title: Comparative transcriptional profiling analysis of the two daughter cells from tobacco zygote reveals the transcriptome differences in the apical and basal cells.
abstract: BACKGROUND
  In angiosperm, after the first asymmetric zygotic cell division, the apical and basal daughter cells follow distinct development pathways. Global transcriptome analysis of these two cells is essential in understanding their developmental differences. However, because of the difficulty to isolate the in vivo apical and basal cells of two-celled proembryo from ovule and ovary in higher plants, the transcriptome analysis of them hasn't been reported.
  
  
  RESULTS
  In this study, we developed a procedure for isolating the in vivo apical and basal cells of the two-celled proembryo from tobacco (Nicotiana tabacum), and then performed a comparative transcriptome analysis of the two cells by suppression subtractive hybridization (SSH) combined with macroarray screening. After sequencing, we identified 797 differentially expressed ESTs corresponding to 299 unigenes. Library sequence analysis successfully identified tobacco homologies of genes involved in embryogenesis and seed development. By quantitative real-time PCR, we validated the differential expression of 40 genes, with 6 transcripts of them specifically expressed in the apical or basal cell. Expression analysis also revealed some transcripts displayed cell specific activation in one of the daughter cells after zygote division. These differential expressions were further validated by in situ hybridization (ISH). Tissue expression pattern analysis also revealed some potential roles of these candidate genes in development.
  
  
  CONCLUSIONS
  The results show that some differential or specific transcripts in the apical and basal cells of two-celled proembryo were successfully isolated, and the identification of these transcripts reveals that these two daughter cells possess distinct transcriptional profiles after zygote division. Further functional work on these differentially or specifically expressed genes will promote the elucidation of molecular mechanism controlling early embryogenesis.
authors.affiliation: Key Laboratory of the Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
authors.forename: Tian-Xiang
authors.initials: TX
authors.lastname: Hu
authors.forename: Miao
authors.initials: M
authors.lastname: Yu
authors.forename: Jie
authors.initials: J
authors.lastname: Zhao
mesh_terms: D002455:Cell Division; D002477:Cells / Q000378:metabolism*; D019295:Computational Biology; D018076:DNA, Complementary / Q000096:biosynthesis; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D015203:Reproducibility of Results; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*; D015053:Zygote / Q000166:cytology*
chemical_list: D018076:DNA, Complementary