Comparative leaf anatomy of four species of Bromelioideae (Bromeliaceae) occurring in the Atlantic Forest, Brazil

Bromeliaceae, comprising 3172 species, is one of the most important families of the Brazilian Atlantic Forest owing to its high degree of endemism and occurrence in different habitats. The subfamily Bromelioideae is the most representative of Bromeliaceae and the best represented in the state of Minas Gerais, Brazil, with 120 species. The objective of this study is to compare the leaf anatomy of four species found in two areas of the Atlantic Forest: Serra do Brigadeiro State Park, Minas Gerais, Brazil ( Wawra and (Baker) Leme) and a forest fragment located within Bom Sucesso Farm, Viçosa, Minas Gerais, Brazil ( E. Morren and Bertol.), relating environmental characteristics to the habit. Leaf samples were studied using light and scanning electron microscopy and histochemical tests with Sudan, phloroglucinol, and ruthenium red stains. Leaves of and showed several adaptations to the epiphytic habit, including scales on both surfaces, thickened epidermal cell walls, presence of silica bodies, hypodermis with sclerified cells, water-storing tissue (hydrenchyma), and air channels formed by stellate cells in the chlorenchyma. The epiphytic species and the terrestrial species have similar overall structure, including a well-developed parenchyma and extravascular fiber groups. Leaves of the terrestrial species and the epiphytic species also show structural similarities, such as lack of extravascular fibers and less developed parenchyma. Similar characteristics in species from different habitats may either reflect microclimatic conditions under which these species occur or genetically fixed characteristics.Les Bromeliaceae, comprenant 3172 espèces, constituent une des familles les plus importantes de la forêt atlantique brésilienne par son fort degré d'endémisme et par sa présence dans différents habitats. La sous-famille des Bromelioideae, la plus représentative des Bromeliaceae, est la mieux représentée dans l'état de Minas Gerais, au Brésil, avec 120 espèces. L'objectif de l'étude consiste à comparer l'anatomie foliaire de quatre espèces trouvées dans deux régions de la forêt atlantique : parc de l'état « Serra do Brigadeiro », MG, Brésil ( Quesnelia strobilispica Wawra et Wittrockia gigantea (Baker) Leme), et un fragment forestier localisé sur la ferme « Bom Sucesso », Viçosa, MG, Brésil ( Billbergia euphemiae E. Morren et Bromelia antiacantha Bertol.), en reliant les caractéristiques environnementales avec l'habitat. Les auteurs ont étudié les feuilles à l'aide de la microscopie photonique et électronique par balayage, ainsi que des colorations au Sudan, phloroglucinol, et rouge de ruthénium. Les feuilles du B. euphemiae et du W. gigantea montrent plusieurs adaptations à l'habitat épiphyte, incluant des écailles sur les deux surfaces, des parois cellulaires épaissies, la présence de corps siliceux, un hypoderme avec des cellules sclérifiées, des tissus accumulateurs d'eau (hydranchymes) et des canaux aérifères formés par des cellules stellées, dans le chlorenchyme. L'espèce épiphyte, B. euphemiae, et l'espèce terrestre, Q. strobilispica, possèdent en général des structures similaires, incluant un parenchyme bien développé et des groupes de fibres extra-vasculaires. Les feuilles de l'espèce terrestre, B. antiacantha, et de l'espèce épiphyte, W. gigantea, montrent également des similarités de structures comme l'absence de fibres extra-vasculaires et un parenchyme moins développé. La similitude des caractères chez des espèces provenant de différents habitats peut refléter soit les conditions microclimatiques sous lesquelles ces espèces se développent, ou encore des caractéristiques génétiques fixées

Distribution, structural and ecological aspects of the unusual leaf nectaries of Calolisianthus species (Gentianaceae)

