title: Transcriptomic events involved in melon mature-fruit abscission comprise the sequential induction of cell-wall degrading genes coupled to a stimulation of endo and exocytosis.
abstract: BACKGROUND
  Mature-fruit abscission (MFA) in fleshy-fruit is a genetically controlled process with mechanisms that, contrary to immature-fruit abscission, has not been fully characterized. Here, we use pyrosequencing to characterize the transcriptomes of melon abscission zone (AZ) at three stages during AZ-cell separation in order to understand MFA control at an early stage of AZ-activation.
  
  
  RESULTS
  The results show that by early induction of MFA, the melon AZ exhibits major gene induction, while by late induction of MFA, melon AZ shows major gene repression. Although some genes displayed similar regulation in both early and late induction of abscission, such as EXT1-EXT4, EGase1, IAA2, ERF1, AP2D15, FLC, MADS2, ERAF17, SAP5 and SCL13 genes, the majority had different expression patterns. This implies that time-specific events occur during MFA, and emphasizes the value of characterizing multiple time-specific abscission transcriptomes. Analysis of gene-expression from these AZs reveal that a sequential induction of cell-wall-degrading genes is associated with the upregulation of genes involved in endo and exocytosis, and a shift in plant-hormone metabolism and signaling genes during MFA. This is accompanied by transcriptional activity of small-GTPases and synthaxins together with tubulins, dynamins, V-type ATPases and kinesin-like proteins potentially involved in MFA signaling. Early events are potentially controlled by down-regulation of MADS-box, AP2/ERF and Aux/IAA transcription-factors, and up-regulation of homeobox, zinc finger, bZIP, and WRKY transcription-factors, while late events may be controlled by up-regulation of MYB transcription-factors.
  
  
  CONCLUSIONS
  Overall, the data provide a comprehensive view on MFA in fleshy-fruit, identifying candidate genes and pathways associated with early induction of MFA. Our comprehensive gene-expression profile will be very useful for elucidating gene regulatory networks of the MFA in fleshy-fruit.
authors.affiliation: Department of Plant Physiology, University of Extremadura, Avda de Elvas s/n, Badajoz, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Corbacho
authors.forename: Félix
authors.initials: F
authors.lastname: Romojaro
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Pech
authors.forename: Alain
authors.initials: A
authors.lastname: Latché
authors.forename: Maria C
authors.initials: MC
authors.lastname: Gomez-Jimenez
mesh_terms: D002473:Cell Wall / Q000235:genetics / Q000378:metabolism; D019295:Computational Biology; D019662:Cucurbitaceae / Q000235:genetics / Q000502:physiology*; D004705:Endocytosis / Q000235:genetics / Q000502:physiology; D005089:Exocytosis / Q000235:genetics / Q000502:physiology; D005638:Fruit / Q000378:metabolism* / Q000502:physiology*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology*; D017343:Genes, Plant / Q000235:genetics*; D058977:Molecular Sequence Annotation; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics*
chemical_list: D014157:Transcription Factors