Populus deltoides clones are widely planted in Argentina, in a region called “Paraná River Delta”. In this site, Pycnoporus sanguineus and Ganoderma lucidum (Aphyllophorales) cause white-rot decay in both living and felled poplar trees. The purpose of this work was to estimate, through laboratory decay tests, the ability of both fungi to degrade poplar wood and to describe the patterns of decay using light and scanning electron microscopy. Two exposure times were analyzed: 75 and 150 days. The percent weight loss produced by both fungal strains was similar for both exposure periods (c. 50–60% of wood mass) but microscopic observations showed there were different patterns of decay. Samples inoculated with P. sanguineus showed a selective delignification, whereas those inoculated with G. lucidum exhibited a combination of simultaneous decay and selective delignification. Separation among cells was the main diagnostic feature for selective decay. By contrast, the presence of erosion troughs, cell wall thinning, bore holes, rounded pit erosion and erosion channels were diagnostic for the simultaneous type of decay.
Diversity of ferns and lycophytes from Reserva Natural Punta Lara, Buenos Aires, Argentina. Punta Lara Natural Reserve shelters the relict of the Southernmost riparian forest in the world, where the flora is threatened by the anthropic expansion and by the introduction of exotic species. In this area the ferns and lycophytes grow in particular environments as marshland, grassland and marginal forest. The aim of this work was to evaluate the diversity of ferns and lycophytes that inhabit in Punta Lara Natural Reserve. Field trips were conducted from 2006 to 2009 and local herbaria and specific bibliography were also revised. As a result of our study twenty four taxa of ferns and lycophytes were recognized. Their habit was mainly terrestrial (70%), fewer aquatic (17%) and epiphytic (13%). Five native taxa were scarcely recorded whereas two native species previously documented were not found. We assume that the main threats on ferns and lycophytes populations in Punta Lara Reserve are: removal for comercialization, invasion by exotic species and climatic fluctuations (drought periods). Keys for taxa identification are given and strategies for the conservation of threatened taxa are proposed. Rev. Biol. Trop. 59 (3): 1037-1046. Epub 2011 September 01.
Summary:Anogramma chaerophylla belongs to a fern genus with annual sporophytes and potentially perennating gametophytes. In the studied area, Natural Reserve Punta Lara, the plants grow stressed mainly by pollution and the invasion of exotic species. As a part of a project on conservation of ferns inhabiting Buenos Aires province, the objectives of this work were to evaluate in Anogramma chaerophylla the conditions for in-vitro spore germination and to analyse the different stages of its reproductive cycle. Spores were sterilized in an aqueous solution 10 % of NaCIO during different times and then sown in Petri dishes with Murashige & Skoog medium, without the addition of sucrose. The dishes were kept under laboratory conditions, at 12 h light/ darkness photoperiod and a temperature of 22 (± 2) °C. After two weeks, the percentage of germination was 80%. The spore germination pattern corresponds to the Vittaria type and the prothallus development was Ceratopteris type. Gametangia developed first in the bended thalloid region of the prothallus and then bisexual tubercles originated near this zone. The sporophytes developed only in association with the tubercles. During culture in plastic pots the sporophytes gave origin to a second generation of prothalli. Our preliminary findings demonstrate that the in vitro culture technique is suitable for A. chaerophylla propagation as a strategy for ex-situ conservation.Key words: Anogramma chaerophylla, micropropagation, gametophyte, tubercle, ex-situ conservation Resumen: El cultivo in vitro de esporas y los aspectos reproductivos del helecho anual Anogramma chaerophylla (Pteridaceae). Anogramma chaerophylla pertenece a un género de helechos con esporofitos anuales y gametofitos potencialmente perennes. En el área de estudio, la Reserva Natural Punta Lara, la vegetación crece bajo estrés debido principalmente a la contaminación y la invasión de especies exóticas. Como parte de un proyecto de conservación de helechos que habitan en la provincia de Buenos Aires, los objetivos del trabajo fueron evaluar en Anogramma chaerophylla las condiciones para la germinación de esporas in-vitro y analizar las distintas etapas de su ciclo reproductivo. Las esporas fueron desinfectadas en solución 10 % de NaCIO durante distintos tiempos y sembradas luego en medio de cultivo Murashige -Skoog, sin agregado de sacarosa. Las cápsulas se incubaron con un fotoperíodo de 12 h luz/oscuridad y una temperatura de 22 (± 2) °C. A las dos semanas germinaron el 80% de las esporas. El patrón de germinación fue tipo Vittaria y el desarrollo del protalo tipo Ceratopteris. Los gametangios aparecieron primero en la región engrosada del protalo donde posteriormente se originaron los tubérculos bisexuales. Los esporofitos se desarrollaron solo en asociación con los tubérculos. Durante su cultivo en macetas, éstos dieron origen a una segunda generación de protalos. Nuestros resultados demuestran que la técnica de cultivo in vitro es apropiada para la propagación de Anogramma chaerophylla y como estrategia para...
