Open Access
Access granted
Subscription Access
Vol 72, No 2 (2025)
ЭКСПЕРИМЕНТАЛЬНЫЕ СТАТЬИ
Respiratory Response of Arabidopsis thaliana Plants with NPQ1 Suppression to High Light: Some Aspects of the Functional Interaction of Chloroplasts and Mitochondria
Abstract
The energy-dissipating systems (EDS) of a photosynthetic cell — the violaxanthin cycle (VXC) in chloroplasts and the alternative respiratory pathway (AP) in mitochondria — are involved in protecting against excess light energy. The mechanisms of functional interaction of EDS are poorly understood. The aim was to study the effect of high light on respiration and AP activity in Arabidopsis thaliana plants with suppression of NPQ1 encoding the VXC enzyme — violaxanthine de-epoxidase. Four-week-old plants of npq1 line and Columbia-0 wild type line (Col-0) grown at 90 mmol/(m2 s) were exposed to high light, 400 mmol/(m2 s), for 8 hours. Under stress conditions, the npq1 line showed significantly lower values of non-photochemical quenching of chlorophyll fluorescence and the level of de-epoxidation compared to the wild-type line (Col-0), which indicated the absence of zeaxanthin-dependent protection of the photosynthetic apparatus. The plants of the mutant line reacted to high light by increasing respiration due to activation of both alternative and cytochrome pathways. At the same time, the part of AP from total respiration in the npq1 line was consistently high and amounted to about 50%, regardless of the light conditions. Activation of AP and accumulation of the alternative oxidase (AOX) protein were obviously facilitated by increased expression of most AOX genes, the level of transcripts of which was higher under control conditions (0 h), but decreased by the end of the experiment. At the same time, the amount of mRNA of the most stress-inducible AOX1a gene was the lowest among all AOX genes. It is assumed that in the npq1 line the signaling pathway supported by the transcriptional factor of MYB4, a negative regulator of phenylpropanoid synthesis, is weakened. This could be the reason for the low expression of AOX1a, which contains a large number of MYB4-binding sites in the promoter, and an increased content of anthocyanins in leaves compared to Col-0. Unlike Col-0 plants, the npq1 line was characterized by half the activity of superoxide dismutase (SOD), with a predominance of Fe-SOD localized mainly in chloroplasts. However, based on the content of superoxide anion radical and hydrogen peroxide, plants of the npq1 line showed a higher level of oxidative reactions in high-light conditions compared with the wild type line. The data obtained showed a reduced ability of plants with suppression of the genes of two key components of energy-dissipating systems (NPQ1 and AOX1a) to withstand stress. The results indicate the mutual regulation of the EDS of mitochondria and chloroplasts to protect against photooxidation, the importance of AOX in the modulation of respiratory function, and the existence of fast adaptive metabolic rearrangements that provide plant viability under stressful conditions.
Advances in Chemical Physics. 2025;72(2):81-99
81-99
Energy and Pro-/Antioxidant Metabolism of Rhodiola rosea L. Buds During the Annual Growth Cycle
Abstract
Data on changes in the energy status and pro-/antioxidant metabolism activity at different stages of the dormancy and upon emergence from it in Rhodiola rosea L. buds were obtained. A significant degree of water content (70–75%) and a low proportion of free water (50%) during the overwintering of buds were demonstrated. The freezing temperature of free water ranged from –6°C to –8°C, reflecting the high degree of meristematic tissues adaptation to low temperatures. During autumn-winter morphogenesis (from August to January), buds demonstrated stable rates of heat generation and O2 uptake, and a high proportion of cytochrome respiration (more than 70%). In January, compared to autumn, a significant increase in the rate and efficiency of energy storage and an increase in provxidant levels (the content of thiobarbituric acid reactive substances (TBARS) and H2O2 content) were observed. During dormancy emergence in spring, an increase in rate of heat production and respiratory capacity, but a decrease in the energetically efficiency of respiration were observed. Compared to the autumn-winter period, the activity of energetically inefficient alternative respiration increased 4.5 times in spring, suggesting the involvement of alternative oxidase in maintaining pro-/antioxidant metabolism and plant adaptation to spring temperature fluctuations and increased insolation. In spring, compared to the dormant period, we observed a peak in provxidants accumulation and antioxidant enzymes activity. The maximal diversity and activity of SOD isoforms during spring morphogenesis may be related to the accumulation of H2O2 in various cellular compartments, as a stable ROS and an important signaling molecule. We concluded that Rhodiola rosea plants adapted to more favorable conditions do not exhibit the deep, organic dormancy which is characteristic of natural conditions. Energy metabolism parameters, the capacity and ratio of the cytochrome and alternative respiratory pathways, provxidants content and antioxidant enzymes activity can serve as physiological and biochemical markers of dormancy maintenance and emergence in Rhodiola rosea buds.
