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Examinando Artículos, Informes y presentaciones en Congresos por Autor "Benvenuto, María Laura"
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Acceso Abierto Amorphous silica biomineralizations in species from Argentina: content, morphologies and tissue location, systematic and ecological relations(2016) Fernández Honaine, Mariana; Benvenuto, María Laura; Altamirano, Stella Maris; De Rito, Mara Victoria; Osterrieth, MargaritaSilici cation of plants is a widespread process and involves a high amount of plant fami- lies. The study of the content and distribution of amorphous silica biomineralizations in plant tissues has been approached by diverse disciplines, due to the relevance and applications that silicophytoliths have on di erent research areas. The knowledge of the plant production in a speci c area, has multiple applications from anatomical/functional, through ecological up to palaeobotanical and palaeoenvironmental. The present study aimed to compare the content, morphologies and tissue distribution of silicophytoliths in leaves of species from di erent communities of Argentina. We evaluated how silica content varied according to systematic, life cycles (perennials vs annuals), habit (herbs vs arboreals) and status (native vs exotic), and compared with results obtained by other researches. We analyzed at which level the phytolith morphologies can discriminate between plant groups, and which morphologies may be more relevant for taxonomy. Leaves from at least 3 individuals of 92 species, grouped in 26 families, representing some of the main communities of Buenos Aires, Misiones, and Tierra del Fuego provinces, were collected. Silicophytolith were extracted through a calcination technique, and silica content was measured as % dry weight. Silicophytoliths were counted and described under optical microscope following speci c literature. Data of silica content was subjected to Kruskal Wallis and Mann-Whitney tests, depending on the hypothesis eval- uated. Morphology data was subjected to Principal Component Analysis. Fifteen species do not produce silicophytoliths. The silica content ranged between 0.38% (Ranunculus api- ifolius) and 19% (Chusquea ramossisima) and varied according to systematic. However, it was possible to observe that two species of a same genera had di erent behavior (producer and not producer). At family level, the highest media content was observed in Urticaceae and the lowest in Ranunculaceae. Di erences were detected between Poaceae vs Asteraceae, Juncaceae, Rosaceae and Solanaceae (p< 0.01). Within Poaceae, Asteraceae and Cyperaceae families, no silica content di erences were detected among species. There were no statistical di erences between annuals and perennials, and natives and exotics (except within Poaceae family), contrary to what it was reported previously by other researchers. Leaf content in herbs was higher than in trees and shrubs (p< 0.01); however, the families with higher silica accumulation are mostly herbaceous (grasses, sedges). The main silici ed tissue is epidermis, but also xylem and parenchyma became silici ed. PCA showed that it is possible to di er- entiate some families based on their phytolith assemblages. Poaceae (short cell phytoliths), Cyperaceae (cone shaped phytoliths), Urticaceae, Moraceae and Cannabaceae (cystoliths) are clearly di erentiated from other groups. The redundancy of some morphologies such as tabular polygonal (derived from epidermis) and cylindrical sulcate xylem, makes di cult the discrimination of some groups. Finally, a detailed morphometric study will probably allow some additional di erentiation, also within the groups already di erentiated. However, be- sides the diagnostic character of the phytolith morphologies of a speci c taxa, it is relevant to increase our knowledge about the distribution of the silici cation process among plants, not only for palaeobotanical but also for anatomical, physiological and ecological purposes. - Artículo
Embargado Calcium oxalate crystal production and density at different phenological stages of soybean plants (Glycine max L.) from the southeast of the Pampean Plain, Argentina(German Society for Plant Sciences and the Royal Botanical Society of the Netherlands, 2016) Borrelli, Natalia L.; Benvenuto, María Laura; Osterrieth, Margarita• Glycine max L. (soybean) is one of the major crops of the world. Although the process of biomineralisation has been reported in some organs of soybean, we now report the description and quantification of calcium oxalate crystals in vegetative and reproductive organs of soybean during its life cycle, as they act as an important source of calcium to the soil, once the harvesting is finished. • Through diaphanisation, cross-sectioning, optical and scanning electron microscopy analysis of the organs, morphology, size and location of the crystals were identified. In addition, crystal density (n crystals mm 2) and the input of crystals to soil (n crystals ha 1) were calculated. • Soybean produced prismatic calcium oxalate crystals in vegetative and reproductive organs, generally associated with vascular bundles, resulting in a potencial transfer to the soil of 81.4 x 107 crystals ha 1 throughout its life cycle. Pods were the organs with higher calcium oxalate crystal production (1112.7 384.6 crystals mm 2), but with the smaller size (12.3 2.1 lm long). However, cotyledons were the organs that produce the larger crystals (21.3 3.5 lm long), but in lesser amounts (150.9 64.4 crystals mm 2). In leaves, although crystal size did not differ from vegetative to reproductive stage (14.5 4.2 and 14.5 4 lm in length, respectively), the crystal density increased (293.2 and 409 crystals mm 2, respectively). • These results will contribute to knowledge of the amount of calcium oxalate crystals involved in the process of Ca recycling through cultivated vegetation in fields from humid plains at medium latitudes, which therefore have biological, botanical, biogeochemical and pedological relevance. - Resumen
