Desenvolvimento e anatomia dos órgãos reprodutivos de Anthurium Schott (Araceae, Alismatales) e suas implicações na taxonomia
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Data
2017-05-10
Autores
Poli, Letícia Peres [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Anthurium é o maior gênero de Araceae e compreende 950 espécies endêmicas dos neotrópicos. No Brasil, o gênero está representado por 133 espécies circunscritas, principalmente, nas seções Anthurium sect. Urospadix e A. sect. Pachyneurium, além de A. sect. Dactylophyllium e A. sect. Tetraspermium. O estudo ontogenético, micromorfológico, anatômico e de biologia floral em espécies de Anthurium pode auxiliar com caracteres significativos para sua taxonomia e sistemática que são baseadas, predominantemente, em características morfológicas foliares. Na presente tese foram analisadas 20 espécies de quatro seções de Anthurium, sob estereomicroscópio e microscopias de luz, eletrônica de varredura e confocal de varredura a laser. No Capítulo 1, nós avaliamos o uso dos caracteres ontogenéticos, micromorfológicos e anatômicos florais, principalmente do perigônio e do androceu, nas seções/clados selecionados de Anthurium. Destacam-se a caracterização anatômica inédita dos osmóforos, além de variação no formato da parede periclinal externa e no conteúdo apresentado pelas células epidérmicas das tépalas e a variação na sobreposição das tépalas externas no botão floral e na exposição dos estames. Através do estudo de vascularização floral (Capítulo 2), nós verificamos que a vascularização do perigônio e do androceu mostraram-se uniformes entre as seções estudadas. No entanto, dois padrões de vascularização do gineceu foram encontrados: carpelos vascularizados apenas por feixes sinlaterais (Padrão A), característica compartilhada pela maioria das espécies estudadas, e carpelos vascularizados por feixes dorsais e sinlaterais (Padrão B), padrão inédito para o gênero e encontrado em A. affine (A. sect. Pachyneurium), A. obtusum e A. scandens (A. sect. Tetraspermium). No capítulo 3, nosso objetivo principal foi investigar a separação das fases estaminada e pistilada nas flores (dicogamia intrafloral) e entre flores do mesmo indivíduo (dicogamia interfloral). Nossos dados mostram que a dicogamia intrafloral completa ocorre em todas as espécies estudadas, porém, em A. scandens (A. sect. Tetraspermium) e em A. solitarium (A. sect. Pachyneurium series Pachyneurium), registramos, pela primeira vez, a sincronia de anteses feminina e masculina, sugerindo a possível ocorrência de geitonogamia. O conjunto de dados aqui apresentados, juntamente com aqueles da literatura, revelam que a maioria das características ontogenéticas, micromorfológicas, anatômicas florais é uniforme para as quatro seções estudadas do gênero. Parte das variações aqui encontradas, quando analisadas na filogenia atual de Anthurium, indica características diagnósticas para A. sect. Urospadix (Capítulo 1) e demais ramos evolutivos (Capítulo 2), além disso, aspectos da biologia floral (Capítulo 3), como a sincronia das fases estaminada e pistilada, a liberação de odor pelas tépalas e a direção da antese masculina no espádice, ampliam o conhecimento sobre a biologia floral em Anthurium e contribuem com dados para estudos futuros, principalmente, sobre biologia da polinização nas espécies brasileiras.
