title: Transcriptional profile of sweet orange in response to chitosan and salicylic acid.
abstract: BACKGROUND
  Resistance inducers have been used in annual crops as an alternative for disease control. Wood perennial fruit trees, such as those of the citrus species, are candidates for treatment with resistance inducers, such as salicylic acid (SA) and chitosan (CHI). However, the involved mechanisms in resistance induced by elicitors in citrus are currently few known.
  
  
  RESULTS
  In the present manuscript, we report information regarding the transcriptional changes observed in sweet orange in response to exogenous applications of SA and CHI using RNA-seq technology. More genes were induced by SA treatment than by CHI treatment. In total, 1,425 differentially expressed genes (DEGs) were identified following treatment with SA, including the important genes WRKY50, PR2, and PR9, which are known to participate in the salicylic acid signaling pathway, and genes involved in ethylene/Jasmonic acid biosynthesis (ACS12, AP2 domain-containing transcription factor, and OPR3). In addition, SA treatment promoted the induction of a subset of genes involved in several metabolic processes, such as redox states and secondary metabolism, which are associated with biotic stress. For CHI treatment, there were 640 DEGs, many of them involved in secondary metabolism. For both SA and CHI treatments, the auxin pathway genes were repressed, but SA treatment promoted induction in the ethylene and jasmonate acid pathway genes, in addition to repressing the abscisic acid pathway genes. Chitosan treatment altered some hormone metabolism pathways. The DEGs were validated by quantitative Real-Time PCR (qRT-PCR), and the results were consistent with the RNA-seq data, with a high correlation between the two analyses.
  
  
  CONCLUSIONS
  We expanded the available information regarding induced defense by elicitors in a species of Citrus that is susceptible to various diseases and identified the molecular mechanisms by which this defense might be mediated.
authors.affiliation: Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, IAC, Cordeirópolis, São Paulo, Brasil. danilasoc@yahoo.com.br.|Universidade Federal da Bahia, UFBA, Vitória da Conquista, Bahia, Brasil. danilasoc@yahoo.com.br.
authors.forename: Danila Souza Oliveira
authors.initials: DS
authors.lastname: Coqueiro
authors.affiliation: Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, IAC, Cordeirópolis, São Paulo, Brasil. alessandra@centrodecitricultura.br.
authors.forename: Alessandra Alves
authors.initials: AA
authors.lastname: de Souza
authors.affiliation: Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, IAC, Cordeirópolis, São Paulo, Brasil. takita@centrodecitricultura.br.
authors.forename: Marco Aurélio
authors.initials: MA
authors.lastname: Takita
authors.affiliation: Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, IAC, Cordeirópolis, São Paulo, Brasil. carolina@centrodecitricultura.br.
authors.forename: Carolina Munari
authors.initials: CM
authors.lastname: Rodrigues
authors.affiliation: Universidade Federal de São Carlos, São Carlos, São Paulo, Brasil. luciano.kishi@gmail.com.
authors.forename: Luciano Takeshi
authors.initials: LT
authors.lastname: Kishi
authors.affiliation: Laboratório de Biotecnologia, Centro de Citricultura Sylvio Moreira, IAC, Cordeirópolis, São Paulo, Brasil. marcos@centrodecitricultura.br.
authors.forename: Marcos Antonio
authors.initials: MA
authors.lastname: Machado
mesh_terms: D048271:Chitosan / Q000494:pharmacology*; D032084:Citrus sinensis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects*; D020869:Gene Expression Profiling; D017343:Genes, Plant; D010084:Oxidation-Reduction; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology*; D017423:Sequence Analysis, RNA; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D010937:Plant Growth Regulators; D014157:Transcription Factors; D012313:RNA; D048271:Chitosan; D020156:Salicylic Acid