Acceso Abierto Calcium oxalate crystal production in different plant communities of the Pampean Plain: a comparative analysis.(2016) Fernández Honaine, Mariana; Altamirano, Stella Maris; Borrelli, Natalia L.; Benvenuto, María Laura; Osterrieth, MargaritaCalcium oxalate crystals (COC) are the most prevalent and widely distributed mineral de-posits throughout the families of higher plants. COC were analyzed in vegetative organs andfruits of 13 species from dierent plant communities of the Pampean Plain: forests (Acacia melanoxylon, Celtis ehrenbergiana, Eucalyptus globulus), agroecosystems (Glycine max), andwetlands (Alternanthera philoxeroides, Bidens laevis, Hydrocotyle bonariensis, Ludwigia pe-ploides, Mikania parodii, Polygonum hydropiperoides, Ranunculus apiifolius, Rumex crispusand Typha latifolia). Organs were placed in an ultrasound bath and washed with distilled wa-ter to remove possible mineral contaminants. Afterwards, diaphanization, clearing of tissues with 50% sodium hypochlorite and cross sectioning were realized. The material was mounted with gelatin-glycerin and COC were identied and described with optical, polarization and scanning electron microscopes. Crystal density was calculated and the composition of the crystals was analyzed by X-ray dispersive spectroscopy (EDS). Statistical analyses (Kruskal-Wallis test and Principal Component Analysis) were made in order to compare COC size and production between communities, species and organs. Druses were observed in C. ehrenber-giana, E. globulus, A. philoxeroides, H. bonariensis, L. peploides, P. hydropiperoides, and R.crispus. Raphide bundles were present in L. peploides and T. latifolia; and prismatic crystalsin A. melanoxylon, E. globulus, H. bonariensis, L. peploides and R. crispus. Calcicationmainly occurred in parenchymatous tissue. No COC were observed in B. laevis, M. parodiiand R. apiifolius. A single crystal morphology was observed per organ, except in leaves ofL. peploides and E. globulus, which present both druses and raphides, or druses and prismatic crystals, respectively. In fruits, only prismatic crystals were observed independently of the morphology produced in the vegetative organs. The species analyzed had signicant differences in the size of the COC (H: 443.5, p< 0.001). Particularly, some aquatic species(A. philoxeroides, L. peploides, P. hydropiperoides and R. crispus), given the great size oftheir druses (36-58m), could not be differentiated among them (p> 0.05). Consideringeach species, the fruits had smaller COC (5-11m) than the vegetative organs (14-210m,p< 0.001). The COC density was signicantly dierent between communities, species andorgans, and allowed to distinguish the community and the organs with greater productionof COC. Thus, the tree species were grouped together with the fruits of the species analyzedgiven their greater COC density: 9167-28308 and 1112-18531 crystals/mm2, respectively. Inside this group, C. ehrenbergiana and E. globulus have more anity because they produce druses, unlike A. melanoxylon and the fruits analyzed that produce prismatic crystals. It was not possible to discriminate between the aquatic community (7-250 crystals/mm2) and thecrop (340 crystals/mm2). The description and quantification of COC allowed to distinguish among different plant communities, species and organs. The fruits showed the smallest size and the highest density of crystals. This particular pattern ensures the normal growth and development of the embryos, since crystals act as a calcium source, prevent damage frominsects and allow reproductive success of the species. - Artículo
Embargado Early silicification of leaves and roots of seedlings of a panicoid grass grown under different conditions: anatomical relation and structural role(German Botanical Society and The Royal Botanical Society of the Netherlands, 2016) Fernández Honaine, Mariana; Benvenuto, María Laura; Borrelli, Natalia L.; Osterrieth, Margarita• Grasses accumulate high amounts of silica deposits in tissues of all their organs, especiallyat mature stage. However, when and under which conditions do grass seedlings begin to produce these silica deposits and their relation with anatomy and developmentis little known. Here we investigated the silicification process in the first leavesand roots of seedlings of Bothriochloa laguroides grown in different substrate and Sitreatments. • The distribution and content of silica deposits in the organs of the seedlings grownunder different conditions were analyzed through staining techniques and