title: Transcriptome analysis of the differentially expressed genes in the male and female shrub willows (Salix suchowensis).
abstract: BACKGROUND
  The dioecious system is relatively rare in plants. Shrub willow is an annual flowering dioecious woody plant, and possesses many characteristics that lend it as a great model for tracking the missing pieces of sex determination evolution. To gain a global view of the genes differentially expressed in the male and female shrub willows and to develop a database for further studies, we performed a large-scale transcriptome sequencing of flower buds which were separately collected from two types of sexes.
  
  
  RESULTS
  Totally, 1,201,931 high quality reads were obtained, with an average length of 389 bp and a total length of 467.96 Mb. The ESTs were assembled into 29,048 contigs, and 132,709 singletons. These unigenes were further functionally annotated by comparing their sequences to different proteins and functional domain databases and assigned with Gene Ontology (GO) terms. A biochemical pathway database containing 291 predicted pathways was also created based on the annotations of the unigenes. Digital expression analysis identified 806 differentially expressed genes between the male and female flower buds. And 33 of them located on the incipient sex chromosome of Salicaceae, among which, 12 genes might involve in plant sex determination empirically. These genes were worthy of special notification in future studies.
  
  
  CONCLUSIONS
  In this study, a large number of EST sequences were generated from the flower buds of a male and a female shrub willow. We also reported the differentially expressed genes between the two sex-type flowers. This work provides valuable information and sequence resources for uncovering the sex determining genes and for future functional genomics analysis of Salicaceae spp.
authors.affiliation: Key Lab of Forest Genetics and Biotechnology, Nanjing Forestry University, Nanjing, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Liu
authors.forename: Tongming
authors.initials: T
authors.lastname: Yin
authors.forename: Ning
authors.initials: N
authors.lastname: Ye
authors.forename: Yingnan
authors.initials: Y
authors.lastname: Chen
authors.forename: Tingting
authors.initials: T
authors.lastname: Yin
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.forename: Danial
authors.initials: D
authors.lastname: Hassani
mesh_terms: D032461:Chromosomes, Plant; D030541:Databases, Genetic; D020224:Expressed Sequence Tags; D035264:Flowers / Q000235:genetics*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D018895:Microsatellite Repeats; D058977:Molecular Sequence Annotation; D032108:Salix / Q000235:genetics*; D017422:Sequence Analysis, DNA; D059467:Transcriptome
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