title: Transcriptome profiling reveals the regulatory mechanism underlying pollination dependent and parthenocarpic fruit set mainly mediated by auxin and gibberellin.
abstract: BACKGROUND
  Fruit set is a key process for crop production in tomato which occurs after successful pollination and fertilization naturally. However, parthenocarpic fruit development can be uncoupled from fertilization triggered by exogenous auxin or gibberellins (GAs). Global transcriptome knowledge during fruit initiation would help to characterize the molecular mechanisms by which these two hormones regulate pollination-dependent and -independent fruit set.
  
  
  RESULTS
  In this work, digital gene expression tag profiling (DGE) technology was applied to compare the transcriptomes from pollinated and 2, 4-D/GA3-treated ovaries. Activation of carbohydrate metabolism, cell division and expansion as well as the down-regulation of MADS-box is a comprehensive regulatory pathway during pollination-dependent and parthenocarpic fruit set. The signaling cascades of auxin and GA are significantly modulated. The feedback regulations of Aux/IAAs and DELLA genes which functioned to fine-tune auxin and GA response respectively play fundamental roles in triggering fruit initiation. In addition, auxin regulates GA synthesis via up-regulation of GA20ox1 and down-regulation of KNOX. Accordingly, the effect of auxin on fruit set is mediated by GA via ARF2 and IAA9 down-regulation, suggesting that both pollination-dependent and parthenocarpic fruit set depend on the crosstalk between auxin and GA.
  
  
  CONCLUSIONS
  This study characterizes the transcriptomic features of ovary development and more importantly unravels the integral roles of auxin and GA on pollination-dependent and parthenocarpic fruit set.
authors.affiliation: Genetic Engineering Research Center, School of Life Sciences, Key Laboratory of Functional Gene and New Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing University, Chongqing 400030, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Tang
authors.affiliation: Genetic Engineering Research Center, School of Life Sciences, Key Laboratory of Functional Gene and New Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing University, Chongqing 400030, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Deng
authors.affiliation: Genetic Engineering Research Center, School of Life Sciences, Key Laboratory of Functional Gene and New Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing University, Chongqing 400030, China.
authors.forename: Guojian
authors.initials: G
authors.lastname: Hu
authors.affiliation: Genetic Engineering Research Center, School of Life Sciences, Key Laboratory of Functional Gene and New Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing University, Chongqing 400030, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Hu
authors.affiliation: Genetic Engineering Research Center, School of Life Sciences, Key Laboratory of Functional Gene and New Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing University, Chongqing 400030, China.
authors.forename: Zhengguo
authors.initials: Z
authors.lastname: Li
mesh_terms: D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D005638:Fruit / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development; D020869:Gene Expression Profiling / Q000379:methods; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D005875:Gibberellins / Q000494:pharmacology*; D007210:Indoleacetic Acids / Q000494:pharmacology*; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics; D054817:Pollination / Q000187:drug effects* / Q000235:genetics*; D059467:Transcriptome / Q000187:drug effects* / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins