title: Analysis of the transcriptional responses in inflorescence buds of Jatropha curcas exposed to cytokinin treatment.
abstract: BACKGROUND
  Jatropha curcas L. is a potential biofuel plant. Application of exogenous cytokinin (6-benzyladenine, BA) on its inflorescence buds can significantly increase the number of female flowers, thereby improving seed yield. To investigate which genes and signal pathways are involved in the response to cytokinin in J. curcas inflorescence buds, we monitored transcriptional activity in inflorescences at 0, 3, 12, 24, and 48 h after BA treatment using a microarray.
  
  
  RESULTS
  We detected 5,555 differentially expressed transcripts over the course of the experiment, which could be grouped into 12 distinct temporal expression patterns. We also identified 31 and 131 transcripts in J. curcas whose homologs in model plants function in flowering and phytohormonal signaling pathways, respectively. According to the transcriptional analysis of genes involved in flower development, we hypothesized that BA treatment delays floral organ formation by inhibiting the transcription of the A, B and E classes of floral organ-identity genes, which would allow more time to generate more floral primordia in inflorescence meristems, thereby enhancing inflorescence branching and significantly increasing flower number per inflorescence. BA treatment might also play an important role in maintaining the flowering signals by activating the transcription of GIGANTEA (GI) and inactivating the transcription of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) and TERMINAL FLOWER 1b (TFL1b). In addition, exogenous cytokinin treatment could regulate the expression of genes involved in the metabolism and signaling of other phytohormones, indicating that cytokinin and other phytohormones jointly regulate flower development in J. curcas inflorescence buds.
  
  
  CONCLUSIONS
  Our study provides a framework to better understand the molecular mechanisms underlying changes in flowering traits in response to cytokinin treatment in J. curcas inflorescence buds. The results provide valuable information related to the mechanisms of cross-talk among multiple phytohormone signaling pathways in woody plants.
authors.forename: Mao-Sheng
authors.initials: MS
authors.lastname: Chen
authors.forename: Bang-Zhen
authors.initials: BZ
authors.lastname: Pan
authors.forename: Gui-Juan
authors.initials: GJ
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Ni
authors.forename: Longjian
authors.initials: L
authors.lastname: Niu
authors.forename: Zeng-Fu
authors.initials: ZF
authors.lastname: Xu
mesh_terms: D001593:Benzyl Compounds; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D056626:Inflorescence / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D031286:Jatropha / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D007701:Kinetin / Q000235:genetics* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010937:Plant Growth Regulators / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011687:Purines
chemical_list: D001593:Benzyl Compounds; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011687:Purines; C480551:benzylaminopurine; D007701:Kinetin