title: RNA silencing-mediated resistance to a crinivirus (Closteroviridae) in cultivated sweet potato (Ipomoea batatas L.) and development of sweet potato virus disease following co-infection with a potyvirus.
abstract: Sweet potato chlorotic stunt virus (SPCSV; genus Crinivirus, family Closteroviridae) is one of the most important pathogens of sweet potato (Ipomoea batatas L.). It can reduce yields by 50% by itself and cause various synergistic disease complexes when co-infecting with other viruses, including sweet potato feathery mottle virus (SPFMV; genus Potyvirus, family Potyviridae). Because no sources of true resistance to SPCSV are available in sweet potato germplasm, a pathogen-derived transgenic resistance strategy was tested as an alternative solution in this study. A Peruvian sweet potato landrace 'Huachano' was transformed with an intron-spliced hairpin construct targeting the replicase encoding sequences of SPCSV and SPFMV using an improved genetic transformation procedure with reproducible efficiency. Twenty-eight independent transgenic events were obtained in three transformation experiments using a highly virulent Agrobacterium tumefaciens strain and regeneration through embryogenesis. Molecular analysis indicated that all regenerants were transgenic, with 1-7 transgene loci. Accumulation of transgene-specific siRNA was detected in most of them. None of the transgenic events was immune to SPCSV, but ten of the 20 tested transgenic events exhibited mild or no symptoms following infection, and accumulation of SPCSV was significantly reduced. There are few previous reports of RNA silencing-mediated transgenic resistance to viruses of Closteroviridae in cultivated plants. However, the high levels of resistance to accumulation of SPCSV could not prevent development of synergistic sweet potato virus disease in those transgenic plants also infected with SPFMV.
authors.affiliation: International Potato Center (CIP), Applied Biotechnology Laboratory, Germplasm Enhancement and Crop Improvement Division, PO Box 1558, Lima 12, Peru. j.kreuze@cgiar.org
authors.forename: Jan F
authors.initials: JF
authors.lastname: Kreuze
authors.forename: Ilanit Samolski
authors.initials: IS
authors.lastname: Klein
authors.forename: Milton Untiveros
authors.initials: MU
authors.lastname: Lazaro
authors.forename: Wilmer J Cuellar
authors.initials: WJ
authors.lastname: Chuquiyuri
authors.forename: Gabriela Lajo
authors.initials: GL
authors.lastname: Morgan
authors.forename: Patricia G Cipriani
authors.initials: PG
authors.lastname: Mejía
authors.forename: Marc
authors.initials: M
authors.lastname: Ghislain
authors.forename: Jari P T
authors.initials: JP
authors.lastname: Valkonen
mesh_terms: D015152:Blotting, Northern; D029383:Crinivirus / Q000254:growth & development*; D004269:DNA, Bacterial / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics; D027723:Ipomoea batatas / Q000235:genetics* / Q000821:virology; D010935:Plant Diseases / Q000235:genetics* / Q000821:virology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000821:virology; D017800:Potyvirus / Q000254:growth & development*; D034622:RNA Interference / Q000502:physiology*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics; D014170:Transformation, Genetic
chemical_list: D004269:DNA, Bacterial; C036483:T-DNA; D012324:RNA-Dependent RNA Polymerase