title: Unveiling the osmophores of Philodendron adamantinum (Araceae) as a means to understanding interactions with pollinators.
abstract: Araceae species pollinated by nocturnal Cyclocephalini beetles attract their pollinators by inflorescence scents. In Philodendron , despite the intense odour, the osmophores exhibit no definite morphological identity, making them difficult to locate. This may explain why structural studies of the scent-releasing tissue are not available so far.
  
  
  
  Several approaches were employed for locating and understanding the osmophores of Philodendron adamantinum . A sensory test allowed other analyses to be restricted to fertile and sterile stamens as odour production sites. Stamens were studied under light and electron microscopy. Dynamic headspace and gas chromatography-mass spectrometry were used to collect and analyse scents from different zones of the inflorescence.
  
  
  
  The epidermal cells of the distal portion of fertile stamens and staminodes are papillose and, similar to the parenchyma cells of this region, have dense cytoplasm and large nuclei. In these cells, the composition of organelles is compatible with secretory activity, especially the great number of mitochondria and plastids. In this portion, lipid droplets that are consumed concomitantly with the release of odour were observed. Quantitative scent analyses revealed that the scent, with a predominance of dihydro-β-ionone, is mainly emitted by the fertile and sterile staminate zones of the spadix. An amorphous substance in the stomata pores indicates that the components are secreted and volatilized outside of the osmophore under thermogenic heat.
  
  
  
  Despite the difficulty in locating osmophores in the absence of morphological identity and inefficiency of neutral red staining, the osmophores of P. adamantinum have some features expected for these structures. The results indicate a functional link between thermogenesis and volatilization of osmophore secretions to produce olfactory signals for attracting specialized beetle pollinators. These first experimental data about the precise location of osmophores in Philodendron will stimulate studies in related species that will allow future comparison and the establishment of patterns of functional morphology.
authors.affiliation: Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil and.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Gonçalves-Souza
authors.affiliation: Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil and.
authors.forename: Clemens
authors.initials: C
authors.lastname: Schlindwein
authors.affiliation: Department of Ecology and Evolution, Plant Ecology, University of Salzburg, 5020 Salzburg, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Dötterl
authors.affiliation: Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil and.
authors.forename: Elder Antônio Sousa
authors.initials: EA
authors.lastname: Paiva
mesh_terms: D000818:Animals; D001517:Coleoptera; D035264:Flowers / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D008401:Gas Chromatography-Mass Spectrometry; D008854:Microscopy, Electron; D031062:Philodendron / Q000033:anatomy & histology* / Q000502:physiology; D054817:Pollination / Q000502:physiology; D055549:Volatile Organic Compounds / Q000032:analysis / Q000378:metabolism
chemical_list: D055549:Volatile Organic Compounds
keywords: Araceae; Philodendron; cellular ultrastructure; insect–plant interaction; osmophores; pollination