Nectaries in leaves of Gentianaceae have been poorly studied. The present study aims to describe the distribution, anatomy, and ecological aspects of extrafloral nectaries (EFNs) of three Calolisianthusspecies and in particular the ultrastructure of EFNs in Calolisianthus speciosus during leaf development, discussing its unusual structure. Leaves of Calolisianthus species were fixed and processed by the usual methods for studies using light, scanning microscopy and transmission electron microscopy (TEM). Ion chromatography was used to analyze the nectar exudates of C. speciosus. The distribution patterns of nectar secretion units were analysed by ANOVA and t-tests. Two EFNs that can be seen macroscopically were observed at the bases of C. speciosus and C. pendulus leaves. Such large nectaries are absent there in C. amplissimus. Another similarly large EFN is observed at the apex of each leaf in all species. The EFNs at the base of the young leaves in C. speciosus are visited by ants during the rainy season. EFNs are formed by several nectar secretory units (nectarioles) that are present throughout the leaves. Each nectariole is formed by rosette cells with a central channel from which the nectar is released. Channels of old C. speciosus and C. pendulus EFNs were obstructed by fungi. TEM of EFNs in young leaves showed cytoplasms with secretion, small vacuoles, mitochondria, cell wall ingrowth, and plasmodesmata. TEM of EFNs in old leaves demonstrated dictyosomes, plastids, mitochondria, segments of endoplasmatic reticulum, and lipid droplets. The nectar contains sucrose, glucose and fructose

Biochemical, physiological and anatomical assessment of atmospheric pollutants effects upon restinga plant species

