Dynamic compartment specific changes in glutathione and ascorbate levels in Arabidopsis plants exposed to different light intensities

Abstract

BackgroundExcess light conditions induce the generation of reactive oxygen species (ROS) directly in the chloroplasts but also cause an accumulation and production of ROS in peroxisomes, cytosol and vacuoles. Antioxidants such as ascorbate and glutathione occur in all cell compartments where they detoxify ROS. In this study compartment specific changes in antioxidant levels and related enzymes were monitored among Arabidopsis wildtype plants and ascorbate and glutathione deficient mutants (vtc2-1 and pad2-1, respectively) exposed to different light intensities (50, 150 which was considered as control condition, 300, 700 and 1,500 μmol m-2 s-1) for 4 h and 14 d.ResultsThe results revealed that wildtype plants reacted to short term exposure to excess light conditions with the accumulation of ascorbate and glutathione in chloroplasts, peroxisomes and the cytosol and an increased activity of catalase in the leaves. Long term exposure led to an accumulation of ascorbate and glutathione mainly in chloroplasts. In wildtype plants an accumulation of ascorbate and hydrogen peroxide (H2O2) could be observed in vacuoles when exposed to high light conditions. The pad2-1 mutant reacted to long term excess light exposure with an accumulation of ascorbate in peroxisomes whereas the vtc2-1 mutant reacted with an accumulation of glutathione in the chloroplasts (relative to the wildtype) and nuclei during long term high light conditions indicating an important role of these antioxidants in these cell compartments for the protection of the mutants against high light stress.ConclusionThe results obtained in this study demonstrate that the accumulation of ascorbate and glutathione in chloroplasts, peroxisomes and the cytosol is an important reaction of plants to short term high light stress. The accumulation of ascorbate and H2O2 along the tonoplast and in vacuoles during these conditions indicates an important route for H2O2 detoxification under these conditions.

Putative role of the malate valve enzyme NADP–malate dehydrogenase in H 2 O 2 signalling in Arabidopsis

“…Further studies are needed to confirm the presence of the thiol-modulating compounds in peroxisomes. Furthermore, the glutathione level has been recently shown to increase in peroxisomes of mesophyll cells when Arabidopsis plants are exposed to high light [42]. Inactivation of catalase strongly impacts the leaf glutathione status, because photorespiratory H 2 O 2 production increases the total glutathione content and leads to a dramatic oxidation of the glutathione pool in the Arabidopsis cat2 mutant [12].…”

A Secreted Effector Protein ofUstilago maydisGuides Maize Leaf Cells to Form Tumors

“…Preparation of samples for TEM and immunogold labeling was performed as described previously (Heyneke et al, 2013). Small samples (;1.5 mm 2 ) from at least 12 different leaves were cut on a modeling wax plate in a drop of 2.5% (w/v) paraformaldehyde and 0.5% (v/v) glutaraldehyde in 0.06 M Sørensen phosphate buffer, pH 7.2.…”

Interacting effects of high light and elevated CO2 on the nutraceutical quality of two differently pigmented Lactuca sativa cultivars (Blonde of Paris Batavia and Oak Leaf)

“…The plant may also increase electron diversion to alternative sinks, such as the Mehler reaction, thus requiring more antioxidant compounds (Smirnoff, 1993). The light intensity has been shown to positively correlate with the concentrations of total ascorbate, glutathione and total phenols in several species (Cakmak and Marschner, 1992;Samuolienė et al, 2011;Heyneke et al, 2013). These results indicate that the different nutritional attributes that define the nutritional quality (minerals, carbohydrates, proteins and antioxidants) and growth respond to high light conditions; thus, controlling the light intensity could improve a plant's nutraceutical attributes.…”