SEM-EDAXanalyses. • Leaf silica deposits were accumulated 3–4 days after the first leaf emergence, alsounder low silica solution (0.17–0.2 mM). Their location was mainly restricted to shortcostal cells from basal sectors, and scarcely in trichomes and xylem at tips. Silica contentin leaves increased with the age of the seedlings. Roots presented dome-shaped silica aggregates, between 4–12 lm of diameter, located in the inner tangential wall ofendodermal cells and similar to those produced at maturity. • Silicification begins early in the first photosynthetic leaf, and silica distribution isopposite to that found in mature plants, mainly restricted to basal sectors, probablyacting as a reinforcing element. The fast incorporation of solid amorphous silica inleaves and roots, may be useful for farm applications in species that are Si-fertilized - Resumen
Acceso Abierto Root silicification of grasses and crops from Pampean region and its relevance on silica and silicophytolith content of soils(2016) Fernández Honaine, Mariana; Paolicchi, Micaela; Osterrieth, Margarita; Benvenuto, María LauraRoot tissues of grasses and dicots can accumulate amorphous silica. Particularly in Poaceae family, silica can be restricted to the endodermis, spread throughout all tissues or deposited into intercellular spaces. The aim of the present study were 1) to analyze the silica content in typical grasses and crops (soybean, maize, wheat) from Pampean region, Argentina; 2) to evaluate the potential input of silica and silicophytoliths from roots to soils in natural and cultivated areas. Roots from eight typical pampean grasses and three crops were collected from eld. Also, soil samples, including the roots developed within them, were collected every 10 cm along the pro les from natural and cultivated areas. They were dried and weighted, and the relative contribution of roots to total weight was calculated. Root silicophytoliths were extracted following a calcination technique and the content was calcu- lated as percentage of dry weight. Silicophytolith morphologies were described under light microscope, according previous literature. Silicophytolith content ranged between 4-11% in pampean grasses and between 0.8-4.20% in crops. Bothriochloa laguroides and Sorghastrum pellitum produce silica aggregates in endodermal walls; while the rest of the grasses produce silici cations of endodermal walls and xylem. In crops, silica is deposited in xylem, endoder- mal cells and epidermal cells. In soils, the abundance of roots was higher at the rst 10 cm. In this section the roots represented the 0.39% of the weight of natural soils and 0.03% of cultivated soils. Towards the base to the pro les the values ranged between 0.0013-0.023% and 0.002-0.001%, in natural and cultivated soils, respectively. Considering a 15% (mean value) of silica content of roots obtained from soils, the total silicophytolith input from roots to soils was 0.0585 gr per 100 gr of soil (at rst 10 cm) and between 0.000195-0.00345 gr per 100 gr of soil (10-60 cm) in the natural area. Instead, in crop area, where silica in roots was 11%, the mean value of silica input was 0.0033 gr per 100 gr of soil ( rst 10cm) and 0.00011-0.00022 gr per 100 gr of soil (10-60cm). The main morphologies found in soil roots were silici ed xylem and elongate phytoliths, similar to those found in roots from Pooideae grasses and crops. The results obtained in this study revealed that 1) silicophytolith produc- tion in roots from pampean grasses and crops is abundant; 2) the morphologies found arecoincident with previous studies in relation to Poaceae; 3) the input of silica and silicophy- toliths from roots to soils may be more relevant in natural than in cultivated areas, due to the higher development of roots but also due to the higher production of silicophytoliths in native grasses. Since the root silicophytolith morphologies seem to be more labile than the morphologies produced by other grass organs, it may be possible that they have a strongest influence on silica cycle in soils, due to a higher/faster dissolution rate; and also it may contribute to preservation of soil aggregates, due to the role that silica has on soil structure. - Resumen
Acceso Abierto Silicophytoliths and silicon studies by field assays in mollic epipedons of the southeastern Pampean Plains, Argentina(2016) Osterrieth, Margarita; Frayssinet, Celia; Benvenuto, María Laura; Borrelli, Natalia L.; Heiland, Patricio; De Rito, Mara Victoria; Fernández Honaine, MarianaSilicon is the second most abundant element in the earth's crust. It is essential for the normal development and growth of plants, and plays a key role in the physical, chemical and biological soil properties. Silicon is important in the formation of inorganic matrix and supporting structures, which in turn condition the availability and mobilization of basic elements,such as C, 0 , P, Al, and trace elements. Amorphous silica biomineralizations (silicophytoliths) constitute a significant source of silicon to the soil-plant-atmosphere system, as they dissolve faster than silicate minerals. However, their role in agronomic aspects related to the loss of physical, chemical and biological fertility is still poorly documented. Research on the importance of silicon nutrition in order to promote plant