Com o objetivo de avaliar os efeitos tóxicos do ferro particulado e do dióxido de enxofre liberados por uma usina de pelotização, localizada no município de Anchieta, ES, sobre parâmetros fisiológicos, bioquímicos e anatômicos, foram determinados os efeitos dos poluentes atmosféricos mediante metodologia de bioindicação ativa e passiva. As espécies avaliadas no biomonitoramento ativo, Eugenia uniflora L. (Myrtaceae) e Clusia hilariana Schlecht. (Clusiaceae), foram colocadas em estações padronizadas e distribuídas em diferentes distâncias: 200 m, 500 m, 800 m, 1400 m e 1700 m em relação à fonte emissora, durante 7 meses. Em experimento simultâneo, as mudas inseridas num solo removido de uma usina de pelotização foram submetidas à chuva ácida simulada constituída de H 2 SO 4 , com pH 3,0 e à chuva controle com pH 6,5, durante 40 dias. Na bioindicação passiva, indivíduos das espécies: Byrsonima sericea DC. (Malpighiaceae), Cordia verbenacea DC. (Boraginaceae) e Psidium guineense SW. (Myrtaceae) foram avaliados numa mata remanescente de restinga, localizada a 200 m da usina (local exposto) e no Parque Estadual Paulo César Vinha (local não-exposto), durante um ano. E. uniflora recebeu deposição de maior quantidade de ferro particulado por área foliar do que C. hilariana, não variando quanto às distâncias da fonte emissora nas duas espécies. Os maiores teores foliares de ferro total foram verificados a 200 m da fonte emissora, nas duas espécies vegetais, enquanto que o maior teor de enxofre total foliar foi observado em E. uniflora, a 800 m e em C. hilariana, a 200 m da fonte emissora. Não se observou variação em altura nas duas espécies vegetais avaliadas e o número de folhas foi menor apenas a 800 m e 1700 m de distância em C. hilariana. O número e a percentagem de folhas cloróticas e necróticas, assim como o índice de fitotoxicidade de cloroses nas duas espécies aumentaram com o prolongamento do tempo de exposição às emissões da usina. Em E. uniflora, a percentagem de folhas cloróticas e necróticas não se modificou com a distância da fonte emissora, enquanto que em C. hilariana, as maiores médias foram observadas a partir de 500 m. Nas duas espécies, o teor de clorofila diminuiu com o tempo de exposição e apenas em plantas de E. uniflora localizadas a 800 m da fonte emissora foram observados maiores teores de clorofila. As plantas de C. hilariana localizadas a 200 m e 500 m da fonte emissora apresentaram maior permeabilidade de suas membranas celulares, que se relacionou com o teor foliar de enxofre. As plantas de C. hilariana apresentaram condutância estomática (g s ), a transpiração (E) e a assimilação líquida de CO 2 (A) mais elevadas nas estações mais próximas à usina emissora, embora isto não tenha contribuído para o aumento da massa seca total. A relação trocas gasosas e teor foliar de enxofre sugeriu que C. hilariana acumulou grande quantidade de enxofre enquanto que E. uniflora praticamente não absorveu o enxofre emitido pela usina de pelotização. Ambas as espécies são bioindicadoras de reação, podendo ser usadas como bioindicadoras ativas de poluição por deposição particulada e dióxido de enxofre. Em relação ao experimento com chuva ácida, nenhuma das espécies apresentou variação na altura das mudas tratadas em relação ao controle, enquanto o índice de fitotoxicidade de necroses foi maior nas plantas de E. uniflora expostas à chuva ácida. Os teores de clorofila a, de clorofila b e de carotenóides foram reduzidos em E. uniflora após o tratamento, enquanto que a relação F v /F m foi maior nas plantas tratadas. Em C. hilariana, nenhum destes parâmetros foi alterado com a chuva ácida. A g s , E e A não variaram nas plantas tratadas em relação ao controle, nas duas espécies avaliadas, após as 40 chuvas simuladas. Nenhuma das espécies mostrou alteração na permeabilidade de suas membranas. Em E. uniflora, apenas a atividade da peroxidase aumentou com o tratamento, enquanto que em C. hilariana, as atividades da dismutase do superóxido, da peroxidase e da catalase aumentaram após as 40 simulações. Nas três espécies avaliadas no biomonitoramento passivo, o teor de ferro foliar foi maior no local exposto às emissões da usina e o teor foliar de enxofre variou nas diferentes espécies analisadas. Os efeitos mais marcantes das deposições da usina sobre as espécies avaliadas no biomonitoramento passivo foram: Em B. sericea, maior teor de clorofila, menor temperatura foliar, maior número de folhas; em C. verbenacea, maior teor de clorofila, maior temperatura foliar, menor número de folhas, flores e frutos; em P. guineense, menor teor de clorofila, maior diferencial de temperatura entre a folha e o ar, maior lançamento de folhas, menor número de folhas. Não foram verificadas flores e frutos neste local. C. verbenacea acumulou maior quantidade de ferro que as demais espécies ocorrendo maior deposição nas reentrâncias nas bases dos tricomas glandulares. As plantas de B. sericea apresentaram menor conteúdo de ferro provavelmente, devido a presença de hipoderme e tricomas malpiguianos, enquanto que em P. guineense, a proteção parece ter sido viabilizada pela hipoderme.In order to evaluate the toxic effects of particulate iron and sulfur dioxide, emitted by an iron ore factory located at Anchieta county, ES, passive and active biomonitoring methodologies were tested. Biochemical, physiological and anatomical parameters were evaluated on native plant species of restinga. On the active biomonitoring test, Eugenia uniflora L. (Myrtaceae) and Clusia hilariana Schlecht. (Clusiaceae) saplings were placed, during seven months, in standardized strands arranged at 200 m, 500 m, 800 m, 1400 m and 1700 m from the souce emissions. Simultaneously, an experiment with simulated acid rain was tested on the two species, cultivated in original soil, at Universidade Federal de Viçosa. The saplings were submitted, for 40 th days, to acid rain pH 3.0 and pH 6.5 control). For the passive bioindicating test saplings of Byrsonima sericea DC. (Malpighiaceae), Cordia verbenacea DC. (Boraginaceae) and Psidium guineense SW. (Myrtaceae) were assessed during one year, in two locations: at a remaining fragment of restinga nearby the ore factory (exposed site) and at the Parque Estadual Paulo César Vinha (control site). E. uniflora received a greater amount of particulate iron, per foliar area, than C. hilariana, which did not change with the distance from the emission source. To both species, the highest total iron content in the leaves was detected at 200 m from the emission source. The sulfur content in the leaves, however, was higher at 800 m and 200 m, for E. uniflora and C. hilariana, respectively. There was no variation on the plant height, for both species, and the number of leaves only decreased on C. hilariana, at 800 and 1700 m from the source. The amount and the percentage of chlorotic and necrotic leaves, as well as the chlorosis phytotoxicity index, on both species, increased with the time exposure to the emissions. The necrotic and chlorotic leaf percentages of E. uniflora did not vary with the distance from the emission source, while C. hilariana showed the highest percentages beyond the 500 m from the source. For both species, the chlorophyll content decreased with the time exposure, but in E. uniflora this content was higher at 800 m from de emission source. Plants of C. hilariana standing at 200 m and 500 m, from the emission source, displayed a higher membrane permeability which was related to the sulfur content in the leaves. The stomatal conductance (g s ), the transpiration (E) and the net CO 2 assimilation (A) of Clusia hilariana was higher at those sets near the factory, however the total dry weight did not vary. The foliar sulfur content and gas exchange traids in C. hilariana, suggested that this specie accumulated greater quantify of sulfur, probably from the factory emissions, than E. uniflora. Both species studied in this essay are reaction bioindicators and can used as active bioindicators of particulate and sulfur dioxide emissions. In the acid rain simulation test, none of the species showed variation on the plant height, but in E. uniflora displayed a higher necrosis phytotoxicity index when the sapling were exposed to the lowest pH rain. Plants of E. uniflora, exposed to pH 3.0 rain had their chlorophylls a, b and carotenoids contents reduced after the treatment. However, the F v /F m ratio of those plants increased. The same parameters, in C. hilariana, did not suffer any alteration after the rain simulation. The gas exchange constituents, g s , E and A, did not alter in none of the treatment for both species, even after 40 days. The membrane permeability, in both species, also remained unaltered. In E. uniflora, only the peroxidase activity enhanced with the treatment exposed, while in C. hilariana all the enzymes tested, had their activity improved at the end of the pH 3.0 treatment. All three species, on the passive biomonitoring test, showed a higher iron content on those saplings kept in the exposed site, while the sulfur content in the leaves varied according to the species. The effects of the factory depositions was remarkable different among the species, causing: in B. sericea an elevation on the chlorophyll content, lower foliar temperature and higher number of leaves; in C. verbenacea an elevation on chlorophyll content, lower foliar temperature, lower number of leaves, flowers and fruits; in P. guineense lower chlorophyll content, higher leaf air temperature difference, greater release of new shoots, but fewer leaves, and no flowers or fruits. C. verbenacea accumulated higher quantify of iron than the other species, mainly deposited between the gaps on the trichomes base. Plants of B. sericea had the lowest iron content, probably due to the presence of a hypoderm, malpighians trichomes, while in P. guineense the protection was guaranteed only by the a hypoderm.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Morphoanatomical and biochemical changes in Zeyheria tuberculosa exposed to glyphosate drift

