Thália Gama - Academia.edu (original) (raw)

Papers by Thália Gama

Boletim do Museu Paraense Emílio Goeldi - Ciências Naturais, 2021

Este trabalho aborda o estudo dos grãos de pólen de Polygalaceae e Polygonaceae na ilha de Algodo... more Este trabalho aborda o estudo dos grãos de pólen de Polygalaceae e Polygonaceae na ilha de Algodoal/Maiandeua, representadas, respectivamente, pelas espécies Polygala adenophora DC., P. monticola Kunth, P. spectabilis DC., P. variabilis Kunth, Coccoloba latifolia Lam. e C. ramosissima Wedd. Grãos de pólen retirados de botões florais de exsicatas foram acetolisados, medidos, descritos e fotomicrografados em microscopia de luz e eletrônica de varredura. Os grãos de pólen de Polygalaceae variam de médios a grandes, de subprolatos a prolatos esferoidais, de 9 (-10) (-13) (-16)-colporados, de superfície psilada a perfurada. Os grãos de pólen de Polygonaceae são pequenos, prolatos, 3-colporados, de superfície microrreticulada. Com objetivo de separar as espécies, com base na ornamentação da exina, uma chave foi elaborada.

Euphorbiaceae s.l. are distributed in the most varied types of vegetation and habitat, being one ... more Euphorbiaceae s.l. are distributed in the most varied types of vegetation and habitat, being one of the biggests, most complexs and diversified families in the angiosperms. Its classification was discussed during long time by many authors and with the phylogenetic analyses was proved its polyphyletic origin, bearing the dissolution in six distinct families: Phyllanthaceae, Picrodendraceae, Putranjivaceae, Pandaceae, Peraceae e Euphorbiaceae s.s. Considering the floral diversity of these families, fours species were selected to this study, aiming to sample the different groups: Phyllanthus urinaria (Phyllanthaceae), Piranhea trifoliata (Picrodendraceae), Alchornea sidifolia (Euphorbiaceae s.s.) and Microdesmis caseariifolia (Pandaceae). There are few detailed literature about the floral structure of the representants from the allied families of Euphorbiaceae s.l., which makes difficult the accurate usage of the floral characters in studies about systematics and evolution of these groups. Furthermore, information on the functional implications of these characteristics in the biology of the species are limited. In this context, the aim of this work was analyse the floral morphology, with an emphasis on the development patterns, vascularization and secretory structures. For this purpose, floral buds and flowers in different stages of development were fixed, dehydrated, embedded in Paraplast or historesin, sectioned and stained, besides the SEM and TEM analysis that helped on the investigation of the floral ontogenesis and the nectariferous tissue. As main results of the structural analysis, we found that Phyllanthus urinaria has sepals and petals, as well Piranhea trifoliata, both from the clade Phyllanthaceae + Picrodendraceae. Then, flowers from these groups should be studied from its origin and vascularization to have a better understanding of the evolutionary path of the perianth in these families. Piranhea trifoliata also have staminodes that may indicate a transitional process during the evolution of the group. In Alchornea sidifolia we found development patterns that explain the formation of characteristics of anemophilous plant, such as the production of more flowers in the male inflorescences than the more compact and fewer flowered female inflorescences, the presence of unisexual flowers with reduced perianth, absence of nectaries, and female flowers with extensive stigmatic receptive surface. This species also has a peculiar characteristic regarding the number of carpels, which is generally three in the Euphorbiaceae and Malpighiales, even though A. sidifolia has two carpels. Microdesmis caseariifolia displayed variation in the number of stamens, shown a placental obturator and a pistilode, and all these features are novelties to the Pandaceae. This study adds to the floral knowledge of the different families, as well as enable to raise issues to be addressed in future studies about the structure and evolution of floral characters in Malpighiales.

