title: RNA interference-based resistance in transgenic tomato plants against Tomato yellow leaf curl virus-Oman (TYLCV-OM) and its associated betasatellite.
abstract: BACKGROUND
  Tomato yellow leaf curl virus (TYLCV), a monopartite begomovirus (family Geminiviridae) is responsible for heavy yield losses for tomato production around the globe. In Oman at least five distinct begomoviruses cause disease in tomato, including TYLCV. Unusually, TYLCV infections in Oman are sometimes associated with a betasatellite (Tomato leaf curl betasatellite [ToLCB]; a symptom modulating satellite). RNA interference (RNAi) can be used to develop resistance against begomoviruses at either the transcriptional or post-transcriptional levels.
  
  
  RESULTS
  A hairpin RNAi (hpRNAi) construct to express double-stranded RNA homologous to sequences of the intergenic region, coat protein gene, V2 gene and replication-associated gene of Tomato yellow leaf curl virus-Oman (TYLCV-OM) was produced. Initially, transient expression of the hpRNAi construct at the site of virus inoculation was shown to reduce the number of plants developing symptoms when inoculated with either TYLCV-OM or TYLCV-OM with ToLCB-OM to Nicotiana benthamiana or tomato. Solanum lycopersicum L. cv. Pusa Ruby was transformed with the hpRNAi construct and nine confirmed transgenic lines were obtained and challenged with TYLCV-OM and ToLCB-OM by Agrobacterium-mediated inoculation. For all but one line, for which all plants remained symptomless, inoculation with TYLCV-OM led to a proportion (≤25%) of tomato plants developing symptoms of infection. For inoculation with TYLCV-OM and ToLCB-OM all lines showed a proportion of plants (≤45%) symptomatic. However, for all infected transgenic plants the symptoms were milder and virus titre in plants was lower than in infected non-transgenic tomato plants.
  
  
  CONCLUSIONS
  These results show that RNAi can be used to develop resistance against geminiviruses in tomato. The resistance in this case is not immunity but does reduce the severity of infections and virus titer. Also, the betasatellite may compromise resistance, increasing the proportion of plants which ultimately show symptoms.
authors.affiliation: Department of Crop Sciences, College of Agriculture and Marine Sciences, Sultan Qaboos University, P.O. Box-34, 123, Al-Khod, Oman. ammarajawad@gmail.com.
authors.forename: Um e
authors.initials: Ue
authors.lastname: Ammara
authors.affiliation: Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan. shahidmansoor7@gmail.com.
authors.forename: Shahid
authors.initials: S
authors.lastname: Mansoor
authors.affiliation: Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan. saeed_hafeez@yahoo.com.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Saeed
authors.affiliation: Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan. imranamin1@yahoo.com.
authors.forename: Imran
authors.initials: I
authors.lastname: Amin
authors.affiliation: Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan. rob.briddon@gmail.com.
authors.forename: Rob W
authors.initials: RW
authors.lastname: Briddon
authors.affiliation: Department of Crop Sciences, College of Agriculture and Marine Sciences, Sultan Qaboos University, P.O. Box-34, 123, Al-Khod, Oman. alsadi@squ.edu.om.
authors.forename: Abdullah Mohammed
authors.initials: AM
authors.lastname: Al-Sadi
mesh_terms: D053839:Begomovirus / Q000235:genetics* / Q000502:physiology; D018551:Solanum lycopersicum / Q000235:genetics / Q000276:immunology / Q000821:virology*; D009850:Oman; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000517:prevention & control / Q000821:virology*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000276:immunology / Q000821:virology*; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D012526:Satellite Viruses / Q000235:genetics* / Q000502:physiology
chemical_list: D012330:RNA, Double-Stranded; D012367:RNA, Viral