ABSTRACT
The purpose of this study was to develop a pollen preparation methodology with a high proportion of intact pollen of species for the genus Passiflora subg. Passiflora. Thus, flower buds were collected near anthesis, from the species: P. alata, P. edulis, P. foetida, P. giberti, and P. setacea, fixed in ethanol-acetic acid mixture (3:1) and treated in 10%-20% aqueous sodium hydroxide, or acetolyzed. The pollen treated with 10% sodium hydroxide resulted in an average of 96% intact pollen grains in all species, however, after acetolysis an average percentage of 98% broken pollen was observed. Data obtained in pollen measurements did not change with the new methodology. It is therefore evident that the proposed methodology for pollen preparation based on sodium hydroxide was effective, as it allowed the visualization of a significant amount of intact pollen, thus promoting morpho-palynological studies of these species.
Este estudo teve como objetivo elaborar uma metodologia, para obter preparos polínicos com alta frequência de polens íntegros de espécies representantes do gênero Passiflora subg. Passiflora. Dessa forma, botões florais foram coletados, próximo à antese, das seguintes espécies: P. alata, P. edulis, P. foetida, P. giberti e P. setacea, fixado em solução etanol-ácido acético (3:1) e tratado em solução aquosa de hidróxido de sódio (10 e 20%) ou acetolisados, independentemente. Os preparos palinológicos, quando tratados com hidróxido de sódio a 10%, evidenciaram, em todas as espécies, média de 96% de polens íntegros, em contrapartida, quando acetolisados foi observada uma percentagem média de 98% de polens rompidos. Os dados referentes a mensurações polínicas não sofreram alterações com a nova metodologia. Evidencia-se, dessa forma, que a metodologia proposta, para preparações polínicas à base de hidróxido de sódio, foi eficiente, pois promoveu a visualização de uma quantidade significativa de polens íntegros, favorecendo assim o estudo da morfologia polínica nessas espécies.
Subject(s)
Pollen , Sodium Hydroxide , Passiflora , PassifloraceaeABSTRACT
The system of Ibera lake and marshes in the Province of Corrientes, covers an area of approximately12 000km², and is considered one of the most important wetlands in Latin America. Given the wide diversity oftropical communities in this area, it is important to generate new information about the different species of this ecosystem, through pollen morphology, as lake sediments favor the pollen grains conservation. With the aim to promote future research on systematics, vegetation history and melissopalynology of this region, this study attempted to describe the pollen morphology of the well represented genus Senna. For this, we conducted 5-8 days collection trips in Southeast Ibera, on a monthly basis between 2009 and 2011. Based on the plants collected, the literature review and databases from the herbarium of the Botanical Institute of Northeast Argentina, we developed a list of species for the Province of Corrientes. For the pollen morphology, we manually took at least three flower buds per flower in the sampled sites, and for those species not sampled in the field, samples were obtained from the IBONE herbarium. Palynological material preparation was carried out by a modified tech nique of Erdtman acetolysis. The palynological descriptions considered the polar and equatorial diameter, exine thickness, openings and sculptural elements. Our results showed that Senna genus is euripalynic, composed of 3-colporate pollen grains, small to medium size, radiosymmetric, isopolar, oblates-spheroidals to prolates, subcircular field, subtriangular to triangular and long colpis. We described for the first time, the pollen morphology of 17 species of the genus Senna for this area, and recognized two groups considering endoapertures: lalongates and circular. The list of species belonging to the genus Senna presented here could be considered in restoration and recovery plans. A major constraint for the correct interpretation of the environmental changes impacts in vegetation, whether of climatic and/or anthropogenic origin, is the knowledge of pollen morphology of tropical species. A palynological database is of high value for the interpretation and determination of plant species.
