title: Gene expression profile analysis of tobacco leaf trichomes.
abstract: BACKGROUND
  Leaf trichomes of Nicotiana tabacum are distinguished by their large size, high density, and superior secretion ability. They contribute to plant defense response against biotic and abiotic stress, and also influence leaf aroma and smoke flavor. However, there is limited genomic information about trichomes of this non-model plant species.
  
  
  RESULTS
  We have characterized Nicotiana tabacum leaf trichome gene expression using two approaches. In the first, a trichome cDNA library was randomly sequenced, and 2831 unique genes were obtained. The most highly abundant transcript was ribulose bisphosphate carboxylase (RuBisCO). Among the related sequences, most encoded enzymes involved in primary metabolism. Secondary metabolism related genes, such as isoprenoid and flavonoid biosynthesis-related, were also identified. In the second approach, a cDNA microarray prepared from these 2831 clones was used to compare gene expression levels in trichome and leaf. There were 438 differentially expressed genes between trichome and leaves-minus-trichomes. Of these, 207 highly expressed genes in tobacco trichomes were enriched in second metabolic processes, defense responses, and the metabolism regulation categories. The expression of selected unigenes was confirmed by semi-quantitative RT-PCR analysis, some of which were specifically expressed in trichomes.
  
  
  CONCLUSIONS
  The expression feature of leaf trichomes in Nicotiana tabacum indicates their metabolic activity and potential importance in stress resistance. Sequences predominantly expressed in trichomes will facilitate gene-mining and metabolism control of plant trichome.
authors.affiliation: Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan, Agricultural University, Zhengzhou, 450002, PR China. cuihonger_13@163.com
authors.forename: Hong
authors.initials: H
authors.lastname: Cui
authors.forename: Song-Tao
authors.initials: ST
authors.lastname: Zhang
authors.forename: Hui-Juan
authors.initials: HJ
authors.lastname: Yang
authors.forename: Hao
authors.initials: H
authors.lastname: Ji
authors.forename: Xiu-Jie
authors.initials: XJ
authors.lastname: Wang
mesh_terms: D001483:Base Sequence; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D017343:Genes, Plant; D008855:Microscopy, Electron, Scanning; D020411:Oligonucleotide Array Sequence Analysis; D018515:Plant Leaves / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics; D016415:Sequence Alignment / Q000379:methods; D013729:Terpenes / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D015854:Up-Regulation
chemical_list: D010940:Plant Proteins; D013729:Terpenes; D012273:Ribulose-Bisphosphate Carboxylase