growth has been reported in many countries, but not in Argentina. Given the negative effects that the intense agricultural activity has been causing on soils of the Pampean Plain, this work aimed at evaluating the silicophytoliths and silicon contribution in natural and experimental soils sowed with two varieties of wheat (Aviso and Baguette), and with the application of solid (Silfix) or liquid (Quicksoil) silicon fertilizers . The content of silicophytoliths (% dry weight) in wheat was determined by calcination, and the content of SiO2 in soil solutions was determined through UV-Vis spectrophotometry by the silicomolybdate method. Wheat plants ( Triticum aestivum) produced 27 Kg silicophytoliths.ha-1 in the vegetative stage, and 738 Kg silicophytoliths.ha-1 in the maturity stage. Media values of silicon in soil solutions varied from 1100 μmol/L in natural soils, to 722 μmol /L in plots with solid silicon fertilizer and 635 μmol/L in plots with liquid silicon fertilizer. These results, showing a substantial Si content decrease in cultivated soils, are important in order to advance into the knowledge of inputs and losses of silicon in agro-ecosystems. Specially, given the increase of the production of some crops that are not commonly producers of silicophytoliths/ silicon (like soybean) in the Pampean Plain of Argentina. The Argentinian perspectives on agriculture application of silicon fertilizers and silicon enhancement of crops quality were also discussed. This work was supported by the Agencia Nacional de Promoci6n Cientifica y Tecnol6gica, Ministerio de Ciencia y Tecnica (PICT 1583-2013) and Universidad Nacional de Mar del Plata (EXA 741 / 15). - Resumen
Acceso Abierto Silicophytoliths and taphonomy in Cenozoic pedostratigraphic sequences of the Pampean Plain, Argentina(2016) Osterrieth, Margarita; Borrelli, Natalia L.; Benvenuto, María Laura; Fernández Honaine, Mariana; Frayssinet, Celia; Altamirano, Stella Maris; De Rito, Mara Victoria; Donna, Roberto; Paolicchi, Micaela; Álvarez, María FernandaGrasslands and savannas occupy one forth of the total surface of South America continent, and within it, the Pampean plain region, located in the central area of eastern Argentina, covers an area of 1,200,000 km2. The dominant soils are Mollisolls generally deep, developed from well-drained loessic parental material and characterized by a silty-loam texture. Pampean Plains is one of the most fertile regions of the world. Intense agricultural activities are carried out there and this, in turn, has strongly modified the native plant communities, especially grasslands. Depending on the environmental and pedological conditions, silicophytoliths are affected by diverse taphonomical processes, both in natural and anthropic environments. They can be preserved, dissolved or fragmented, and also be transported by different agents (wind, water, animals and people). Other taphonomical aspects also important to evaluate are the methodologies used in silicophytolith studies, from soil sampling to studies at a submicroscopic level. There are several current methodologies and the work is essentially done at a very detailed resolution level, which could lead to interpretation errors if the environmental or paleoenvironmental context of the study material is unknown or not clearly stated. The study area is located in regional geomorphological units from Pampean Plain, Argentina, and integrated profiles representative of typical pedoestratigraphic sequences were analyzed. Silicophytoliths were analyzed as part of the whole mineralogy of the soil samples and morphologies were described under optical and scanning electron microscopes. The results show high amounts of silicophytoliths which have been affected by various physical and chemical alteration and/or by taphonomic processes of different types and degrees of intensity. The percentage and number of silicophytoliths per gram of soil vary. In superficial horizons (O, A), the percentage ranged between 10-65%, with 11.000.000-30.000.000 phytoliths per gram of soil (n/g.s). In subsuperficial horizons (AC, B, BC) between 2-6% and 1.000.000-5.000.000 silicophytoliths n/g.s were observed. The percentage of silicophytoliths in loessic parent material (C) ranges between 0.4-2%, with 500.000-2.000.000 n/g.s. In paleosols, percentages range between 1-8%, and the number of silicophytoliths per gram of soils were 1.500.000-8.000.000. Silica and silicophytolith biomass content per ha of soil varied according C biomass, in the pedostratigraphic Cenozoic sequences from Pampean plains. Our data show that the content of silicophytoliths decreases between 50 and 95% from superficial to subsuperficial soil horizons due to pedological processes. The comprehension of the physico-chemical degradation and transference processes within silicophytolith-plant-soil-environment system is essential in order to evaluate the role of taphonomical processes in the biogeochemical cycle of silicon. Finally, it is proposed that the displacement of native grasslands may be bio-physico-chemically balanced by the introduction of crops, in relation to the silicon cycle, since they are also important silicophytolith producers in the SE Pampean agroecosystems. Acknowledgments: This work was supported by PICT 1583/2013 AGENCIA and EXA 741/15-UNMDP.