Brazilian Journal of Botany, 2019

Most Euphorbiaceae are insect pollinated, but in Acalyphoideae a considerable number of species a... more Most Euphorbiaceae are insect pollinated, but in Acalyphoideae a considerable number of species are wind pollinated and generally have inconspicuous monochlamydeous flowers with red styles and multifid or laciniate stigmata. Alchornea is within the basal alchorneoid clade, and its flowers are more conspicuous in the group. The aim of this study was to investigate the ontogeny, anatomy and vasculature of flowers of Alchornea sidifolia Müll. Arg., species from the Alchorneoids clade, a basal clade sister of the "core acalyphoid," in order to find structural aspects related to wind pollination. Flowers and buds of A. sidifolia were embedded in Paraplast and sectioned with a rotary microtome for analysis under light microscopy. SEM was performed for additional structural and ontogenetic data. Alchornea sidifolia is dioecious and has morphologically and functionally unisexual flowers which only share a monochlamydeous, tetramerous perianth, organized in a single whorl of sepals. In the male flower, calyx begins as a ring on the floral meristem in a congenital connation, but in the female one, the calyx has a late synsepaly. Pistillodes and staminodes are absent in the male and female flowers, respectively. The filaments of the stamens are connate at the base for a short extant and free toward the apex. The gynoecium is syncarpous, and the ovary is mostly synascidiate with a short symplicate zone and two long stigmata. Our results highlight the development of features of the inflorescence and flowers of A. sidifolia which in comparison with insect-pollinated Euphorbiaceae display a set of features which are typically associated in many other unrelated angiosperm lineages with the evolution of wind pollination, such as dioecy, production of a higher number of flowers in the male inflorescences than the female inflorescences, unisexual flowers with reduced perianth and no nectaries, male flowers with a variable number of stamens and female flowers with extensive stigmatic receptive surface. We also discuss the presence of two carpels in Alchornea, when most Euphorbiaceae and many other Malpighiales have three, and its relationship with the wind pollination.

The Journal of the Torrey Botanical Society, 2017

Recent studies have shown the laticifers of Apocynaceae, previously classified as nonarticulated,... more Recent studies have shown the laticifers of Apocynaceae, previously classified as nonarticulated, indeed are articulated, anastomosing laticifers whose transverse walls dissolve rapidly and entirely, although doubts about their growth mode still persist. To better understand the mode of laticifer growth and differentiation in this family, we studied its development in Allamanda blanchetii using anatomical and ultrastructural analyses. Our results showed that laticifers are formed by a row of cells that join each other through dissolution of the transverse walls from the center to the periphery. The laticifers originate from ground meristem and procambium; the laticifers in the different tissues connect through lateral fusion, generating a laticifer network. The laticifers occur in the cortex, pith, and vascular system of the shoot, mesophyll, and vascular bundles of the leaves. There is no apical growth, and all the organelles observed in the apices of the laticifers play a role in the production of latex or in the dissolution of the terminal walls between the cells that compose the laticifer. The latex is composed of many metabolites produced mainly in the endoplasmic reticulum and plastids. Mitochondria are abundant, and dictyosomes are scarce. The vacuome is prominent from the start of laticifer differentiation, and many small vacuoles and vesicles transport the secretion from cytosol into the central vacuole, where an emulsion of substances is stored. The articulated, anastomosing laticifers of A. blanchetii have no subcellular mechanism for production of a cell wall in a polarized manner or dissolution of middle lamella of the cells which surround the laticifer tip, proving that there is no intrusive growth in this secretory structure.

Acta Biológica Catarinense, 2015

A mandioca (Manihot esculenta Crantz, Euphorbiaceae) é uma espécie amplamente cultivada no Brasil... more A mandioca (Manihot esculenta Crantz, Euphorbiaceae) é uma espécie amplamente cultivada no Brasil, principalmente pelas comunidades tradicionais da Amazônia, que abrigam em seus roçados grande número de cultivares ainda pouco explorados. Objetivou-se caracterizar a morfologia dos grãos de amido encontrados nas raízes de cinco cultivares de mandioca, procedentes da Floresta Nacional (Flona) de Caxiuanã, Pará, Brasil, a fim de verificar a similaridade entre eles. Os grãos de amido foram medidos, descritos e ilustrados em microscopia de luz e eletrônica de varredura. Constatou-se que são de superfície lisa, não compostos e apresentam as formas mitra, cúpula e arredondada. Embora a morfologia dos grãos de amido tenha se mostrado bastante semelhante entre os cultivares estudados, o tratamento estatístico aplicado evidenciou diferenças quanto ao diâmetro, sendo possível delimitar os cinco cultivares em apenas quatro.

