title: Ontogenesis secretion and senescence of Tocoyena bullata (Vell.) Mart. (Rubiacaeae) colleters.
abstract: Colleters are secretory structure present on many families including Rubiaceae. Particular characteristics have been described about colleters secretory cells, however senescence process are still under debate. Tocoyena bullata (Vell.) Mart. (Rubiaceae) shoot apex were collected at Jardim Botânico do Rio de Janeiro, RJ/Brazil. Stipules were separated and fragments were fixed in 2.5% glutaraldehyde and 4.0% formaldehyde in 0.05 m sodium cacodylate buffer, pH 7.2, post fixed in 1.0% osmium tetroxide in the same buffer, dehydrated in acetone, critical-point-drying, sputtered coated and observed. For light microscopy fragments were fixed and dehydrated, infiltrated with historesin and stained with 1% toluidine blue. For transmission electron microscopy, the samples were infiltrated with Epoxi resin. Colleters are present on stipule adaxial surface. On the beginning of development, these structures are recognized as small projections. Later on, colleters differentiated and secrete by cuticle rupture. The colleters senescence occurs in a concomitant and indissoluble way of programmed cell death. Ultrastructural analyses during the process strongly suggest the senescence is based on a non-autolitic programmed cell death. T. bullata colleters, present at stipule abaxial surface are cylindrical secretory structures. Colleters secretory cells originated as stipule projections; differentiate; secrete and senesce by programmed cell death. The secretion and the cell dead occurs in a concomitantly and indissoluble way.
authors.affiliation: Departamento de Física, Central Analítica UFC, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil.
authors.forename: E C
authors.initials: EC
authors.lastname: Miguel
authors.affiliation: Departamento de Física, Laboratório de Universidade Federal do Ceará, Fortaleza, Ceará, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Da Cunha
authors.affiliation: Centro de Biociências e Biotecnologia, Laboratório de Biologia Celular e Tecidual, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Rio de Janeiro, Brazil.
authors.forename: T B A R
authors.initials: TB
authors.lastname: Miguel
authors.affiliation: Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, Diretoria de Pesquisas, Laborato rio de Botâanica Estrutural, Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: C F
authors.initials: CF
authors.lastname: Barros
mesh_terms: D017209:Apoptosis; D001938:Brazil; D003890:Desiccation; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D018520:Plant Shoots / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure; D019666:Rubiaceae / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D013045:Species Specificity
keywords: Electron microscopy; Rubiaceae; Tocoyena; plant anatomy; plant programmed cell death; secretory structure