title: Identification of genes related to agarwood formation: transcriptome analysis of healthy and wounded tissues of Aquilaria sinensis.
abstract: BACKGROUND
  Agarwood is an expensive resinous heartwood derived from Aquilaria plants that is widely used in traditional medicines, incense and perfume. Only wounded trees can produce agarwood, and the huge demand for the agarwood products has led all Aquilaria spp. being endangered and listed in the Appendix II of the CITES (http://www.cites.org). The major components of agarwood are sesquiterpenes and phenylethyl chromones. Owing to a lack of genomic information, the molecular basis of wound-induced sesquiterpenes biosynthesis and agarwood formation remains unknown.
  
  
  RESULTS
  To identify the primary genes that maybe related to agarwood formation, we sequenced 2 cDNA libraries generated from healthy and wounded A. sinensis (Lour.) Gilg. A total of 89,137 unigenes with an average length of 678.65 bp were obtained, and they were annotated in detail at bioinformatics levels. Of those associated with agarwood formation, 30 putatively encoded enzymes in the sesquiterpene biosynthesis pathway, and a handful of transcription factors and protein kinases were related to wound signal transduction. Three full-length cDNAs of sesquiterpene synthases (ASS1-3) were cloned and expressed in Escherichia coli, and enzyme assays revealed that they are active enzymes, with the major products being δ-guaiene. A methyl jasmonate (MJ) induction experiment revealed that the expression of ASS was significantly induced by MJ, and the production of sesquiterpenes was elevated accordingly. The expression of some transcription factors and protein kinases, especially MYB4, WRKY4, MPKK2 and MAPK2, was also induced by MJ and coordinated with ASS expression, suggesting they maybe positive regulators of ASS.
  
  
  CONCLUSIONS
  This study provides extensive transcriptome information for Aquilaria spp. and valuable clues for elucidating the mechanism of wound-induced agarwood sesquiterpenes biosynthesis and their regulation.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Xu
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Mengxi
authors.initials: M
authors.lastname: Wang
authors.forename: Jianhe
authors.initials: J
authors.lastname: Wei
authors.forename: Hongjiang
authors.initials: H
authors.lastname: Chen
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Gao
authors.forename: Chun
authors.initials: C
authors.lastname: Sui
authors.forename: Hongmei
authors.initials: H
authors.lastname: Luo
authors.forename: Xingli
authors.initials: X
authors.lastname: Zhang
authors.forename: Yun
authors.initials: Y
authors.lastname: Yang
authors.forename: Hui
authors.initials: H
authors.lastname: Meng
authors.forename: Wenlan
authors.initials: W
authors.lastname: Li
mesh_terms: D015723:Gene Library; D017343:Genes, Plant; D058977:Molecular Sequence Annotation; D011494:Protein Kinases / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D017422:Sequence Analysis, DNA; D012717:Sesquiterpenes / Q000378:metabolism; D015398:Signal Transduction; D029645:Thymelaeaceae / Q000235:genetics* / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics; D059467:Transcriptome; D014934:Wood / Q000235:genetics* / Q000254:growth & development
chemical_list: D018749:RNA, Plant; D012717:Sesquiterpenes; D014157:Transcription Factors; D011494:Protein Kinases
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