Abstract
Chilling temperatures (1-10 oC) are known to disturb cellular physiology, cause oxidative stress via creating imbalance between generation and metabolism of reactive oxygen species (ROS) leading finally to cell and/or plant death. Owing to known significance of low molecular antioxidants - ascorbic acid (AsA) and glutathione (GSH) in plant stress-tolerance, this work analyzes the role of exogenously applied AsA and GSH in the alleviation of chilling stress (3°C)-impact in cucumber (Cucumis sativus L. cv. Vjaznikowskij 37) plants. Results revealed AsA and GSH concentration dependent metabolism of ROS such as superoxide (O2•‾) and the mitigation of ROS-effects such as lipid peroxidation (LPO) as well as membrane permeability (measured as electrolyte leakage) in C. sativus leaf discs. AsA concentration (750 µM) and GSH (100 µM) exhibited maximum reduction in O2•‾ generation, LPO intensity as well as electrolyte leakage, all of these were increased in cold water (3°C and 25°C)-treated leaf discs. However, AsA, in particular, had a pronounced antioxidative effect, more expressed in case of leaf discs during chilling (3°C); whereas, at temperature 25°C, some AsA concentrations (such as 50 and 100 mM AsA) exhibited a prooxidative effect that requires molecular-genetic studies. Overall, it is inferred that AsA and GSH have high potential for sustainably increasing chilling-resistance in plants.
Highlights
Sub-optimal temperatures are among the major environmental factors known to impact crop productivity via affecting growth, development and metabolism especially in the tropics and subtropics (Lukatkin et al, 2012; Li et al, 2014)
The results presented below describe the significant responses of O2− generation, lipid peroxidation (LPO) and electrolyte leakage considering ascorbic acid (AsA) followed by GSH in chilling experiments with leaf discs
SUPEROXIDE ION STATUS IN LEAF DISCS UNDER TEMPERATURE REGIMES (25 AND 3◦C), AND WITH ASCORBIC ACID AND GLUTATHIONE The pattern of AsA effect on O2− generation exhibited its dependency on AsA concentration and temperature regimes (Table 1)
Summary
Sub-optimal (low non-freezing/chilling) temperatures are among the major environmental factors known to impact crop productivity via affecting growth, development and metabolism especially in the tropics and subtropics (Lukatkin et al, 2012; Li et al, 2014). To efficiently counteract ROS-mediated potential consequences, plants employ enzymatic (SOD, superoxide dismutase; CAT, catalase; GPX, guaiacol peroxidase; GST, glutathione sulfo-transferase; APX, ascorbate peroxidase; MDHAR, monodehydroascorbate reductase; DHAR, dehydroascorbate reductase; GR, glutathione reductase) and non-enzymatic (ascorbic acid, AsA; glutathione, GSH; carotenoids; tocopherols; phenolics) antioxidants-based defense system (Anjum et al, 2010, 2012, 2014b; Gill and Tuteja, 2010)
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