Anthurium is the largest genus of Araceae with 950 endemic Neotropical species. In Brazil, the genus comprises 133 species circumscribed mainly within Anthurium sect. Urospadix and A. sect. Pachyneurium, as well as within A. sect. Dactylophyllium and A. sect. Tetraspermium. The ontogenetic, micromorphological, anatomical and floral biology studies of Anthurium can help with significant characters for its taxonomy and systematic, which are based predominantly on foliar morphological features. In this Thesis we analyzed 20 species belonging to four sections of Anthurium, using stereomicroscope, and light, scanning confocal laser and scanning electron microscopies. In Chapter 1, we evaluated the use of ontogenetic, micromorphological and anatomical floral characters, mainly of the perigone and androecium, in the selected sections/clades of Anthurium. We highlight the anatomical characterization of the osmophores, as well as the variation in the shape of outer periclinal wall and in the content presented by the epidermal cells; variation in the overlapping of the outer tepals in the floral bud and in the exposure of the stamens were also pointed out. In Chapter 2, we verified that the vasculature of the perigone and the androecium were uniform amongst the sections studied. However, two patterns of gynoecial vasculature were described: carpels vascularized by synlateral bundles alone (Pattern A), shared by the majority of species studied, and carpels vascularized by both dorsal and synlateral bundles (Pattern B), which occurs in A. affine (A. sect. Pachyneurium), A. obtusum and A. scandens (A. sect. Tetraspermium). Pattern B is a new feature for the genus. In Chapter 3, our main objective was to investigate the separation of both staminate and pistillate phases within the flowers (intrafloral dichogamy) and among flowers of the same plant (interfloral dichogamy). Our data show that complete intrafloral dichogamy occurs in all species studied, except A. scandens (A. sect. Tetraspermium) and A. solitarium (A. sect. Pachyneurium series Pachyneurium), in which we observed, for the first time, the synchrony of both staminate and pistillate phases, suggesting the possible occurrence of geitonogamy. The data presented here, together with those available in the literature, reveal that most ontogenetic, micromorphological, and anatomical floral features are uniform for the four sections studied of Anthurium. Part of the variations found here, when compared to the current Anthurium phylogeny, indicates diagnostic characteristics for A. sect. Urospadix (Chapter 1) and other evolutionary branches (Chapter 2). In addition, aspects of floral biology (Chapter 3), such as the synchrony of both staminate and pistillate phases, the release of floral scent by the tepals, and the direction of the male anthesis within the spadix, increase the knowledge about the floral biology in Anthurium and contribute with data for future studies, mainly, on pollination biology of Brazilian species.
Anthurium is the largest genus of Araceae with 950 endemic Neotropical species. In Brazil, the genus comprises 133 species circumscribed mainly within Anthurium sect. Urospadix and A. sect. Pachyneurium, as well as within A. sect. Dactylophyllium and A. sect. Tetraspermium. The ontogenetic, micromorphological, anatomical and floral biology studies of Anthurium can help with significant characters for its taxonomy and systematic, which are based predominantly on foliar morphological features. In this Thesis we analyzed 20 species belonging to four sections of Anthurium, using stereomicroscope, and light, scanning confocal laser and scanning electron microscopies. In Chapter 1, we evaluated the use of ontogenetic, micromorphological and anatomical floral characters, mainly of the perigone and androecium, in the selected sections/clades of Anthurium. We highlight the anatomical characterization of the osmophores, as well as the variation in the shape of outer periclinal wall and in the content presented by the epidermal cells; variation in the overlapping of the outer tepals in the floral bud and in the exposure of the stamens were also pointed out. In Chapter 2, we verified that the vasculature of the perigone and the androecium were uniform amongst the sections studied. However, two patterns of gynoecial vasculature were described: carpels vascularized by synlateral bundles alone (Pattern A), shared by the majority of species studied, and carpels vascularized by both dorsal and synlateral bundles (Pattern B), which occurs in A. affine (A. sect. Pachyneurium), A. obtusum and A. scandens (A. sect. Tetraspermium). Pattern B is a new feature for the genus. In Chapter 3, our main objective was to investigate the separation of both staminate and pistillate phases within the flowers (intrafloral dichogamy) and among flowers of the same plant (interfloral dichogamy). Our data show that complete intrafloral dichogamy occurs in all species studied, except A. scandens (A. sect. Tetraspermium) and A. solitarium (A. sect. Pachyneurium series Pachyneurium), in which we observed, for the first time, the synchrony of both staminate and pistillate phases, suggesting the possible occurrence of geitonogamy. The data presented here, together with those available in the literature, reveal that most ontogenetic, micromorphological, and anatomical floral features are uniform for the four sections studied of Anthurium. Part of the variations found here, when compared to the current Anthurium phylogeny, indicates diagnostic characteristics for A. sect. Urospadix (Chapter 1) and other evolutionary branches (Chapter 2). In addition, aspects of floral biology (Chapter 3), such as the synchrony of both staminate and pistillate phases, the release of floral scent by the tepals, and the direction of the male anthesis within the spadix, increase the knowledge about the floral biology in Anthurium and contribute with data for future studies, mainly, on pollination biology of Brazilian species.
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Palavras-chave
Androceu, Dicogamia, Dimeria, Gineceu, Osmóforos, Perigônio, Pothoideae, Androecium, Dichogamy, Dimery, Gynoecium, Osmophore, Perigone