El sistema de esteros y lagunas del Iberá, en la provincia de Corrientes abarcan aproximadamente 12 000km² de superficie y es considerado uno de los humedales más importantes de Latinoamérica. Dada la gran diversidad de las comunidades tropicales en esta área, es importante generar nueva información sobre las diferentes especies de este ecosistema, a través de la morfología del polen, ya que los sedimentos lacustres constituyen un medio ácido, pobre en oxígeno y favorable a la conservación de granos de polen que se depositan en su superficie. Con el objetivo de promover futuras investigaciones sobre la sistemática, historia de la vegetación y melisopalinología de esta región, el estudio trató de describir la morfología polínica del género Senna, que se halla bien representado en la zona. Se elaboró un listado de especies pertenecientes a la Provincia de Corrientes. Este listado se realizó mediante recolectas botánicas realizadas en el Sureste del Iberá, durante 5 a 8 días de cada mes entre 2009 y 2011, adicionalmente, se consultó literatura especializada y bases de datos de herbario del Instituto de Botánica del Nordeste Argentino. En cuanto al estudio morfológico del polen, se tomaron manualmente los botones florales de ejemplares en la zona de estudio. Para aquellas especies que no pudieron ser muestreadas en campo, se precisó de la toma de botones florales del herbario del IBONE. La preparación del material palinológico se llevó a cabo por la técnica modificada de acetólisis de Erdtman. Las descripciones palinológicas consideran el diámetro polar y ecuatorial, grosor de la exina, aberturas y elementos esculturales. Los resultados muestran que el género Senna es euripolínico, compuesto de granos 3-colporados pequeños a medianos, radiosimétricos, isopolares, oblatos-esferoidales a prolatos, ámbito subcircular, subtriangular a triangular; colpos largos. Aquí, se describen por primera vez para la zona, la morfología polínica de 17 especies del género Senna, del sureste del sistema Iberá, reconociéndose dos grupos teniendo en cuenta endoaperturas: lalongadas y circulares. El listado de especies pertenecientes al género Senna presentado en este trabajo debe ser considerado en las actividades de restauración y recuperación de los diferentes tipos de vegetación. Una limitación importante para la correcta interpretación del impacto de las variaciones ambientales en la vegetación, ya sean climáticas y/o antropogénicas, es el conocimiento de la morfología polínica de las especies tropicales, por lo tanto, se debe contar con una base de datos palinológica a nivel morfológico que ayude a la interpretación y determinación de especies vegetales.
Subject(s)
Pollen/ultrastructure , Senna Plant/classification , Argentina , Microscopy, Electron, Scanning , Senna Plant/ultrastructureABSTRACT
Pollen morphology of neotropical species of Podostemum (Malpighiales: Podostemaceae). Pollen morphology of neotropical species of Podostemum is described for the first time with light (LM) and scanning electronic microscopes (SEM), using pollen dehydration by critical point. Herbarium specimens under study are P. comatum, P. distichum, P. muelleri and P. rutifolium. Pollen grains are dispersed in dyads. Observed with LM, dyads range from 21 to 31μm in lengh and 12 to 18μm wide. Individual pollen grains are radially symmetrical spheroidal to subprolate, and have a tricolpate aperture. The exine is tectate, psilate, with an infratectal structure formed by simple columella under the tectum. With SEM, an abundant pollen surface coat is observed all over the pollen grains, mainly in the two grains dyad contact zone. This pollen coat would protect the grains from dehydration because the environments in which these plants grow have important water variation and pollination is not zoophilic. The shared dyad wall shows bridges that partially fusion the exines, forming calymate dyads. Some dyads bear the apertures aligned between grains and some not. The transverse condition of the aperture or aperture in "L" that occurs in the four studied species is described for the first time. It is interpreted as a trend of the genus to espiroaperture. This change in the aperture would be associated with phenology because it is a genus with very short flowering and anthesis, generally a day of anthesis in the dry season. The spiroaperture increases the chances of germination sites and would also have a harmomegata role in an environment with water changes favoring the reproductive success.Walls have a microechinate sculpture, with or without pads at the base of the microechinae. Size of ornamental processes differs, and the colpus membrane has similar ornamentation to that of the non apertural wall, but with larger processes. Individual morphology of pollen grains is similar to that described for other family genera as Apinagia and Mourera. During previous stages of anthesis, the presence of cross tetrads was observed, also a new contribution for this genus. Rev. Biol. Trop. 58 (1): 81-88. Epub 2010 March 01.