Advances in Chemical Physics. 2025;72(2):100-114
100-114
Pigment Complex of Plant Sprouts from Different Ecological and Geographical Locations
Abstract
The pigment complex and its effect on the survival of seedlings of the daughter generation of common tansy (Tanacetum vulgare L.) and common wormwood (Artemisia vulgaris L.) were studied, the parent forms of which grew in different ecological and geographical conditions (the cities of Kaliningrad, Belgorod, Ulan-Ude, Yakutsk, Magadan, and Srednekolymsk). The results are discussed based on the working hypothesis that seedling survival is largely determined by the pigment complex formed by maternal plants grown in different ecological and geographical conditions. It was found that the content of chlorophyll a (Ch A) in plant seedlings varied widely. The maximum chlorophyll b (Ch B) content was found in seedlings of T. vulgare from the Ulan-Ude and Yakutsk ecotypes. The results confirm that one of the most important conditions determining the carotenoid (Car) pool in plants is the duration of solar insolation during the growing season. The ratio of the sum of chlorophylls to the sum of carotenoids (Ch/Car) showed a high positive correlation with the duration of solar insolation at the seed collection sites in July. It has been shown that total July insolation (> 200 hours) on T. vulgare mother plants has a beneficial effect on photosynthesis and seedling survival. The survival rate of A. vulgaris seedlings is most likely determined not by the Ch/Car ratio, but by other evolutionarily formed factors of the habitat of the parent plants. Thus, the adaptive changes of wild plants to light conditions lead to changes in the content and ratio of pigments. Seedlings whose seeds were formed under conditions of prolonged solar insolation (Yakutsk, Ulan-Ude) contain the highest amount of chlorophylls and carotenoids, which affects their survival.
Advances in Chemical Physics. 2025;72(2):115-122
115-122
Comprehensive Analysis of Biochemical Adaptations of Balsamic Poplar (Populus balsamifera L.) to Technogenic Stress in Sanitary Protective Plantations
Abstract
A comprehensive study of the biochemical adaptations of balsam poplar (Populus balsamifera L.) growing in sanitary protection plantations of the Sterlitamak Industrial Center (SIC) was conducted. A deterioration in the vital condition of balsam poplar under conditions of industrial pollution was established. An increase in the content of gross forms of heavy metals in the soils of the industrial zone was detected, with maximum concentrations in the surface layer (0–20 cm). It was found that an excess of some heavy metals leads to a decrease in the magnesium content in poplar leaves under SIC conditions. In the zone of the highest concentration of toxicants (2–3 km from sources of petrochemical and chemical pollution), an increase in the level of hydrogen peroxide in the leaves by 41.22% was recorded compared to the conditional control zone (10–15 km from the industrial zone). Industrial emissions from city enterprises stimulated oxidative processes in poplar leaves, manifested by an increase in malondialdehyde content (by 33.73%) compared to the conditional control zone. A decrease in flavonol content and catalase activity, an enzyme in the plant antioxidant system, was demonstrated under SIC conditions. Apparently, under stress, plants utilize catalases, flavonols, and other phenolic compounds to reduce the intensification of lipid peroxidation processes. It was found that under SIC pollution, the decrease in flavonols can be compensated for by an increase in anthocyanins. During the active growing season (June-July), a decrease in chlorophyll content was recorded in the leaves of trees in the industrial zone compared to the control zone. It is concluded that technogenic pollution leads to the accumulation of heavy metals in soils, the development of oxidative stress, and the restructuring of the antioxidant system in poplar leaves. A decrease in chlorophyll content can serve as a diagnostic sign of physiological damage to balsam poplars due to exposure to industrial pollution. The detected biochemical changes represent a complex of adaptive responses by plants to industrial stress.
Advances in Chemical Physics. 2025;72(2):123-134
123-134
ОБЗОР
Modification of the Lighting Conditions to Increase Plant Productivity and Nutritional Value: New Solutions
Abstract
The review summarizes the results of numerous studies aimed at optimizing plant production in closed systems (greenhouses with controlled climate and plant factories with artificial lighting (vertical farms)). The latest pre-harvest or end-of-production light treatments are considered. These include an increase in the lighting duration (up to continuous lighting), an increase in the light intensity, a change in the light quality (different ratios of red, blue, green light, the use of far-red light) or additional illumination with UV light (usually for several days). Unlike the lighting strategies used in the first part of the production cycle and aimed at optimizing the growth, development and biomass accumulation, their application is carried out in order to increase not only yield, but also the nutritional value of products, reduce nitrate content, as well as increase the energy efficiency of production. Some physiological and biochemical mechanisms that are involved in plant response to various light treatments are discussed, and the need to further study the molecular and genetic mechanisms that underlie these responses is emphasized, knowledge of which will accelerate the search and identification of the most effective agricultural practices that increase crop productivity and nutritional value.
Advances in Chemical Physics. 2025;72(2):135–153
135–153