title: Carica papaya microRNAs are responsive to Papaya meleira virus infection.
abstract: MicroRNAs are implicated in the response to biotic stresses. Papaya meleira virus (PMeV) is the causal agent of sticky disease, a commercially important pathology in papaya for which there are currently no resistant varieties. PMeV has a number of unusual features, such as residence in the laticifers of infected plants, and the response of the papaya to PMeV infection is not well understood. The protein levels of 20S proteasome subunits increase during PMeV infection, suggesting that proteolysis could be an important aspect of the plant defense response mechanism. To date, 10,598 plant microRNAs have been identified in the Plant miRNAs Database, but only two, miR162 and miR403, are from papaya. In this study, known plant microRNA sequences were used to search for potential microRNAs in the papaya genome. A total of 462 microRNAs, representing 72 microRNA families, were identified. The expression of 11 microRNAs, whose targets are involved in 20S and 26S proteasomal degradation and in other stress response pathways, was compared by real-time PCR in healthy and infected papaya leaf tissue. We found that the expression of miRNAs involved in proteasomal degradation increased in response to very low levels of PMeV titre and decreased as the viral titre increased. In contrast, miRNAs implicated in the plant response to biotic stress decreased their expression at very low level of PMeV and increased at high PMeV levels. Corroborating with this results, analysed target genes for this miRNAs had their expression modulated in a dependent manner. This study represents a comprehensive identification of conserved miRNAs inpapaya. The data presented here might help to complement the available molecular and genomic tools for the study of papaya. The differential expression of some miRNAs and identifying their target genes will be helpful for understanding the regulation and interaction of PMeV and papaya.
authors: Núcleo de Biotecnologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil.
authors: Paolla M V
authors: PM
authors: Abreu
authors: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors: Clicia G
authors: CG
authors: Gaspar
authors: Núcleo de Biotecnologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil.
authors: David S
authors: DS
authors: Buss
authors: Núcleo de Biotecnologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil; Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural, Vitória, Espírito Santo, Brazil.
authors: José A
authors: JA
authors: Ventura
authors: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors: Paulo C G
authors: PC
authors: Ferreira
authors: Núcleo de Biotecnologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil.
authors: Patricia M B
authors: PM
authors: Fernandes
mesh_terms: D001483:Base Sequence; D029441:Carica / Q000235:genetics* / Q000378:metabolism; D030541:Databases, Genetic; D020224:Expressed Sequence Tags; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D035683:MicroRNAs / Q000145:classification / Q000378:metabolism*; D010802:Phylogeny; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010942:Plant Viruses / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D016415:Sequence Alignment; D019562:Viral Load
chemical_list: D035683:MicroRNAs; D017382:Reactive Oxygen Species; D046988:Proteasome Endopeptidase Complex