La morfología del polen de cuatro especies neotropicales del género Podostemum (Podostemaceae) se describe aquí por primera vez mediante microscopía de luz y electrónica de barrido, utilizando material deshidratado en punto crítico. Se analizaron ejemplares de P. comatum, P. distichum, P. muelleri y P. rutifolium. Los granos de polen son dispersados en díades. Se encuentra abundante cobertura polínica, principalmente en la zona de contacto entre los dos granos de la díada. En la pared compartida entre los granos se presentan puentes de ectexina que fusionan parcialmente las exinas. Los granos individuales son radialmente simétricos y tricolpados. En algunas díades las aberturas están alineadas entre los granos y en otras no. Se describe por primera vez la condición abertura transversal, que fue observada en las cuatro especies estudiadas, y que se interpreta como tendencia del género a espiroabertura. La escultura de la exina es microequinada con mamelones en la base. Los procesos ornamentales son de diferente tamaño. La membrana del colpo tiene una ornamentación similar a la pared adyacente del grano, pero los procesos tienen mayor tamaño. Se observaron tétrades decusadas en las etapas previas a la antesis, un dato hasta el momento no registrado para el género.
Subject(s)
Magnoliopsida/anatomy & histology , Pollen/anatomy & histology , Argentina , Magnoliopsida/classification , Magnoliopsida/ultrastructure , Microscopy, Electron, Scanning , Pollen/ultrastructure , Species SpecificityABSTRACT
The pollen grains collected by Melipona seminigra merrillae, Melipona compressipes manaosensis, Melipona seminigra seminigra, Frieseomelitta sp. and Scaptotrigona sp. were obtained directly from the corbiculae of the worker bees during one year. Identification of the pollen grains showed that Scaptotrigona sp. was the most generalist bee, followed by Frieseomelitta sp., which together collected more pollen taxa than the three species of Melipona. Pollen from three plant species: Miconia myrianthera, Myrcia amazonica e Tapirira guianensis -were collected by this five bee species. Regarding pollen morphology, no significant correlations were found that could indicate a preference for certain pollen grain forms, external structures or sizes of grains. All five meliponids collected pollen of several forms and sizes. It is indicative that the bees collected pollen in accordance to protoplasmic nutrients. Biochemical analyses of some pollen types carried on the corbiculae of the bees showed a high concentration of total soluble sugars, reductive sugars and starch.
Durante um ano, o pólen transportado por Melipona compressipes manaosensis, Melipona seminigra merrillae, Melipona seminigra seminigra, Frieseomelitta sp. e Scaptotrigona sp. foi coletado diretamente das corbículas das operárias. Feita a identificação dos grãos de pólen constatou-se que a abelha mais generalista foi Scaptotrigona sp., seguida de Frieseomelitta sp., as quais juntas coletaram mais tipos polínicos que as três espécies de meliponas. Duas espécies de plantas: Miconia myrianthera e Myrcia amazonica, tiveram seu pólen coletado pelas cinco espécies de meliponíneos durante o ano todo. Quanto à morfologia do pólen, não houve correlação significativa que comprovasse que as abelhas coletassem o pólen de acordo com a forma, ornamentação e o tamanho dos grãos. As cinco espécies de meliponíneos coletaram pólen de diversas formas e tamanhos. Tudo indica que as abelhas coletam o pólen de acordo com os nutrientes contidos no seu protoplasma. Análises bioquímicas de alguns tipos polínicos encontrados nas corbículas das abelhas apresentaram alto teor de açúcares solúveis totais, açúcares redutores e amido.