title: The plant stigma exudate: a biochemically active extracellular environment for pollen germination?
abstract: During sexual reproduction, pollen performance is greatly influenced by the female tissues. The stigma exudate, i.e., the extracellular secretion that covers the stigma outermost surface, has been usually regarded as a reservoir of water, secondary metabolites, cell wall precursors and compounds that serve as energy supply for rapid pollen tube growth. In an attempt to identify the proteins present in the stigma secretome, we performed a large-scale analysis in two species (Lilium longiflorum and Olea europaea) following a proteomic-based approach. The resulting data strongly suggest that the stigma exudate is not a mere storage site but also a biochemically active environment with a markedly catabolic nature. Thus, this secretion may modulate early pollen tube growth and contribute to the senescence of stigma after pollination. In addition, a putative cross-talk between genetic programs that regulate stress/defense and pollination responses in the stigma is also suggested. The stigma exudate might also functionally diverge between species on the basis on their ecology and the biochemical, morphological and anatomical features of their stigmas. Unexpectedly, we identified in both exudates some intracellular proteins, suggesting that a mechanism other than the canonical ER-Golgi exocytic pathway may exist in the stigma and contribute to exudate secretion.
authors.affiliation: Departamento de Bioquímica; Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain.
authors.forename: Juan David
authors.initials: JD
authors.lastname: Rejón
authors.affiliation: Laboratoire de Spectrométrie de Masse Bio-Organique; IPHC-DSA; UdS; CNRS; UMR Strasbourg, France.
authors.forename: François
authors.initials: F
authors.lastname: Delalande
authors.affiliation: Laboratoire de Spectrométrie de Masse Bio-Organique; IPHC-DSA; UdS; CNRS; UMR Strasbourg, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Schaeffer-Reiss
authors.affiliation: Laboratoire de Spectrométrie de Masse Bio-Organique; IPHC-DSA; UdS; CNRS; UMR Strasbourg, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Carapito
authors.affiliation: Departamento de Bioquímica; Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain; Department of Cell Biology; Institute of General and Molecular Biology; Nicolaus Copernicus University; Toruń, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Zienkiewicz
authors.affiliation: Departamento de Bioquímica; Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: de Dios Alché
authors.affiliation: Departamento de Bioquímica; Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Isabel Rodríguez-García
authors.affiliation: Laboratoire de Spectrométrie de Masse Bio-Organique; IPHC-DSA; UdS; CNRS; UMR Strasbourg, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Van Dorsselaer
authors.affiliation: Departamento de Bioquímica; Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain.
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Castro
mesh_terms: D035264:Flowers / Q000502:physiology*; D027762:Lilium / Q000502:physiology*; D031658:Olea / Q000502:physiology*; D053147:Plant Exudates / Q000737:chemistry* / Q000502:physiology; D010940:Plant Proteins / Q000032:analysis*; D011058:Pollen / Q000502:physiology; D040901:Proteomics
chemical_list: D053147:Plant Exudates; D010940:Plant Proteins
keywords: Eastern lily; exudate; olive; proteomics; secretome; stigma