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2. The stay-green phenotype of TaNAM-RNAi wheat plants is associated with maintenance of chloroplast structure and high enzymatic antioxidant activity

Author

Checovich, Mariana L, Galatro, Andrea, Moriconi, Jorge I, Simontacchi, Marcela, Dubcovsky, Jorge, and Santa-María, Guillermo E

Subjects
Plant Biology, Biological Sciences, Biotechnology, Genetics, Antioxidants, Carbohydrates, Chlorophyll, Chloroplasts, Electrophoresis, Polyacrylamide Gel, Iron, Oxidative Stress, Phenotype, Photosystem II Protein Complex, Plant Leaves, Plant Proteins, RNA Interference, Solubility, Sulfhydryl Compounds, Transcription Factors, Triticum, Chloroplast, NAM, Senescence, Stay-green, Triticum aestivum, Wheat, Soil Sciences, Plant Biology & Botany, Plant biology
Abstract

TaNAM transcription factors play an important role in controlling senescence, which in turn, influences the delivery of nitrogen, iron and other elements to the grain of wheat (Triticum aestivum) plants, thus contributing to grain nutritional value. While lack or diminished expression of TaNAMs determines a stay-green phenotype, the precise effect of these factors on chloroplast structure has not been studied. In this work we focused on the events undergone by chloroplasts in two wheat lines having either control or diminished TaNAM expression due to RNA interference (RNAi). It was found that in RNAi plants maintenance of chlorophyll levels and maximal photochemical efficiency of photosystem II were associated with lack of chloroplast dismantling. Flow cytometer studies and electron microscope analysis showed that RNAi plants conserved organelle ultrastructure and complexity. It was also found that senescence in control plants was accompanied by a low leaf enzymatic antioxidant activity. Lack of chloroplast dismantling in RNAi plants was associated with maintenance of protein and iron concentration in the flag leaf, the opposite being observed in control plants. These data provide a structural basis for the observation that down regulation of TaNAMs confers a functional stay-green phenotype and indicate that the low export of iron and nitrogen from the flag leaf of these plants is concomitant, within the developmental window studied, with lack of chloroplast degradation and high enzymatic antioxidant activity.

Published
2016

14. Efectos del uso de un biopreparado a base de ortigas sobre el crecimiento de plantas de lechuga

Author

Chimento, Lucía Beatriz, Simontacchi, Marcela, and Maydup, María Luján

Subjects
Lechuga, Biopreparado, Ortiga, Ciencias Agrarias
Abstract

En el Cinturón Hortícola Platense la producción de hortalizas bajo cubierta provoca un alto impacto ambiental, entre otros factores, por el gran uso de pesticidas que afectan la salud de los productores y consumidores. En el año 2015 la lechuga fue identificada como la hortaliza con mayor presencia de agroquímicos, que superaba los niveles permitidos. Los biopreparados surgen como alternativa para, mediante la promoción del crecimiento vegetal, mantener o aumentar la producción permitiendo reducir y/o eliminar el uso de agroquímicos sin perjuicios en los rendimientos. El objetivo de este trabajo fue evaluar el efecto del purín de ortiga (Urtica dioica L.) sobre el crecimiento de plantas de lechuga (Lactuca sativa L. var. capitata) bajo condiciones controladas en cámara de cultivo e investigar sus posibles mecanismos de acción., Facultad de Ciencias Agrarias y Forestales

Published
2019

15. Efecto de un fermentado vegetal de ortiga sobre el crecimiento de lechuga

Author

Oliver, Mateo, Cavigioli, Juan Pedro, Marasas, Mariana Edith, Simontacchi, Marcela, and Maydup, María Luján

Subjects
agroecologia, Lechuga, Ciencias Agrarias, purín de ortigas
Abstract

El objetivo de este trabajo fue utilizar un biopreparado, que constituye un recurso naturalizado por los productores del Cinturón Hortícola Platense, y analizar sus efectos sobre el cultivo de lechugas en condiciones de invernáculo. El purín (fermentado aeróbico) de ortigas se recomienda como estimulador del crecimiento, para prevenir enfermedades y control de pulgones y ácaros. Sin embargo la información disponible es incompleta y falta validación acerca de la forma de preparación, dosis y frecuencia de uso., Facultad de Ciencias Agrarias y Forestales

Published
2018

19. Nitric oxide is required for root organogenesis (1)

Author

Pagnussat, Gabriela Carolina, Simontacchi, Marcela, Puntarulo, Susana, and Lamattina, Lorenzo

Subjects
Genomes -- Research, Meristem -- Research, Root-tubercles -- Research, Roots (Botany) -- Research, Biological sciences, Science and technology
Published
2002

22. Eficiencia en el uso y adquisición de fósforo en plantas cultivadas: participación del óxido nítrico

Author

Ramos Artuso, Facundo, Galatro, Andrea, and Simontacchi, Marcela

Subjects
Óxido Nítrico, Ciencias Naturales, fósforo, Ciencias Agrarias, maíz
Abstract

