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The present study was conducted to investigate the evaluation of antimycin A (AA) as a modulator of the alternative respiratory pathway (AP) on the intensity of growth processes and some physiological parameters of etiolated wheat seedlings, such as maximum length of root, length of first leaf and coleoptile, fresh and dry weights at the whole plant level, leaf area as well as relative water content, saturation water deficit, degree of leaf succulence and sclerophylly. Generally, exposure to heat stress (HS) alone caused a noticeable reduction in root length (59%), leaf length (30%), plant fresh mass (10%), dry mass (14%), and leaf area (25%) which was consistent with the progressive alteration in water relations. Furthermore, the degree of leaf succulence and degree of leaf sclerophylly were severely affected by HS in wheat seedlings. However, the results demonstrated that the application of AA did not induce such a significant reduction in the leaf length (23%), coleoptile length (5%), plant fresh weight (7%), plant dry weight (3%), and leaf area (21%) as well as water relations in etiolated wheat seedlings compared to heat-stressed plants. Taken together, the activation of AP promoted a mitigating of the damaging effect of HS in wheat seedlings supporting growth processes.

Global warming can negatively affect freshwater macrophytes. However, the degree to which freshwater plants can survive after long-term or short-term warming and the underlying molecular mechanisms are not fully understood. The aim of our study was to analyze the responses of an invasive plant to moderate heat stress (HS). Biochemical and physiological stress responses to experimental warming (30Ѓ}1.0°C/25Ѓ}1.0°C, day/night) were assessed in the invasive waterweed Elodea canadensis. The effect of the moderate HS on the macrophyte was evaluated through changes in the total protein content, catalase activity, lipid peroxidation, cellular membrane permeability by electrolyte leakage and the concentrations of carotenoids and photosynthetic pigments. Catalase activity and carotenoid concentrations increased significantly (p

The objective of the present investigation was to identify the effect of antimycin A (AA) as an activator of the alternative pathway (AP) of respiration, on oxidative stress intensity, the level of lipid peroxidation (LPO) and activities of H2O2 scavenging enzymes in functionally different organs of Triticum aestivum L. subjected to short- and long-term exposure to high temperature (HT). The level of LPO was assessed in terms of malondialdehyde (MDA), an indicator of oxidative injury. The results demonstrated increases in the total content of reactive oxygen species (ROS) and MDA production in developing and senescent organs of wheat seedlings, and significant augmentation of the activities of the antioxidant enzymes, catalase and ascorbate peroxidase, in different organs in response to exposure to HT. The activation of the AP by AA restrained ROS production in the mitochondrial electron transport chain (mETC) under exposure to HT.

This study was conducted to evaluate the dynamics of superoxide anion radical (O•2–) production rate and alterations in DNA content and permeability of cell membranes in etiolated wheat seedlings (Triticum aestivum L. cv. Harmony) as well as those grown under normal daylight regime. The results suggest that the development of etiolated wheat seedlings and those grown under normal daylight is accompanied by the periodic formation of O•2– which leads to alterations in DNA content as well as the permeability of cell membranes. The results also indicate that the first enhancement in the rate of O•2– generation was detected on the sixth and seventh days of development, after which the rate of O•2¯ production reduced in etiolated seedlings and those grown under normal daylight regime. The second maximum of the O•2¯ producing rate in developing and senescent organs occurred on the ninth day of plant development. The lowest values of all studied parameters, such as O•2– producing rate (37%), total genomic DNA concentration (58%) and electrolyte leakage (EL; 18%) were observed in etiolated wheat seedlings. Towards the end of the study period, DNA concentration and EL in organs of wheat seedlings declined, suggesting possible destruction of cellular organelles and the beginning of apoptotic processes. Overall, these results indicate that O•2– generation is decisive for normal morphogenesis, and it is an indispensable element of synchronous growth and development. [ABSTRACT FROM AUTHOR]

The research was aimed at evaluating the dynamics of superoxide anion radical (O2˙ˉ) producing rate and alterations in genomic DNA and protein concentrations in apical and basal parts of etiolated wheat coleoptiles as well as grown under normal daylight regime. The results indicate that the development of wheat coleoptiles was accompanied by the periodic formation of O2˙ˉ in both apical and basal parts, which led to alterations in DNA and protein contents. It is noteworthy that the first enhancement in the rate of O2˙ˉ generation was detected on the 7th day of development and the second maximum on the 9th day of development. DNA and protein concentrations declined with coleoptiles age, especially in the apical part, thus suggesting the destruction of cellular organelles eventually leading to cell death. Collectively, these results indicate that O2˙ˉ generation is essential for many aspects of plant life, including synchronous growth and development [ABSTRACT FROM AUTHOR]

