Clusiaceae) Káthia Socorro Mathias Mourão1,2 and Juliana Marzinek1
Total Page：16
File Type：pdf, Size：1020Kb
Acta bot. bras. 23(3): 797-804. 2009 Fruit ontogenesis in Clusia parviflora Humb. & Bonpl. ex Willd. (Clusiaceae) Káthia Socorro Mathias Mourão1,2 and Juliana Marzinek1 Received: May 6, 2008. Accepted: December 1, 2008 RESUMO – (Ontogênese do fruto de Clusia parviflora Humb. & Bonpl. ex Willd. (Clusiaceae)). Aspectos morfo-anatômicos dos frutos e sementes em desenvolvimento de Clusia parviflora são apresentados e discutidos, visando dar continuidade aos estudos com estes órgãos em Clusiaceae. O fruto é cápsula septífraga; o exocarpo suberificado deriva da epiderme externa do ovário. O mesocarpo, originado do mesofilo ovariano, permanece parenquimático. O endocarpo é derivado da epiderme interna do ovário e de três a quatro camadas subepidérmicas, cujas células tangencialmente alongadas tornam-se lignificadas, contribuindo para a deiscência do fruto. Os óvulos são anátropos, bitegumentados, com endotélio, e originam sementes também anátropas, bitegumentadas e exalbuminosas. A exotesta apresenta células de conteúdo fenólico. O exotégmen consta inteiramente de esclereídes com paredes anticlinais onduladas. O restante do tégmen torna-se colapsado. O embrião é levemente curvado e apresenta um eixo hipocótilo-radicular cilíndrico e muito desenvolvido, com dois cotilédones muito pequenos. Parece haver uniformidade em Clusia com relação ao número de camadas no tegumento seminal maduro, mas o número de camadas no tegumento ovulífero pode ser um caráter diagnóstico em nível específico. Palavras-chave: anatomia, Clusia parviflora, Clusiaceae, fruto, semente ABSTRACT – (Fruit ontogenesis in Clusia parviflora Humb. & Bonpl. ex Willd. (Clusiaceae)). Aspects of the morpho-anatomy of developing fruits and seeds of Clusia parviflora are presented and discussed as a continuation of the study of these organs in Clusiaceae. The fruit is a septifrage capsule; the suberized exocarp is derived from the external epidermis of the ovary. The mesocarp originates from the ovarian mesophyll and remains parenchymal in nature. The endocarp is derived from the internal epidermis of the ovary and the endocarp is derived from the inner ovary epidermis as well as from three to four adjacent subepidermal layers, with tangentially elongated cells which become lignified and contribute to fruit dehiscence. The ovules are anatropous, bitegmic, with an endothelium, and give rise to equally anatropous seeds. The exotesta has cells containing phenolic compounds. The exotegmen consists entirely of sclerids with anticlinal and undulating cell walls, while the rest of the tegmen collapses during maturation. The embryo is slightly curved and the hypocotyl-radicle axis is well developed, with two very small cotyledons. There seems to be uniformity in the genus Clusia as regards the final number of layers in the mature seed coat, being evident the continuous lignified exotegmen and the hypocotylar embryo. It should be pointed out that the number of layers in the ovule integument can be used for diagnosis at the species level Key words: anatomy, Clusia parviflora, Clusiaceae, fruit, seed Introduction Materials and methods Clusia parviflora Humb. & Bonpl. ex Willd (Clusiaceae) is a The present study examined the flowers and fruits of Clusia dioecious shrub or tree species occurring in the Atlantic Forest parviflora Humb. & Bonpl. ex Willd. at different development stages, collected in the Núcleo Picinguaba area (São Paulo, Brazil). Reference of Rio de Janeiro, São Paulo, Minas Gerais, and Santa Catarina plant material was prepared and deposited in the HRCB Herbarium states in Brazil (Engler 1888; Engler & Keller 1925; Mariz 1974; under the numbers 9.806, 13.397, 9.470, 9.984. Cronquist 1981; Heywood 1985; Gustafsson et al. 2002). All material used for morphological and anatomical studies was In addition to floral diversity, fruit and seed characteristics fixed in FAA 50 (Johansen 1940) and conserved in 70% ethanol have been used to delimit the subfamilies and tribes of Clusiaceae (Jensen 1962). Anatomical descriptions were based on the analysis of semi-permanent and permanent slides of transversal and (Engler 1888; Brandza 1908; Engler & Keller 1925; Melchior longitudinal sections of developing fruits and seeds. The slides were 1964; Heywood 1985). However, the reduced number of prepared using standard procedures and according to the methodology ontogenetic studies of these organs in this family generates described by Mourão & Beltrati (1995a). The plant material was doubts concerning the relationships and positions of the embedded in historesin according to the specifications of the manufacturer, stained with Toluidine Blue O (O’Brien et al. 1965), species in the subfamilies and tribes. This question was and