International Journal of Plant Sciences, 2016

Premise of research. Phyllanthus is a pantropical genus and the largest in Phyllanthaceae with a ... more Premise of research. Phyllanthus is a pantropical genus and the largest in Phyllanthaceae with a wide diversity of habits and floral morphologies. The flowers are considered monochlamydeous, but some divergences are found in the literature. The aim of this study was to investigate the floral structure of Phyllanthus urinaria based on ontogenetic, structural, and vascular analyses. Methodology. Flowers and buds of P. urinaria were embedded in Paraplast and sectioned using a rotatory microtome for analysis under LM. SEM was performed for additional structural and ontogenetic data. Pivotal results. The primordia of the sepals are the first structures to be formed in a counterclockwise direction, followed by the petals, which arise in a clockwise direction. Nectaries are formed on the base of the corolla in the staminate and pistillate flowers; then, the two perianth whorls merge, fusing at the base of the adult flowers. The three stamens have filaments postgenitally fused and free anthers. The ovary has three carpels congenitally connate with two ovules hemitropous with one long nucellar beak per locule and styles partially fused. Conclusions. Our results demonstrate for the first time the petaliferous nature of the inner whorl of the perianth in Phyllanthus, based on ontogenetic and anatomical evidence. The presence of a perianth with sepals and petals is a possible synapomorphy of the clade formed by Phyllanthus sect. Emblica + Phyllanthus sect. Urinaria and Breynia, Glochidion, and Sauropus, now under Phyllanthus in the current phylogenetic circumscription of the tribe Phyllantheae.

Anais da Academia Brasileira de Ciências, 2016

Transfer cells are specialized cells that play an important role where there are high energy cost... more Transfer cells are specialized cells that play an important role where there are high energy costs due to facilitation of transmembrane flow of solutes. This study aimed to investigate the ontogenesis, histochemistry and ultrastructure of glandular trichomes focusing on stalk cells and their possible transfer function. Samples of prophylls of axillary buds, calyces of flowers in anthesis, and flower buds in different stages of development were collected, fixed and processed according to the common methods of microscopy. The glandular trichomes are composed of a secretory head with its cells in columnar format. The stalk is formed by two layers of cells, with the upper layer composed of cuboidal cells where the wall starts to thicken at the beginning of the pre-secretory phase. The secretion is heterogeneous, releasing glucose, other carbohydrates, lipids and phenolic compounds, with two types of release - eccrine and granulocrine. These trichomes are functionally termed as nectaries...

Acta Amazonica, 2015

Glandular trichomes play a major role in the morphological characterization of the Bignoniaceae. ... more Glandular trichomes play a major role in the morphological characterization of the Bignoniaceae. Due to their great diversity of forms and functions, this study aimed to inventory the glandular trichomes present in the aerial vegetative axis of Amphilophium magnoliifolium, Martinella obovata and Stizophyllum riparium, analyze their structure and register the participation of ants in these plants. Fresh samples from the nodal region, petiole and from medium to apical regions of the leaflet blade were fixed and processed according to usual methods in light and scanning electron microscopies. The glandular trichomes found were: peltate, capitate, stipitate, and patelliform/cupular. Peltate trichomes are the most abundant ones and present the most uniform distribution. Patelliform/cupular trichomes occur at specific regions, such as prophylls, leaflet blade and nodal regions. Martinella obovata is the only species that presents capitate and stipitate trichomes, which are widely distribu...

Revista de Biología Tropical, 2015

Plant structures that secrete lipids and phenolic compounds are often associated with the protect... more Plant structures that secrete lipids and phenolic compounds are often associated with the protection and development of organs against desiccation, in addition to the protection they provide against animals, as the capitate trichomes of Adenocalymma magnificum. Understanding the glandular activities that occur in these trichomes has required the study of their ontogeny, structure, ultrastructure and histochemical aspects; the interpretation of their ecological functions or evolutionary history is complicated by the scarcity of reports on calicinal trichomes that are not nectar-secreting. Samples of floral calyx in anthesis and flower buds at different stages of development were fixed and processed according to the methods for light and electron microscopy. The trichomes are randomly distributed throughout the entire inner surface of the calyx and are also visible on the flower buds. These capitate glandular trichomes were composed of a peduncle, having up to nine cells, and a multicellular secretory head with their cells in columnar format and arranged in disc form. The collar cell, which is under the secretory head, divides anticlinally and arranges itself side by side with the mother cell. As they develop, they bend with some of them becoming adpressed to the calyx. Histochemical tests indicate that the secretory head cells produce lipid substances, acidic lipids and phenolic compounds. In the secretory head, the vacuome is dispersed and the cytoplasm possesses a great number of smooth endoplasmic reticulum and leucoplasts, organelles involved in the production of osmiophilic substances. In some regions of the secretory cells, cuticle detachment was observed; however, the accumulation of secretions was not observed. This study describes, for the first time, the origin, development, and secretion process of the calicinal trichomes of Adenocalymma magnificum, showing that production of lipophilic substances is important for this plant, possibly the trichomes may be involved in the plant's chemical defense against insects, offering protection against herbivores.

