Skip to main content
ARS Home » Research » Publications at this Location » Publication #262032
Title: Newly discovered natural hosts of tomato chlorosis virus in Costa Rica

Author
item SOLOZANO-MORALES, A - Universidad De Costa Rica
item BARBOZA, N - Universidad De Costa Rica
item HERNANDEZ, E - Universidad De Costa Rica
item MORA-UMANA, F - Universidad De Costa Rica
item RAMIREZ, P - Universidad De Costa Rica
item Hammond, Rosemarie

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2011
Publication Date: 4/1/2011
Citation: Solozano-Morales, A., Barboza, N., Hernandez, E., Mora-Umana, F., Ramirez, P., Hammond, R. 2011. Newly discovered natural hosts of tomato chlorosis virus in Costa Rica. Plant Disease. 95:497.

Interpretive Summary: Tomato chlorosis virus (ToCV) is an emerging whitefly-transmitted crinivirus. In early 2007, severe yellowing and chlorosis were observed in field-grown tomatoes in Costa Rica. In 2008 and 2009, studies were conducted by an ARS scientist in Beltsville, Maryland and collaborators in Costa Rica to determine if weeds could also serve as reservoirs for the virus. Results of molecular analyses revealed that ToCV was present in common weeds adjacent to tomato nurseries. This is the first report of these weeds as natural hosts of ToCV in Costa Rica. This information has been communicated to growers in Costa Rica and is being used to assess the incidence of the virus in weeds and the economic impact on tomato production. The results impact U.S. agriculture as ToCV is emerging as a serious threat to tomato production in North America.

Technical Abstract: Tomato chlorosis virus (ToCV) is an emerging whitefly-transmitted crinivirus. ToCV was detected in field-grown and greenhouse tomato (Solanum lycopersicum L.) plants in Costa Rica in 2007, causing symptoms of severe yellowing and foliar chlorosis. To identify alternative hosts that may serve as virus reservoirs, 78 samples were collected from multiple species of common weeds growing adjacent to tomato nurseries in the Cartago province, where ToCV was previously identified, during the autumn of 2008 and summer of 2009. The weeds were collected based on the presence of whiteflies and/or symptoms of interveinal chlorosis, but not all samples were obviously symptomatic for infection by ToCV. Total RNA was extracted from leaf tissue using TRI Reagent (Molecular Research Inc., Cincinnati, OH). Reverse transcription (RT)-PCR reactions were performed using the Qtaq One-Step qRT-PCR SYBR® kit (Clontech Laboratories, Mountain View, CA) and primers specific for the ToCV HSP70h gene. A 123-bp DNA fragment was amplified in six weeds, which were identified taxonomically as Ruta chalepensis (Rutaceae), Cucurbita moschata (Cucurbitaceae), Phytolacca icosandra (Phytolacaceae), Plantago major (Plantaginaceae) and Brassica sp. (Brassicaceae) (two samples). The amplified DNA fragments were sequenced and BLAST analysis showed 100% identity with the HSP70h gene of the Florida ToCV isolate (GenBank Accession No. AY903448). To confirm the presence of ToCV in these six weed samples, conventional RT-PCR reactions were performed using primers specific for the ToCV CPm and p22 genes as described previously. Nucleotide sequence analysis of the amplified DNA fragments verified their identity as ToCV, with 100% sequence identity to the CPm of ToCV isolate of Florida (Accession no. AY903448) and the p22 gene of the Cartago, Costa Rican isolate (Accession no. FJ809714). Although the number of samples analyzed is not sufficient to allow a determination of the role of weed reservoirs in ToCV epidemics in Costa Rican tomato crops, our report on the wider natural host range of ToCV in Costa Rica is useful for a better understanding of the epidemiology of this virus and for developing disease management strategies. To our knowledge this is the first report of these weeds as natural hosts of ToCV.