El óxido nítrico (NO), una molécula con propiedades fitorreguladoras que presenta acción sinérgica con algunas hormonas, participa en la regulación de numerosos procesos fisiológicos relacionados al crecimiento, desarrollo y en la respuesta al estrés. Para estudiar el efecto del déficit de P y su interacción con NO, se cultivaron plantas de maíz y soja en solución hidropónica tipo Hoagland completa, y luego de siete días se separaron en cuatro tratamientos que combinaban dotación de P (0.5 mM H3PO4) con agregado de Snitrosoglutation (100 μM GSNO) como donor de NO. En todas las plantas se evaluaron parámetros bioquímicos: acumulación de P en tejidos, generación endógena de NO, presencia de antocianinas y concentración de clorofila; morfológicos: peso, longitud y área de distintos órganos, y fisiológicos: fluorescencia de clorofila y transpiración., Facultad de Ciencias Agrarias y Forestales

Published
2015

23. Efecto del óxido nítrico exógeno sobre el crecimiento de plantas de trigo durante la restricción de fosfato

Author

Ungaro Korn, Sara, Recatume Aquino, Gustavo Hernán, Simontacchi, Marcela, and Buet, Agustina

Subjects
Óxido Nítrico, Fósforo, Ciencias Naturales, trigo
Abstract

El objetivo de este trabajo fue evaluar el efecto del NO exógeno sobre el desempeño de plantas de trigo sometidas a restricción de P y su influencia sobre la eficiencia del uso del mismo., Facultad de Ciencias Agrarias y Forestales

Published
2015

24. Actividad fotosintética en plantas de soja expuestas a restricción de fósforo y oxido nítrico

Author

Delgado, Ignacio, Mateos, Rocío, and Simontacchi, Marcela

Subjects
Óxido Nítrico, Soja, Fósforo, Ciencias Naturales
Abstract

El fósforo (P) es un macronutriente esencial, que generalmente resulta un factor limitante para el crecimiento y la productividad de los cultivos. El P es un recurso no renovable, continuamente extraído del suelo por los cultivos y que presenta un ciclo sedimentario en la naturaleza. El óxido nítrico ha sido descripto como un regulador de numerosos procesos fisiológicos en los seres vivos, con funciones citoprotectoras sobre el ADN vegetal, lípidos, proteínas y clorofila, así como efectos retardantes de la senescencia [2]. En este trabajo el efecto de S-nitrosoglutatión (GSNO), como dador de óxido nítrico, fue evaluado en relación a la senescencia foliar y la distribución de P en plantas de soja expuestas a deficiencia severa de fósforo., Facultad de Ciencias Agrarias y Forestales

Published
2015

26. Endogenous ascorbate restrains apoplastic peroxidase activity during sunflower leaf development

Author

Pinedo, Marcela Lilian, Lechner, L., Creus, Cecilia Mónica, Simontacchi, Marcela Silvia, and Aguirrezábal, Luis Adolfo Nazareno

Subjects
inhibitor, Ciencias Biológicas, sunflower, leaf growth, extracellular, cell wall, Ascorbate, peroxidase, Bioquímica y Biología Molecular, CIENCIAS NATURALES Y EXACTAS
Abstract

Several apoplastic enzymes have been implicated in the control of elongation growth of plant cells. Among them, peroxidases contribute to both loosening and stiffening of the cell wall. They appear to be regulated by various mechanisms, including the action of extracellular inhibitors. To obtain evidence of the role of the enzyme–inhibitor interaction during leaf development, the intercellular washing fluids from Helianthus annuus leaves of different ages were isolated using standard methods of vacuum infiltration and centrifugation. Peroxidase activities, assessed using tetramethylbenzidine as substrate, increased during leaf development, reaching a maximum value after the leaves were fully expanded. An inhibitor, chemically characterised as ascorbate, co-localised with the enzyme in the apoplast. Moreover, there was a strong negative correlation between the action of peroxidase and the micromolar concentration of ascorbate in the apoplastic fluid. The results show that in growing leaves, the in planta ascorbate concentration is able to restrain peroxidase enzyme activity. Then, at the time of growth cessation, the loss of extracellular ascorbate relieves the inhibition on this enzyme that contributes to wall fixation. Fil: Pinedo, Marcela Lilian. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lechner, L.. Universidad Nacional de Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Creus, Cecilia Mónica. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad Nacional de Mar del Plata; Argentina Fil: Simontacchi, Marcela Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; Argentina Fil: Aguirrezábal, Luis Adolfo Nazareno. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Fisiología Vegetal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Fisiología Vegetal; Argentina