When glyphosate is applied, some of the herbicide can reach adjacent vegetation and impact the natural plant community structure and diversity over the long term. This study evaluated the response of leaves of Zeyheria tuberculosa (Vell.) Bureau ex Verl. (Bignoniaceae) to the herbicide glyphosate. Plants were exposed to aerial applications of the herbicide at concentrations of 0, 360, 720, 1080, or 1440 g acid equivalent (a.e.)·ha 1. The concentrations of shikimic acid in leaves of the herbicide-treated plants were always higher than the controls. Visual symptoms became apparent four days after the application of 720 g·ha 1. Glyphosate induced an increase in malondialdehyde in Z. tuberculosa leaves. The lowest levels of chlorophyll a were found for the three last applied doses, and protein content decreased with the glyphosate treatment. Necrosis was observed on the epidermis and in the mesophyll. Glandular trichomes were also plasmolyzed. On the midrib there was plasmolysis of non-lignified cells. Micromorphologically, there were cell plasmolysis and rupture of glandular trichomes. Thus, glyphosate is phytotoxic to Z. tuberculosa by causing biochemical, anatomical, and morphological changes. The morphoanatomical injuries found on Z. tuberculosa were severe, suggesting that the presence of glyphosate can irreversibly affect this species and compromise its survival.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Iron plaque formation and morphoanatomy of roots from species of restinga subjected to excess iron

The restingas, a sandy coastal plain ecosystem of Brazil, have received an additional amount of iron due to the activity of mining industries. The present study aims to characterize morphoanatomically and histochemically the iron plaque formation on roots of Ipomoea pes-caprae L. and Canavalia rosea DC, cultivated in hydroponic solution with and without excess iron. The iron plaque formation as well as changes in the external morphology of the lateral roots of both species were observed after the subjection to excess iron. Changes in the nutrient uptake, and in the organization and form of the pericycle and cortex cells were observed for both species. Scanning electron microscopy showed evident iron plaques on the whole surface of the root. The iron was histolocalized in all root tissues of both species. The species of restinga studied here formed iron plaque in their roots when exposed to excess of this element, which may compromise their development in environments polluted by particulated iron

Sensibility of Spondias purpurea L. (Anacardiaceae) exposed to fluoride-simulated fog

