Anatomia foliar aplicada à taxonomia em Rubiaceae Juss

• Autor(a) principal: Mattos, Karina Lucas Barbosa Lopes
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/370
• topic: Rubiaceae; Taxonomia; Reserva florestal Mata do Paraíso; Coléter; Rubiaceae; Taxonomy; Forest reserve Mata do Paraíso; Colleter; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::MORFOLOGIA VEGETAL::ANATOMIA VEGETAL

Rubiaceae comprise about 660 genera and 11,150 species, within the subfamilies Cinchonoideae and Rubioideae. In Brazil, it is represented by 18 tribes, 101 genera and approximately 1000 species, distributed among different vegetation formations, with a large occurrence in the Atlantic Forest. Because of the high species richness of Rubiaceae in Mata do Paraíso Forest Reserve (RFMP), the problems related to taxonomic delimitation of genera, tribes and subfamilies and the importance of anatomy as a tool for taxonomy, this study aimed to identify anatomical leaf characters to aid in taxonomy and phylogeny of Rubiaceae. Anatomical and micromorphological characteristics of leaf colleters were also recorded from a number of representatives. Leaves were examined, including the middle region of fully expanded leaf blades (midrib and margin) and petiole (middle third) of 30 Rubiaceae species, distributed in 7 tribes and 12 genera collected in the RFMP. Studies on morphology, anatomy and histochemistry of colleters were also carried out in 10 species belonging to four genera of Rubiaceae. The samples were processed by usual plant anatomy techniques and anatomical data was analyzed by multivariate numerical techniques. Taxonomically important anatomical characters considered were: presence of biseriate epidermis, papillae, presence of unicellular and multicellular trichomes, paracytic and parallelocytic stomata, presence of colleters, domatia and variations in the pattern of leaf areolation and conformation of the petiole vascular system. Several useful characteristics had diagnostic value in the differentiation and recognition of the species in RFMP. Phenetic analysis confirmed the formation of small groups at the tribe level (Spermacoceae, Cinchoneae, Cossareae, Coccocypseleae, Psychotrieae) and genus (Borreria, Diodella, Coccocypselum). The principal component analysis grouped the species into three supertribes: Psychotriidinae, Rubiidinae and Cinchonidinae. Colleters occur on the adaxial surface of stipules, on leaf primordia of Palicourea maracgravii and also at stipule apices of Chiococca alba. Three types of colleters were indentified: standard, bifurcated standard and reduced standard. The general structure of colleters consists of a central axis and a parenchymatous multicellular palisade secretory epidermis, which are cuboidal or elongated to the full extent of the colleter. The cuticle and epidermal cells have thin walls, conspicuous nuclei displaced to the equatorial or basal region and abundant cytoplasm. Intercellular spaces often occur between the epidermal cells of C. alba, Coussarea triflora, C. verticillata and Psychotria sessilis. Cristals idioblasts containing raphides occur in the parenchyma of the central axis of colleters in all Rubioideae species. Crystalline sand is present only in C. alba (Cinchonoideae). Vascular traces were present in the parenchymatous central axis of P. longepedunculata and P. maracgravii. The positive reaction to histochemical tests showed that the secretion consists of mucilaginous and protein substances in the samples analyzed. The position, the typological variation, vascularity, the presence and type of calcium oxalate crystals are important characteristics for the study of taxonomy and phylogeny of Rubiaceae. The anatomical studies in Rubiaceae species here performed reinforce the importance of anatomical characters as an additional tool to support taxonomic and phylogenetic studies in the family, as well as extend the anatomic knowledge at generic and specific levels.