Published
2012

42. Enzymatic Sources of Nitric Oxide during Seed Germination.

Author

Lamattina, Lorenzo, Polacco, Joseph C., Simontacchi, Marcela, Jasid, Sebastián, and Puntarulo, Susana

Abstract

NO is an inorganic free radical gaseous molecule that has been shown to play an unprecedented range of roles in biological systems. Taking into account these numerous functions and the reports indicating that NO can regulate processes related to plant growth and development, endogenous sources of NO need to be clarified as well as the effect of the variations of NO levels upon the plant life cycle. We consider here the main endogenous sources of cellular NO in plant tissues, and the contribution of enzymatic sources upon seed germination. Non-enzymatic generation of NO from NO2− under conditions of low pH could be of considerable importance since significant amounts of NO2− can be found in plant tissues. However, at least under the reported experimental conditions, enzymatic activity seems to be more relevant to total NO generation, allowing a strict control of NO steady state concentration. The complexity of the overall scenario presented here shows the need for further studies into NO production and consumption pathways in germinating seeds exposed to fluctuating environmental conditions. [ABSTRACT FROM AUTHOR]

Published
2007
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49. Nitric Oxide is Involved in theAzospirillum brasilense-induced Lateral Root Formation in Tomato.

Author

Creus, Cecilia M., Graziano, Magdalena, Casanovas, Elda M., Pereyra, María A., Simontacchi, Marcela, Puntarulo, Susana, Barassi, Carlos A., and Lamattina, Lorenzo

Subjects
ROOT formation, TOMATOES, AZOSPIRILLUM, AZOTOBACTERACEAE, NITRIC oxide, NITROGEN compounds
Abstract

Azospirillumspp. is a well known plant-growth-promoting rhizobacterium.Azospirillum-inoculated plants have shown to display enhanced lateral root and root hair development. These promoting effects have been attributed mainly to the production of hormone-like substances. Nitric oxide (NO) has recently been described to act as a signal molecule in the hormonal cascade leading to root formation. However, data on the possible role of NO in free-living diazotrophs associated to plant roots, is unavailable. In this work, NO production byAzospirillum brasilenseSp245 was detected by electron paramagnetic resonance (6.4 nmol. g-1 of bacteria) and confirmed by the NO-specific fluorescent probe 4,5-diaminofluorescein diacetate (DAF-2 DA). The observed green fluorescence was significantly diminished by the addition of the specific NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO).Azospirillum-inoculated and noninoculated tomato (Lycopersicon esculentumL.) roots were incubated with DAF-2 DA and examined by epifluorescence microscopy.Azospirillum-inoculated roots displayed higher fluorescence intensity which was located mainly at the vascular tissues and subepidermal cells of roots. TheAzospirillum-mediated induction of lateral root formation (LRF) appears to be NO-dependent since it was completely blocked by treatment with cPTIO, whereas the addition of the NO donor sodium nitroprusside partially reverted the inhibitory effect of cPTIO. Overall, the results strongly support the participation of NO in theAzospirillum-promoted LRF in tomato seedlings. [ABSTRACT FROM AUTHOR]

Published
2005
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50. Nitric oxide and iron: effect of iron overload on nitric oxide production in endotoxemia

Author

Galleano, Monica, Simontacchi, Marcela, and Puntarulo, Susana

Subjects
*NITRIC oxide, *OXIDATIVE stress, *CELLS, *LIVER
Abstract

The amount of iron within the cell is carefully regulated in order to provide an adequate level of micronutrient while preventing its accumulation and toxicity. Iron excess is believed to generate oxidative stress, understood as an increase in the steady-state concentration of oxygen radical intermediates. Nitric oxide (NO) is an inorganic free-radical gaseous molecule which has been shown over the last decade to play an unprecedented variety of roles in biological systems. The effect of nitrogen reactive species may explain the iron sequestration pattern that characterizes macrophages under inflammatory conditions. From a patho-physiological viewpoint, further studies are required to assess the usefulness of this mechanism to minimize formation and release of free radicals in diseased tissues. However, contrary to the deleterious effects of the reactive nitrogen oxide species formed from either NO/O2 and NO/O2−, it has been pointed out that NO shows antioxidant properties. A number of studies have described the complex relationships between iron and NO, but controversy remains as to the influence and significance of iron on inflammatory NO production.To explore the initial steps of the effects triggered by LPS administration in the presence of excess iron, male Wistar rats were treated with: lipopolysaccharide from Escherichia coli (serotype 0127:B8) (LPS); iron-dextran; or iron-dextran plus LPS and liver samples were taken after 6 h. EPR spectra of NO-Hb in the venous blood were determined at 77 K. Iron-dextran administered to rats intraperitoneally resulted predominantly in iron uptake by the liver Kupffer cells and led to an increased NO level in blood in the presence of LPS. Further studies will be required to assess the complex role of the Kupffer cells on iNOS induction and NO production. [Copyright &y& Elsevier]

Published
2004
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