title: Use of the de novo transcriptome analysis of silver-leaf nightshade (Solanum elaeagnifolium) to identify gene expression changes associated with wounding and terpene biosynthesis.
abstract: BACKGROUND
  Solanum elaeagnifolium, an invasive weed of the Solanaceae family, is poorly studied although it poses a significant threat to crops. Here the analysis of the transcriptome of S. elaeagnifolium is presented, as a means to explore the biology of this species and to identify genes related to its adaptation to environmental stress. One of the basic mechanisms by which plants respond to environmental stress is through the synthesis of specific secondary metabolites that protect the plant from herbivores and microorganisms, or serve as signaling molecules. One important such group of secondary metabolites are terpenes.
  
  
  RESULTS
  By next-generation sequencing, the flower/leaf transcriptome of S. elaeagnifolium was sequenced and de novo assembled into 75,618 unigenes. Among the unigenes identified, several corresponded to genes involved in terpene biosynthesis; these included terpene synthases (TPSs) and genes of the mevalonate (MVA) and the methylerythritol phosphate (MEP) pathways. Functional characterization of two of the TPSs showed that one produced the sesquiterpene (E)-caryophyllene and the second produced the monoterpene camphene. Analysis of wounded S. elaeagnifolium leaves has shown significant increase of the concentration of (E)-caryophyllene and geranyl linalool, two terpenes implicated in stress responses. The increased production of (E)-caryophyllene was matched to the induced expression of the corresponding TPS gene. Wounding also led to the increased expression of the putative 1-deoxy-D-xylulose-5-phosphate synthase 2 (DXS2) gene, a key enzyme of the MEP pathway, corroborating the overall increased output of terpene biosynthesis.
  
  
  CONCLUSIONS
  The reported S. elaeagnifolium de novo transcriptome provides a valuable sequence database that could facilitate study of this invasive weed and contribute to our understanding of the highly diverse Solanaceae family. Analysis of genes and pathways involved in the plant's interaction with the environment will help to elucidate the mechanisms that underly the intricate features of this unique Solanum species.
authors.affiliation: Institute of Applied Biosciences, Center for Research and Technology Hellas (CERTH), P.O. Box 60361, Thessaloniki, 57001, Greece. afroditi.tsampalla@gmail.com.
authors.forename: Aphrodite
authors.initials: A
authors.lastname: Tsaballa
authors.affiliation: Institute of Applied Biosciences, Center for Research and Technology Hellas (CERTH), P.O. Box 60361, Thessaloniki, 57001, Greece. nikolchem@hotmail.com.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Nikolaidis
authors.affiliation: Institute of Applied Biosciences, Center for Research and Technology Hellas (CERTH), P.O. Box 60361, Thessaloniki, 57001, Greece. fotaaki@hotmail.co.uk.
authors.forename: Foteini
authors.initials: F
authors.lastname: Trikka
authors.affiliation: Department of Biochemistry, School of Medicine, University of Crete, P.O. Box 2208, Heraklion, 71003, Greece. igneacodruta@yahoo.com.
authors.forename: Codruta
authors.initials: C
authors.lastname: Ignea
authors.affiliation: Department of Biochemistry, School of Medicine, University of Crete, P.O. Box 2208, Heraklion, 71003, Greece. s.kampranis@med.uoc.gr.
authors.forename: Sotirios C
authors.initials: SC
authors.lastname: Kampranis
authors.affiliation: Institute of Applied Biosciences, Center for Research and Technology Hellas (CERTH), P.O. Box 60361, Thessaloniki, 57001, Greece. antoniosmakris@yahoo.gr.
authors.forename: Antonios M
authors.initials: AM
authors.lastname: Makris
authors.affiliation: Institute of Applied Biosciences, Center for Research and Technology Hellas (CERTH), P.O. Box 60361, Thessaloniki, 57001, Greece. argiriou@certh.gr.
authors.forename: Anagnostis
authors.initials: A
authors.lastname: Argiriou
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000081008:Bicyclic Monoterpenes; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D008969:Molecular Sequence Data; D039821:Monoterpenes / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D012834:Silver / Q000378:metabolism; D032322:Solanum / Q000235:genetics* / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics; D013729:Terpenes / Q000378:metabolism*; D059467:Transcriptome / Q000235:genetics*; D014947:Wounds and Injuries / Q000235:genetics*
chemical_list: D000081008:Bicyclic Monoterpenes; D039821:Monoterpenes; D010940:Plant Proteins; D013729:Terpenes; D012834:Silver; D019883:Alkyl and Aryl Transferases; C108877:terpene synthase; C019286:camphene