Content Of Low Molecular Antioxidants Research Articles

Antioxidant status of barley seedlings under conditions of excess manganese

The system of protection against the effects of heavy metals (TM) can differ not only in different species of plants, but also in different varieties. Manganese (Mn), as a biogenic element, is necessary for normal plant growth and development. However, in the case of concentrations exceeding the optimal level, it negatively affects both linear plant growth and physiological processes. The paper presents data on the assessment of the effect of excess manganese (II) ions (30, 60 and 90 mg/l of active substance) on barley seedlings of different varieties. Resistance of plants to ionic toxicity of manganese (II) was judged by the value of antioxidant activity (AOA) of superoxide dismutase (SOD), the content of low-molecular antioxidants (chlorophyll a and b, carotenoids and anthocyanins) in barley leaves. For most of the varieties studied, an increase in AOA of SOD, the content of anthocyanins indicating the activation of plant protective mechanisms, was noted. The amount of green pigments, as well as carotenoids, on the contrary, decreased, compared with the control, which indicated a violation of the processes of photosynthesis in them.

Variation in the seed progeny of smooth brome grass, Bromus inermis Leyss., under conditions of chronic irradiation in the zone of the Eastern Ural Radioactive Trace

Long-term studies have been performed on the seed progeny of B. inermis from test plots established along the radioactive contamination gradient in the zone of the Eastern Ural Radioactive Trace (EURT), where dose loads on maternal plants and embryos of seeds from chronically irradiated cenopopulations (with natural background radiation taken into account) exceed control values by factors of 2 to 107. Interannual and individual variation in the viability, mutability, and radiosensitivity of the seed progeny has been revealed. Against the background of high interpopulation variation in test parameters in the EURT zone, weather conditions appear to have no significant effect on seed quality, while such effects are appreciable in background cenopopulations. It has been shown that a positive correlation exist between the initial viability of the seed progeny and their radioresistance. Chronic irradiation in a wide dose range induces an increased frequency of different mutations and morphological modifications. The contents of low-molecular antioxidants in seedlings from impact cenopopulations proved to be higher than in the background sample. The results obtained characterize the potential of protective and restorative mechanisms acquired in the course of evolution that allow plants to survive in the changing environment under exposure to technogenic stress.

Аскорбат-глутатіонова система захисту рослин кукурудзи в умовах дії іонів нікелю

Influence of nickel ions on growth reaction in maize seedlings of Orjitza 237MV hybrid and the content of low-molecular antioxidants in assimilation organs are investigated. The dependence of morphometric parameters of seedling roots and sprouts on the concentration of nickel ions is established. Considerable depression of growth and development of vegetative organs at a juvenile period occurs under long-term action of the metal in concentrations of 0.05–1.00 mM/l. The changes of reduced glutathione and ascorbic acid content under nickel ions influence are found in the leaves photosynthesizing tissue of the maize seedlings. It leads to a variation of the reducing activity in the tissues. The given fact can testify to an oxidizing stress under nickel ions effect and to participation of the low-molecular antioxidants in the plants adaptation to xenobiotics influence. Period of renewal of the glutathione and ascorbic acid metabolism in experimental samples was determined by the concentration of the nickel nitrate.

Effect of anthropogenic pollution with dust containing heavy metals on seed progeny of spear saltbush

The influence of anthropogenic pollution with dust containing heavy metals on changes in physiological, cytological, and biochemical characteristics of spear saltbrush (Artiplex patula L.) seed progeny grown under conditions of extreme continental climate and permafrost in Central Yakutia was studied. Anthropogenic pollution with such dust of the parent habitat led to the decrease in physiological characteristics of seed progeny: germinability, root length. In this case, there was an increase in the lipid peroxidation intensity, the contents of low-molecular antioxidants and activity of antioxidant enzymes, and also the rate of molecular-genetic processes (replication and reparation of DNA, protein translation) against the backgrounds of a relatively small increase in mitotic activity in seedlings grown from produced seeds as compared with control. This can be considered as adaptive responses of A. patula to the action of chronic anthropogenic environmental stressor in a certain range of its intensity.