Brazilian Journal of Botany, 2013

ABSTRACT Ontogeny, histochemistry, and structure of glandular trichomes inBignonia aequinoctialis... more ABSTRACT Ontogeny, histochemistry, and structure of glandular trichomes inBignonia aequinoctialis(Bignoni-aceae). Glandular trichomes commonly occur in Big-nonieae; however, because ontogenetic studies are scarce much still needs to be learned and understood about the function of these secretory structures in the species of the tribe. Therefore, the present study aimed to investigate not only the secretion and function of the glandular trichomes of B. aequinoctialisbut also their occurrence and devel-opment. Samples of leaflets, prophylls of the axillary buds, floral calyx in anthesis, and flower buds in different stages of development were collected, fixed, and processed according to the usual methods for light microscopy and scanning electron microscopy. Diverse ants were found in all the plants; ants located near to the trichomes were collected. B. aequinoctialishas two types of glandular trichomes on the aerial vegetative axis and the reproductive axis: patelliform and peltate. Both are distributed in large quantities in the early stages of the plant’s development, exhibit asynchronous development, and have protodermic origin. The peltate glandular trichome consists of a peduncle cell and several cells in the head, which characterize the head as a multicellular secretory portion in disk shape. The patelliform glandular trichome is formed by one large peduncle cell and a secretory epidermis uniseriate, in columnar form. Histochemical tests identified a sugary secretion from the patelliform glandular trichomes, which serves as the ants’ reward. Thus, these glandular trichomes have been shown to have an important role in the insect–plant mutualistic relationship.

Plant Cell Reports, 2019

Key message Blue and yellow light affected metabolism and the morphology. Blue and red promote th... more Key message Blue and yellow light affected metabolism and the morphology. Blue and red promote the DOXP/MEP pathway. ADS gene expression was increased in plants cultivated under blue, promoting artemisinin content. Abstract Artemisinin-based combination therapies are the most effective treatment for highly lethal malaria. Artemisinin is produced in small quantities in the glandular trichomes of Artemisia annua L. Our aim was to evaluate the effect of light quality in A. annua cultivated in vitro under different light qualities, considering anatomical and morphological changes, the volatile composition, artemisinin content and the expression of two key enzymes for artemisinin biosynthesis. Yellow light is related to the increase in the number of glandular trichomes and this seemed to positively affect the molecular diversity in A. annua. Yellow light-stimulated glandular trichome frequency without triggered area enhancement, whereas blue light stimulated both parameters. Blue light enhanced the thickness of the leaf epidermis. The B-promoting effect was due to increased cell size and not to increased cell numbers. Green and yellow light positively influenced the volatile diversity in the plantlets. Nevertheless, blue and red light seemed to promote the DOXP/MEP pathway, while red light stimulates MVA pathway. Amorpha-4,11-diene synthase gene expression was significantly increased in plants cultivated under blue light, and not red light, promoting artemisinin content. Our results showed that light quality, more specifically blue and yellow light, positively affected secondary metabolism and the morphology of plantlets. It seemed that steps prior to the last one in the artemisinin biosynthesis pathway could be strongly influenced by blue light. Our work provides an alternative method to increase the amount of artemisinin production in A. annua without the use of transgenic plants, by the employment of blue light. Keywords Artemisia annua • Artemisinin • Glandular trichome • Light quality • Volatile Abbreviations ACT Artemisinin combination therapies ADS Amorpha-4,11-diene synthase B Monochromatic blue light CRY Cryptochrome CYP71AV1 Cytochrome P450 monooxygenase D Darkness dNTPs Deoxyribonucleoside 5′-triphosphate DOXP/MEP 2Cmethyl-d-erythritol-4-phosphate pathway DTT Dithiothreitol FAA 37% formaldehyde, glacial acetic acid, and 70% ethanol solution G Monochromatic green light Gl.T Glandular trichomes LED Light-emitting diode LRI Linear retention indices MS Murashige and Skoog MVA Mevalonic acid pathway Communicated by Stefan Schillberg.