Sexual morphogenesis phase of the epiphytic ferns Microgramma mortoniana and Pleopeltis macrocarpa (Polypodiaceae) from Punta Lara Natural Reserve, Buenos Aires, Argentina. The Punta Lara Natural Reserve is located on the riverside of the La Plata River in the province of Buenos Aires, Argentina. It is the Southernmost relict in the world of subtropical riparian forest. The epiphytic ferns studied in this work belong to the Polypodiaceae family: Microgramma mortoniana and Pleopeltis macrocarpa. Plant communities are subject to high levels of anthropization and introduction of exotic species. The goals of this work are to provide information on the morphogenesis of epiphytic gametophytes and to extend knowledge of their life cycles, contributing to their conservation. Sowing was carried out in Dyer medium. In both species the spores are monolete, ellipsoidal, yellowish and with verrucate sculpture. The equatorial diameter is 60-61 μm, the polar diameter is 39-42 μm. The germination is the Vittaria type; in M. mortoniana occurs at 20 days, while in P. macrocarpa occurs at six days. The filaments are uniseriate of 3-6 cells in length. The gametophyte development is Drynaria type. The cordated form is given after 40 days. In M. mortoniana, buds originated after 40 days. In P. macrocarpa, after 120 days, clathrate trichomes scale-like appear mainly on the margins of the gametophyte. The gametangia are typical of leptosporangiate ferns. The sporophyte of M. mortoniana emerged after 120 days and that of P. macrocarpa arose after 500 days, its blades are simple, spatulate and unicellular and multicellular branching hairs were observed. The germination pattern, gametophyte development, the presence of a lipid globule in the prothalic cell and the formation of unicellular capitated hairs are relevant characters that could be considered for systematic group. The delay in the formation of sporophytes through sexual reproduction, allows us to infer that the success of their establishment in situ would be given by the vegetative reproduction through creeping rhizomes and buds of gametophytes. Rev. Biol. Trop. 66(3): 1078-1089. Epub 2018 September 01.
The number of species recognized loi this genus varies ,|, i ,,m authors from one to four. The goal of this work was to provide a systematic revision of the genus Salpichlaena in order to contribute to the knowledge of the fern biodiversity in America. For this purpose morphological, anatomical and palynological characters were analyzed in material from the geographical distribution of Salpichlaena. Herbarium spn imens were Invited according to the standard techniques for LM and SEM studies. The type specimens and the original descriptions were consulted to determine the applications of names. Two species are recognized, S. volubilis (Kaulf.) }. Sm. and S. hookeriana (Kuntze) Alston. Salpichlaena hookeriana differs from S. volubilis by pronounced foliar dimorphism (the fertile pinnules are much reduced), the presence of foliar buds on sterile basal pinnules, ovate costular scales and the presence of glandular hairs on the abaxial surface of the costa. The spores are monolete in both taxa, with rugulategranulate perispore and superficial spherules. Salpichlaena volubilis is widely distributed in Central and South America, from Guatemala and Caribbean Islands, up to southern Brazil and Bolivia, across a wide altitudinal range of 200 to 1900 Colombia. Venezuelan Guyana, Suriname, British Guia altitudes up to 800 m. The diagnostic characters, illu species are given.