Fluoride is the atmospheric pollutant with the highest phytotoxicity arising from aluminum smelting fertilizers, glass and, ceramic industry. The most affected plant organ is the leaf, in which the fluoride penetrates through two main ways: absorption by epidermis cuticle or absorption by stomata. Species susceptible to fluoride are potential tools in bioindicator studies because they provide a means for detecting the presence of the pollutant in the environment at a low cost. The aim of this study is to evaluate the sensibility of Spondias purpurea L. (Anacardiaceae) to fluoride through the simulated fog. Simulation was performed by applying 500 ml of solution containing 15 mg L−1 of potassium fluoride per plant for 20 min daily and for 10 consecutive days. The data of leaflet abscission, visual damage, and climate conditions were recorded daily. At the end of the experiment, data from the cell death analysis, electrolyte leakage determination, and accumulation of the fluoride in the dried matter were collected. Moreover, samples for phenolic compound accumulation, anatomical, and micromorphological analyses were collected. After 24 h, the appearance of visible damage was observed in the leaves with fluoride treatment. This damage consisted, mostly, of necrosis, chlorosis, and leaf apical shriveling. The necroses manifested in gray and brown discoloration. Leaf abscission was intense in the young leaves. Microscopic damage consisted of protoplast retraction, phenolic compound accumulation, collapse, hyperplasia, and cell rupture. Turgidity loss, epicuticular wax erosion, and damage of stomata and trichomes beyond the presence of fungal hyphae were noted in the epidermis. Evans Blue detected dead cell groups in the transition region between the necrosis and the apparent healthy area. Fluoride affected the selective permeability of the membrane, which was observed in this study according to the high rate of electrolyte leakage. Plants exposed to fluoride accumulated 14.48 times more fluoride in their leaves than plants in the control group. It follows that S. purpurea is susceptible to fluoride and responds quickly to the presence of this pollutant. Marginal and apical necrosis, presence of phenolic compounds, fluoride accumulation, anatomical alterations, and leaflet abscission in the young leaves are biomarkers of fluoride effects in this species. Therefore, S. purpurea is potentially useful in biomonitoring programs

Leaf structural traits of two Restinga plant species with different resistance pattern to iron toxicity

Iron mining activities are a source of particulate iron, which contaminates soil and plants of Restinga biome (Brazil). To investigate the possible effects of iron toxicity to Ipomoea pes-caprae and Canavalia rosea leaves, plants were submitted to different exposure times (12, 36, 108 and 228 hours) and iron concentrations (0.5 or 150 mg L-1, Fe2+ as FeSO4.7H2O). After 108 hours C. rosea leaves were chlorotic while I. pes-caprae leaves presented venal chlorosis and bronzing after 228 hours, both from iron excess treatment. The anatomical alterations in I. pes-caprae were more intense and appeared earlier than in C. rosea, after 36 hours exposed to iron excess. The leaf epidermal cells of I. pes-caprae presented alterations in organization, size and shape and for both species the epicuticular wax was altered and wax rupture occurred close to the stomata. The positive staining for the presence of iron in leaf tissues matches with damaged areas in I. pes-caprae leaves, indicating direct iron toxicity. I. pes-caprae was the species with the most severe symptoms while C. rosea was the most resistant one. The results support that over time, the emission of particulate matter may negatively impact the ecological succession and biodiversity of Restinga.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Structural adaptation and anatomical convergence in stems and roots of five plant species from a “Restinga” sand coastal plain

Coastal areas present limiting environmental conditions, such as high soil salinity, intense winds, elevated temperature and coastal flooding, which may be related to adaptive anatomical characters. This study aims to evaluate the anatomy of the stems and roots of Restinga plants (eudicots: Blutaparon portulacoides, Canavalia rosea, Ipomoea pes-caprae and Scaevola plumieri; monocot: Remirea maritima) and their relationship to parameters of the microenvironment. These five species were selected because they are dominant and present great occurrence in Restinga vegetation nearest to the sea. Stems and roots of five species (n = 5) were fixed and submitted to standard techniques for analyzing under light microscope. Wind velocity, air temperature, air relative humidity and evaporation level were evaluated close to individuals and above them. The nutritional conditions from rhizosphere were also estimated. The winds were weak close to individuals, while the temperature was higher than compared to measurements above individuals. Minor differences of the soil were noted between areas close and far from the plants. Seven anatomical characters may be related to adaptability to the stressful conditions, as stem succulence, root aerenchyma, root starch reserves and epidermal cell of the stems with thick outer periclinal walls, however there was little convergence between species. Aerenchyma and water reserve tissue were the most frequent anatomical traits. In contrast, elevated cortex lignification in roots was the lowest occurrence trait, being a specific feature of the monocot

Comparative leaf anatomy of four species of Bromelioideae (Bromeliaceae) occurring in the Atlantic Forest, Brazil

