title: Function and diversity of P0 proteins among cotton leafroll dwarf virus isolates.
abstract: BACKGROUND
  The RNA silencing pathway is an important anti-viral defense mechanism in plants. As a counter defense, some members of the viral family Luteoviridae are able to evade host immunity by encoding the P0 RNA silencing suppressor protein. Here we explored the functional diversity of P0 proteins among eight cotton leafroll dwarf virus (CLRDV) isolates, a virus associated with a worldwide cotton disease known as cotton blue disease (CBD).
  
  
  METHODS
  CLRDV-infected cotton plants of different varieties were collected from five growing fields in Brazil and their P0 sequences compared to three previously obtained isolates. P0's silencing suppression activities were scored based on transient expression experiments in Nicotiana benthamiana leaves.
  
  
  RESULTS
  High sequence diversity was observed among CLRDV P0 proteins, indicating that some isolates found in cotton varieties formerly resistant to CLRDV should be regarded as new genotypes within the species. All tested proteins were able to suppress local and systemic silencing, but with significantly variable degrees. All P0 proteins were able to mediate the decay of ARGONAUTE proteins, a key component of the RNA silencing machinery.
  
  
  CONCLUSIONS
  The sequence diversity observed in CLRDV P0s is also reflected in their silencing suppression capabilities. However, the strength of local and systemic silencing suppression was not correlated for some proteins.
authors.affiliation: Department of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil. renan_cascardo@yahoo.com.br.
authors.forename: Renan S
authors.initials: RS
authors.lastname: Cascardo
authors.affiliation: Department of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil. ighorlag@gmail.com.
authors.forename: Ighor L G
authors.initials: IL
authors.lastname: Arantes
authors.affiliation: Department of Virology, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil. tatianedafranca@usp.br.|Present address: Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, Lorena, São Paulo, Brazil. tatianedafranca@usp.br.
authors.forename: Tatiane F
authors.initials: TF
authors.lastname: Silva
authors.affiliation: Department of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil. sachetto@biologia.ufrj.br.
authors.forename: Gilberto
authors.initials: G
authors.lastname: Sachetto-Martins
authors.affiliation: Department of Virology, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil. maite@micro.ufrj.br.
authors.forename: Maité F S
authors.initials: MF
authors.lastname: Vaslin
authors.affiliation: Department of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil. regislcorrea@ufrj.br.
authors.forename: Régis L
authors.initials: RL
authors.lastname: Corrêa
mesh_terms: D001938:Brazil; D015870:Gene Expression; D020868:Gene Silencing; D017930:Genes, Reporter; D014644:Genetic Variation; D005843:Geography; D003368:Gossypium / Q000821:virology*; D052679:Luteoviridae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D010935:Plant Diseases / Q000821:virology*; D030821:Plants, Genetically Modified; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D014764:Viral Proteins