mounted in Permount. addressed by Mourão & Beltrati (1995a; b; 2000; 2001) who Free-hand sections of fresh material were stained for histochemical described in great detail the morphology, anatomy, and analysis using Sudan III and Sudan IV for lipids; ferric chloride for ontogeny of the fruits and seeds of Platonia insignis phenolic compounds; phloroglucinol and sulfuric acid for lignins (Johansen 1940), and IKI (Jensen 1962) for starch. (Clusioidese-Symphonieae), Vismia guianensis (Hypericoideae- Fruit descriptions were based on Barroso et al. (1999). The Vismeae), and Mammea americana (Kielmeyeroidese- terminology adopted to define the pericarp layers is in agreement Calophylleae), elucidating doubts in the literature about the with Roth (1977), and the nomenclature used for seed coats was based dispersal structures and fruit types of these species. on Corner (1976) as modified by Schmid (1986). The present work examined the morphology and anatomy Results of developing fruits and seeds of C. parviflora (Clusioideae- Clusieae) as a contribution to the study of these organs in Fruit development – After fertilization, the petals and sepals Clusiaceae, with the intent to describe their structure close over and cover the ovary. The petals then fall away comparing with the literature on this subject. while the sepals and sessile stigma remain until fruit 1 Universidade Estadual de Maringá, Departamento de Biologia, Maringá, PR, Brasil 2 Corresponding Author: [email protected] v23n3_20.pmd 797 26/9/2009, 16:31 798 Mourão & Marzinek: Fruit ontogenesis in Clusia parviflora Humb. & Bonpl. ex Willd. (Clusiaceae) maturation (Fig. 1). The fruits of C. parviflora are greenish- longitudinal orientation, and are also observed in the septum yellow spherical capsules approximately 25 mm in diameter. (Fig. 5-6). The seeds and aborted ovules, both covered by a sugar- In the ovary after fertilization (Fig. 7), cell divisions occur rich pulp, are either attached to the central column or to the in all planes. Pericarp structure of immature fruits (Fig. 1) is inner cavity of the fruit valves and become exposed when basically the same as in the ovary both before and after the fruit dehisces (Fig. 2). fertilization (Fig. 3-4, 7). The exocarp, which is derived from The 5-carpellary and 5-locular ovary of C. parviflora is the outer epidermis of the ovary, becomes suberized in the superior and has sessile stigmas. The ovules have axial immature fruit. The mesocarp, which is derived from the ovarian placentation. The outer epidermis of the ovary is uniseriate mesophyll, remains parenchymatic (Fig. 7). The endocarp is and is composed of cubic to slightly elongated cells covered derived from the inner ovary epidermis as well as from three to by a thin cuticle (Fig. 12). Five to six tangentially elongated four adjacent subepidermal layers. The tangentially elongated cells layers define the locule (Fig. 9). The ovarian mesophyll cells of these adjacent layers become lignified during fruit is composed of fundamental parenchyma, where a number development (Fig. 7, 10-11). The dehiscence line occurs along of branched secretory ducts and vascular bundles can be the carpelar suture and consists of small parenchymatic cells, observed. These ramified secretory ducts have a visible in the ovarian mesophyll, that divides into two near Figures 1-4. Clusia parviflora (Sald.) Engler. 1-2. General aspect of the mature fruit before and after dehiscence, respectively, showing the sessile stigma and seeds covered by the aril attached to the central column. 3-4. Medium longitudinal and transversal sections, respectively, showing tissue zonation in the pericarp. ar: aril, cl: columella, ec: endocarp, ep: exocarp, mp: mesocarp, sd: secretory duct, se: seed, sp: sepal, vv: valve (Bar scale = 1.5 cm). v23n3_20.pmd 798 26/9/2009, 16:31 Acta bot. bras. 23(3): 797-804. 2009. 799 the locule (Fig. 5, 7-8, 13); the fruit is a septifrage capsule (Fig. throughout the sides of the seed in development, with the 2). Most of ovules develop into seeds (Fig. 3-4). cells walls of all exotegmen becoming lignified at maturity Seed development – The ovules (Fig. 14-15, 19) are (Fig. 20-22). anatropous and bitegmic; the outer integument is composed The mature seeds are elongated ellipsoids about 5.0 mm of four to five cell layers, while the inner integument is long and 3.0 mm in diameter, and have a brown color. The composed of three to four layers. The inner epidermis of the rounded hilum is completely surrounded by arilar lobes that inner integument has radially elongated cells, which form cover about two thirds of the seed. The dispersal unit is the endothelium. The micropyle channel is formed by the composed of all developed seeds and aborted ovules in endostome and by the exostome, although these openings each locule, covered by