Glands of aerial vegetative and floral organs of species of Asclepiadeae from Atlantic rainforest of São Paulo state

Author(s)

Diego Demarco

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2008-11-17

Examining board members

Marilia de Moraes Castro; Jane Elizabeth Kraus; Solange Cristina Mazzoni Viveiros; Luiza Sumiko Kinoshita; Sandra Maria Carmello Guerreiro

• Advisor: Marilia de Moraes Castro

Abstract

The current study aims to carry out a morphological characterization of the secretory structures of aerial vegetative and floral organs of Asclepias curassavica, Fischeria stellata, Gonioanthela axillaris, Matelea denticulata and Oxypetalum banksii subsp. banksii from Atlantic rainforest, analyzing their functions, similarities and dissimilarities in relation to other Asclepiadeae, besides verifying the occurrence of common structural patterns between Apocynacean species. The five species possess interpetiolar foliar and alternisepal calicyne colleters. Asclepias curassavica and Gonioanthela axillaris also present petiolar colleters, Matelea denticulata and Oxypetalum banksii subsp. banksii , laminar ones, and Fischeria stellata, has both. Colleters have palisade epidermis secreting mucilage and lipids that avoid dehydration of buds and fungal proliferation in A. curassavica, F. stellata, M. Denticulata and O. banksii subsp. banksii . Colleters of G. axillaris secrete mucilage exclusively. The bracteolar tip of O. banksii subsp. banksii becomes colleter. Articulated anastomosing laticifers occur in ground and vascular tissues of vegetative and floral organs in those species. The latex of vegetative organs is composed of polysaccharides, including mucilage, proteins, fat acids, phenolic compounds, and alkaloids. Neutral lipids are present only in F. stellata and G. axillaris. The floral latex is constituted of polysaccharides, including mucilage, proteins, lipids, and phenolic compounds. The latex is related to the protection of those plants against herbivory and microorganisms, besides sealing wounds. F. stellata and M. denticulata have glandular trichomes on stem and leaf. Similar trichomes are present on the pedicel and sepals of M. denticulata. They are uniseriate multicellular with an apical secretory cell that produces aminoacids and/or proteins. G. axillaris has oil idioblasts with trilamellar walls registered in pedicel, calyx, and corolla. The flowers of studied species possess staminal wing with epidermis secreting mucilage and lipids related possibly to pollinium retention in the guide rail. The nectariferous-stigmatic chambers present epidermis secreting carbohydrate (including glucose and mucilage) and lipids. Secondary nectaries are found in the corona of G. axillaris, whose epidermis exudes carbohydrates (including glucose and mucilage) and lipids, and in the corona of M. denticulata, where epidermis and parenchyma secrete only carbohydrates (including glucose and mucilage). The floral transmitting system is similar in all the five species. The stigma is composed of non-secretory elongated cells. The solid transmitting tissue is constituted of nonsecretory parenchyma cells that form two isolated bundles below the stigmatic region, except in M. denticulata. In the free styles region, there are canals composed of secretory epidermal cells that are continuous with the placentary-funicular obturator epidermis and secrete mucilage and lipids that fill the stylar canals and ovary locule. The secretory epidermis of style head is responsible for secretion of the translator, formed by corpusculum and caudicles. The corpusculum is composed of mucilage, fat acids, phenolic compounds, and proteins, whereas caudicles are constituted of neutral lipids and mucilage. The tapetal cells secrete lipids and polysaccharides that form a pellicle around the pollinium in all the four species and a hyaline crest in M. denticulata. The pollinia of this species also present pellucid margin. (AU)