The present study was conducted to investigate the evaluation of antimycin A (AA) as a modulator of the alternative respiratory pathway (AP) on the intensity of growth processes and some physiological parameters of etiolated wheat seedlings, such as maximum length of root, length of first leaf and coleoptile, fresh and dry weights at the whole plant level, leaf area as well as relative water content, saturation water deficit, degree of leaf succulence and sclerophylly. Generally, exposure to heat stress (HS) alone caused a noticeable reduction in root length (59%), leaf length (30%), plant fresh mass (10%), dry mass (14%), and leaf area (25%) which was consistent with the progressive alteration in water relations. Furthermore, the degree of leaf succulence and degree of leaf sclerophylly were severely affected by HS in wheat seedlings. However, the results demonstrated that the application of AA did not induce such a significant reduction in the leaf length (23%), coleoptile length (5%), plant fresh weight (7%), plant dry weight (3%), and leaf area (21%) as well as water relations in etiolated wheat seedlings compared to heat-stressed plants. Taken together, the activation of AP promoted a mitigating of the damaging effect of HS in wheat seedlings supporting growth processes. [ABSTRACT FROM AUTHOR]

The present study was aimed to study the plasticity of the antioxidative defense system in the etiolated leaves of Triticum aestivum L. and grown under normal daylight conditions following short-term and long-term high temperature (HT), as well as to investigate the role of antimycin A (AA) as an activator of the alternative respiratory pathway (AP) under stressful conditions. Wheat seedlings exposed to short-term HT (42°C) showed no significant changes in Mn-superoxide dismutase (SOD) activity but following prolonged HT a pronounced induction of CuZn-SOD activity was detected. Catalase and ascorbate peroxidase activities increased in response to short-term and long-term HT treatments by 24 and 42%, respectively. Treatment with AA showed a significant decrease in the activities of antioxidative enzymes in etiolated leaves and grown under normal daylight. Modulation of the AP by AA in leaves of wheat seedlings might be responsible for conferring tolerance to HT in wheat seedlings preventing oxidative stress [ABSTRACT FROM AUTHOR]

The effect of antimycin A (AA) as a possible activator of the alternative pathway (AP) was assessed on photosynthetic pigment composition and chlorophyll (Chl) fluorescence parameters in response to heat stress (HS) (42°C) in etiolated wheat (Triticum aestivum L., var. Harmony) seedlings. Results indicate that pigment concentrations significantly decreased (20-70%) following long-term HS, while the short-term exposure resulted in a 16-56% decline in etiolated wheat seedlings. It was observed that short-term and long-term HS altered photosystem (PSII) functionality in leaves, which was evidenced by a low maximum photochemical efficiency of PS II (Fv/Fm), a maximum fluorescence yield in the dark-adapted state (Fm), and by a high minimal fluorescence yield in the dark-adapted state (F0). However, at the same time AA reduced the negative effect of HS, suggesting that the activation of the AP induced by AA displayed tolerance to stress contributing the stabilization of the photosynthetic apparatus in etiolated wheat seedlings under HS. [ABSTRACT FROM AUTHOR]

The impact of antimycin A (AA) as a possible modulator of the alternative pathway (AP) was investigated on some biochemical parameters such as the rate of superoxide (O2-) production and antioxidant status in response to high temperature (HT) (42°C) in the leaves of wheat seedlings at the early and late stages of development. It was observed that the rate of O2- production and activities of the antioxidative defence system significantly increased following HT. However, a significant decrease of the rate of O2- production and activities of antioxidative enzymes was detected in the leaves of wheat seedlings under the combined effect of AA and HT. This finding suggests the activation of the AP by AA in leaves of wheat seedlings that prevented oxidative stress caused by HT. [ABSTRACT FROM AUTHOR]

In this study we used spectrophotometry to investigate the effect of negative concentrations of sodium chloride ions on photosynthetic pigments in Elodea canadensis (Michx. 1803). The concentrations of pigments, carotenoids, chlorophyll a and chlorophyll b, in plant leaves provide information about the physiological state of plants and were determined using a spectrophotometer. Quantity and dynamics analyses of photosynthetic pigments are effective methods which allow determining changes in metabolites of plant cells even at insignificant cellular damage. During this research photosynthetic pigments in leaves were obtained at the different sodium chloride levels: 0.0, 0.025, 0.05, 0.1, 0.5 and 1.0 M. The results of this research indicate that these types of stressors at high concentrations: 0.1, 0.5 and 1.0 M after a prolonged time of impact on plant leaves lead to a decrease of photosynthetic pigments and inhibit growth and development of a plant as a whole. [ABSTRACT FROM AUTHOR]