Schinopsis haenkeana is a native tree to the Chaco Serrano Forests in Argentina. The white-rot fungus Phellinus chaquensis degrades its wood, causing a whiterot type of decay. The objective of this study was to investigate the structural alterations caused by P. chaquensis in S. hankeana decayed naturally and in vitro. Sound living branches with decay and basidiocarps of P. chaquensis were sampled from the field and in vitro decay tests were performed according to the ASTM D-2017-81 standard method. Naturally decayed branches exhibited an innermost discolored zone with white-rot decay and an outer yellowish-white portion of sound sapwood. Using LM and SEM, degraded tissue displayed diagnostic characters of selective delignification and simultaneous decay. Findings indicate that P. chaquensis causes a mottled pattern of decay (selective delignification plus simultaneous decay) in S. haenkeana wood. Other features such as accumulation of extractives, profuse deposition of crystals and tyloses, typical ofSchinopsis spp. heartwood, were additionally observed. In laboratory degraded material, signs of selective delignification and incipient stages of simultaneous decay were noticeable only microscopically. Chemical analysis revealed an oxidative alteration of aromatic moieties in naturally decayed samples which might be related to the accumulation of phenols as a response to fungal attack when compared to sound samples. Naturally degraded sapwood exhibits anatomical and chemical modifications that indicate the development of discolored wood derived from the host-pathogen interaction.
Introducción y objetivos: Las características externas e internas de los pecíolos brindan información útil para los estudios taxonómicos en helechos. El objetivo de este trabajo fue analizar los caracteres diagnósticos del pecíolo en las 37 especies de Asplenium que crecen en Argentina, para contribuir a su identificación e indagar sobre su significado adaptativo.M&M: Se emplearon especímenes de herbario y material fresco. Los materiales se analizaron con microscopios estereoscópico y óptico; en el último caso las muestras fueron procesadas siguiendo las técnicas histológicas convencionales. Los caracteres analizados fueron: color, longitud, presencia de alas, tejido mecánico sub-epidérmico, líneas de aireación, banda circumendodermal (BC), forma y número de los haces vasculares y contorno del xilema.Resultados: Algunas características de los pecíolos permiten el agrupamiento de especies. Los caracteres diagnósticos son: color, presencia/ausencia de alas, número de haces vasculares, contorno de los haces, contorno del xilema y presencia/ausencia de BC.Conclusiones: Los caracteres del pecíolo por si solos no permiten la identificación de los taxa a nivel específico, si bien junto con otros contribuyen a la sistemática del género. La anatomía del pecíolo no evidencia en general relación con el hábito de estas plantas. El tipo y la disposición del tejido mecánico sub-epidérmico y la presencia de BC se asocian a especies que crecen en ambientes expuestos y secos, pero no son exclusivos de los taxa que crecen bajo estas condiciones."
The xylem in three arborescent species of Blechnum section Lomariocycas was studied in detail using SEM, TEM, FT-IR spectroscopy and sugar composition analysis. The overall structure of root and rhizome metaxylem tracheids was similar in the three species analyzed, and characterized by mostly scalariform pitting of these multifaceted cells. Pit membrane thickness and porosity varied according to the stage of tracheid maturation. Approximately rounded deposits resembling vestures were observed in the outer pit apertures of some tracheids. Under TEM, thickenings like one-sided tori appeared on the tracheid side of tracheid-to-parenchyma contact walls; some parenchyma cells showed, in addition, features of transfer cells. As the increase in stature creates new constraints in terms of biomechanical support and water transport in plants, the characteristics found in Blechnum xylem might be related to optimization of conductive efficiency and safety. Chemical analyses of roots and rhizomes of B. yungense revealed similar levels of G-type lignin deposited in the xylem cell walls. Such lignin is the most common in ferns, including other arborescent genera. Preliminary analysis of cell wall polysaccharide composition of both root and rhizome xylem, yielded cellulose, xyloglucans and xylans with low amounts of mannans and pectins. The xylem of rhizomes had higher amounts of cellulose than root xylem. Our results are discussed in the context of functional and evolutionary aspects of xylem ferns.
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