Bromeliaceae, comprising 3172 species, is one of the most important families of the Brazilian Atlantic Forest owing to its high degree of endemism and occurrence in different habitats. The subfamily Bromelioideae is the most representative of Bromeliaceae and the best represented in the state of Minas Gerais, Brazil, with 120 species. The objective of this study is to compare the leaf anatomy of four species found in two areas of the Atlantic Forest: Serra do Brigadeiro State Park, Minas Gerais, Brazil ( Wawra and (Baker) Leme) and a forest fragment located within Bom Sucesso Farm, Viçosa, Minas Gerais, Brazil ( E. Morren and Bertol.), relating environmental characteristics to the habit. Leaf samples were studied using light and scanning electron microscopy and histochemical tests with Sudan, phloroglucinol, and ruthenium red stains. Leaves of and showed several adaptations to the epiphytic habit, including scales on both surfaces, thickened epidermal cell walls, presence of silica bodies, hypodermis with sclerified cells, water-storing tissue (hydrenchyma), and air channels formed by stellate cells in the chlorenchyma. The epiphytic species and the terrestrial species have similar overall structure, including a well-developed parenchyma and extravascular fiber groups. Leaves of the terrestrial species and the epiphytic species also show structural similarities, such as lack of extravascular fibers and less developed parenchyma. Similar characteristics in species from different habitats may either reflect microclimatic conditions under which these species occur or genetically fixed characteristics.Les Bromeliaceae, comprenant 3172 espèces, constituent une des familles les plus importantes de la forêt atlantique brésilienne par son fort degré d'endémisme et par sa présence dans différents habitats. La sous-famille des Bromelioideae, la plus représentative des Bromeliaceae, est la mieux représentée dans l'état de Minas Gerais, au Brésil, avec 120 espèces. L'objectif de l'étude consiste à comparer l'anatomie foliaire de quatre espèces trouvées dans deux régions de la forêt atlantique : parc de l'état « Serra do Brigadeiro », MG, Brésil ( Quesnelia strobilispica Wawra et Wittrockia gigantea (Baker) Leme), et un fragment forestier localisé sur la ferme « Bom Sucesso », Viçosa, MG, Brésil ( Billbergia euphemiae E. Morren et Bromelia antiacantha Bertol.), en reliant les caractéristiques environnementales avec l'habitat. Les auteurs ont étudié les feuilles à l'aide de la microscopie photonique et électronique par balayage, ainsi que des colorations au Sudan, phloroglucinol, et rouge de ruthénium. Les feuilles du B. euphemiae et du W. gigantea montrent plusieurs adaptations à l'habitat épiphyte, incluant des écailles sur les deux surfaces, des parois cellulaires épaissies, la présence de corps siliceux, un hypoderme avec des cellules sclérifiées, des tissus accumulateurs d'eau (hydranchymes) et des canaux aérifères formés par des cellules stellées, dans le chlorenchyme. L'espèce épiphyte, B. euphemiae, et l'espèce terrestre, Q. strobilispica, possèdent en général des structures similaires, incluant un parenchyme bien développé et des groupes de fibres extra-vasculaires. Les feuilles de l'espèce terrestre, B. antiacantha, et de l'espèce épiphyte, W. gigantea, montrent également des similarités de structures comme l'absence de fibres extra-vasculaires et un parenchyme moins développé. La similitude des caractères chez des espèces provenant de différents habitats peut refléter soit les conditions microclimatiques sous lesquelles ces espèces se développent, ou encore des caractéristiques génétiques fixées

Anatomical and ultrastructural analyses of in vitro organogenesis from root explants of commercial passion fruit (Passiflora edulis Sims)

This study aimed to characterize the anatomical events and ultrastructural aspects of direct and indirect in vitro organogenesis in Passiflora edulis. Root explants were cultured on induction medium, supplemented with 4.44 mu M 6-benzyladenine. Roots at different stages of development were collected and processed for observation by light microscopy and scanning and transmission electron microscopy. Patterns of direct and indirect regeneration were observed in the explants. During direct organogenesis, the organogenic buds and nodules, formed from meristemoids, originated from the pericycle regions distant from the cut surface. Completely differentiated buds were observed after 20 days of culture. During indirect organogenesis, bud formation occurred via meristemoids at the periphery of the calli, which differentiated from the cortical region of the initial explant. Regardless of the regeneration pattern, the meristemoids had similar ultrastructural characteristics; however, differences were reported in the nuclear shape of the cells of the meristemoids formed directly and indirectly. This study provides important information for enhancing the understanding and characterization of the organogenic process in non-meristematic explants and provides information on the use of roots as explants in genetic transformation protocols for this important tropical species.CAPES (Brasilia, DF)CAPES (Brasilia, DF)CNPq (Brasilia, DF)CNPq (Brasilia, DF)FAPEMIG (Belo Horizonte)FAPEMIG (Belo Horizonte