Involvement of nitrate reductase in nitric oxide generation and in the induction of acclimation responses to phosphorus restriction in soybean plants.

Nitrate reductase (NR) is an essential enzyme because of its role in nitrogen metabolism and in key signaling events through the generation of the reactive nitrogen species, nitric oxide (NO). In this work, we evaluated changes in endogenous NO levels during the onset of P-restriction in soybean plants (Glycine max), focusing on the possible pathways involved in its generation, namely NR and NO synthase like activity, NOS, and the subsequent role of NR during low P-acclimation. During the first 96h of P-starvation NO levels increased in the leaves.

An Update on Nitric Oxide Production and Role Under Phosphorus Scarcity in Plants.

Phosphate (P) is characterized by its low availability and restricted mobility in soils, and also by a high redistribution capacity inside plants. In order to maintain P homeostasis in nutrient restricted conditions, plants have developed mechanisms which enable P acquisition from the soil solution, and an efficient reutilization of P already present in plant cells. Nitric oxide (NO) is a bioactive molecule with a plethora of functions in plants.

Nitric oxide and plant mineral nutrition: current knowledge.

Plants under conditions of essential mineral deficiency trigger signaling mechanisms that involve common components. Among these components, nitric oxide (NO) has been identified as a key participant in responses to changes in nutrient availability. Usually, nutrient imbalances affect the levels of NO in specific plant tissues, via modification of its rate of synthesis or degradation.

Key acclimation responses to phosphorus deficiency in maize plants are influenced by exogenous nitric oxide.

Improving phosphorus (P) acquisition and utilization in crops is of great importance in order to achieve a good plant nutritional state and maximize biomass production while minimizing the addition of fertilizers, and the concomitant risk of eutrophication. This study explores to which extent key processes involved in P-acquisition, and other acclimation mechanisms to low P supply in maize (Zea mays L.) plants, are affected by the addition of a nitric oxide (NO) donor (S-nitrosoglutathione, GSNO).

Measurement of Nitric Oxide (NO) Generation Rate by Chloroplasts Employing Electron Spin Resonance (ESR).

Chloroplasts are among the more active organelles involved in free energy transduction in plants (photophosphorylation). Nitric oxide (NO) generation by soybean (Glycine max, var ADM 4800) chloroplasts was measured as an endogenous product assessed by electron paramagnetic resonance (ESR) spin-trapping technique. ESR spectroscopy is a methodology employed to detect species with unpaired electrons (paramagnetic).

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

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).

Plant Survival in a Changing Environment: The Role of Nitric Oxide in Plant Responses to Abiotic Stress.

Nitric oxide in plants may originate endogenously or come from surrounding atmosphere and soil. Interestingly, this gaseous free radical is far from having a constant level and varies greatly among tissues depending on a given plant's ontogeny and environmental fluctuations. Proper plant growth, vegetative development, and reproduction require the integration of plant hormonal activity with the antioxidant network, as well as the maintenance of concentration of reactive oxygen and nitrogen species within a narrow range.

Chloroplast functionality has a positive effect on nitric oxide level in soybean cotyledons.

The subcellular localization of NO generation in soybean cotyledons, and the relationship between NO synthesis and in vivo chloroplast performance were studied. Employing the NO probe 4-aminomethyl-2',7'-difluorofluorescein diacetate (DAF-FM DA) and fluorescence microscopy, a strongly punctuated fluorescence was detected in mesophyll cells. The co-localization of DAF-FM and chlorophyll fluorescence, in confocal laser microscopy images, indicated the presence of NO in the chloroplasts.

Soybean ferritin: isolation, characterization, and free radical generation.

The main aim of this work was to assess the multi-task role of ferritin (Ft) in the oxidative metabolism of soybean (Glycine max). Soybean seeds incubated for 24 h yielded 41 ± 5 μg Ft/g fresh weight. The rate of in vitro incorporation of iron (Fe) into Ft was tested by supplementing the reaction medium with physiological Fe chelators.

Labile iron pool and ferritin content in developing rat brain gamma-irradiated in utero.

This study was aimed to assess the content of total Fe, Ferritin (Ft) and labile Fe pool (LIP) in developing rat brain exposed in utero to 1 Gy of gamma-irradiation. A significant increase (2.3-fold) in the total Fe content of the fetal rat brain irradiated in utero was observed from 1 to 4h post-irradiation, as compared to the content in non-irradiated brain.

Mitochondrial ferritin in animals and plants.

Ferritins play a role in preventing Fe toxicity because of their ability to sequester several thousand Fe atoms in their central cavity in a soluble, non-toxic bioavailable form. The identification of ferritin in mitochondria, an organelle with a constant generation of O2(-) as a by-product of the electron transfer, and the presence of a mitochondrial nitric oxide synthase activity opened up brand new metabolic interactions to be analyzed. In spite of cytosolic ferritins in mammals being ubiquitous, mitochondrial ferritin (mtF) expression is restricted to the testis, neuronal cells, islets of Langerhans, and as recently described to mice normal retinas.