman ◽  
M. Lampel ◽  
B. Raccah ◽  
A. Gera

Iris yellow spot virus (IYSV), a new tospovirus associated with a disease in onion (Allium cepa) that is known to growers in Israel as “straw bleaching,” was identified and further characterized by host range, serology, electron microscopy, and molecular analysis of the nucleocapsid gene. The transmissibility of IYSV by Thrips tabaci and Frankliniella occidentalis was studied. IYSV was efficiently transmitted by T. tabaci from infected to healthy onion seedlings and leaf pieces. Two biotypes of F. occidentalis, collected from two different locations in Israel, failed to transmit the virus. Surveys to relate the incidence of thrips populations to that of IYSV were conducted in onion fields. They revealed that the onion thrips T. tabaci was the predominant thrips species, and that its incidence was strongly related to that of IYSV. Forty-five percent of the thrips population collected from IYSV-infected onion and garlic fields in Israel transmitted the virus. IYSV was not transmitted to onion seedlings from infected mother plants through the seed, and was not located in bulbs of infected plants.


Plant Disease ◽  
2010 ◽  
Vol 94 (11) ◽  
pp. 1373-1373 ◽  
Author(s):  
K. Lobin ◽  
A. Saison ◽  
B. Hostachy ◽  
S. P. Benimadhu ◽  
H. R. Pappu

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.


Author(s):  

Abstract A new distribution map is provided for Iris yellow spot virus, Bunyaviridae: Tospovirus. Hosts: onion (Allium cepa), Dutch iris (Iris hollandica), leek (Allium porrum) and Hippeastrum spp. Information is given on the geographical distribution in Europe (France, Mainland France, Germany, Italy, Mainland Italy, Netherlands, Poland, Serbia, Slovenia, Spain, Mainland Spain, UK, England and Wales), Asia (India, Maharashtra, Iran, Israel, Japan, Honshu, Kyushu), Africa (Reunion, South Africa, Tunisia), North America (Canada, Ontario, USA, Arizona, California, Colorado, Georgia, Idaho, Nevada, New Mexico, New York, Oregon, Texas, Utah, Washington), Central America and Caribbean (Guatemala), South America (Brazil, Pernambuco, Sao Paulo, Chile, Peru), Oceania (Australia, New South Wales, Victoria, Western Australia, New Zealand). It is vectored by Thrips tabaci (Thysanoptera: Thripidae).


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