Assessment of radiation impact on Stellaria graminea cenopopulations in the zone of the Eastern Ural Radioactive Trace

The seed progeny of the little starwort (Stellaria graminea) growing in the zone of the Eastern Ural Radioactive Trace (EURT) and in background areas was studied. The radiation exposure of this species in the EURT zone was three orders of magnitude higher than in the background. Evidence was obtained for high interannual variation in seed viability and tolerance to additional acute irradiation, but no specific connection was revealed between these parameters and radioactive contamination level in plant habitats. Weather conditions are an important source of variation in seed viability, but significant influence of temperature and precipitation was revealed only for cenopopulations of the EURT. The proportion of seedlings with morphoses in samples from the EURT was found to be increased; additional irradiation facilitated the detection of latent abnormalities. A negative correlation between seedling survival rate and the content of low-molecular antioxidants in the seedlings was revealed in all test areas. The allozyme structure of starwort cenopopulation was analyzed for the first time. A directed switch of allele frequencies at loci Pgi-2 and Fdh was revealed in samples from the EURT.

Barley leaf antioxidant system under photooxidative stress induced by Rose Bengal

The effects of photooxidative stress induced in green barley (Hordeum vulgare L.) leaves by xanthene dye Rose Bengal (RB) on the content of low-molecular antioxidants and the activity of antioxidant enzymes were studied. During illumination (24 h, 160 mol quanta/(m2 s)) of the leaves preincubated in darkness on 10 and 100 M RB, ROS accumulated, and their level increased along with RB concentration and duration of illumination. Under these conditions, the content of reduced ascorbate and reduced glutathione (GSH) increased, the level of -and -tocopherol decreased, and the activity of ascorbate peroxidase, the enzyme participating in H2O2 degradation, increased. At the same time, the activity of catalase, also participating in H2O2 detoxification, decreased, which may be due to the enzyme inhibition during the photochemical stress. In the illuminated treated leaves, superoxide dismutase (SOD), the enzyme destroying the superoxide anion radicals, was activated. The cytosolic SOD isoform was the first to be activated and chloroplastic isoforms followed. It is supposed that photodynamic processes induced by RB in barley leaves are initiated in the cytosol. The activity of glutathione reductase, participating in glutathione oxidized form reduction, did not change at first and grew only after continuous illumination. Thus, the increase in the GSH level, which we have revealed on the initial stage of photooxidative stress development, was due to its synthesis de novo. In addition, under photooxidative stress induced by the sensitizer RB, the level of tocopherol reduced, whereas the amount of other low-molecular antioxidants increased. The exhaustion of the tocopherol pool, in its turn, could limit the resistance of barley leaves to the photooxidative stress.

Effect of low above-zero temperature on the content of low-molecular antioxidants and activities of antioxidant enzymes in green barley leaves

We studied the effect of low above-zero temperature (2°C) on the content of low-molecular antioxidants (ascorbic acid, glutathione, and carotenoids) and also activities of antioxidant enzymes (ascorbate peroxidase, APO; catalase, CAT; glutathione reductase, GR; and superoxide dismutase, SOD) in green barley (Hordeum vulgare L.) seedlings. Under stress conditions, the content of low-molecular antioxidants, especially that of reduced ascorbate form, increased. Low-temperature stress activated APO, CAT, GR, and SOD. First enzymes responding to the action of stress factor were APO and CAT, i.e., enzymes neutralizing hydrogen peroxide in plant cells, which indicated H2O2 active generation at low temperature. Cytoplasmic SOD was more active than its chloroplast isoforms. This indicates that oxidative process initiation under low-temperature stress occurred more active in the cytosol. After termination of stress-factor action, the content of total ascorbate, glutathione, and carotenoids reduced rapidly to the level close to the initial one. During post-stress period, the amount of reduced ascorbate declined as well; however, it remained at the level higher than the initial one. Activities of APO and CAT dropped sharply; activities of GR and SOD reduced gradually. Thus, reduced ascorbate, APO, and CAT play an important role in plant cell defense against above-zero temperatures close to zero; reduced ascorbate, GR, and SOD are especially important during post-stress period.