Accumulation Of Photosynthetic Pigments Research Articles

Growth, Physiological, and Biochemical Responses of a Medicinal Plant Launaea sarmentosa to Salinity

Launaea sarmentosa is a valuable medicinal plant with adaptability in saline areas, but it is still unclear how it responds to salinity. For the first time, the present study examined the plant’s changes under different soil salinities generated by 50, 100, 200, and 400 mM NaCl in order to elucidate its responses in terms of growth, photosynthesis, water uptake, osmotic adjustment, ion homeostasis, and oxidative stress defense to salinity. The results showed that the plant’s growth was enhanced by 50 mM NaCl with an 18.07% increase in dry biomass compared to the control, whereas higher salinity levels reduced its growth with a 6.39–54.85% decrease in dry biomass. The plant’s growth response indicates that it had tolerance to salinity levels up to 400 mM NaCl. The accumulation of photosynthetic pigments, including chlorophylls (a + b) and carotenoids, was enhanced under salinity, except for a reduced accumulation under 400 mM NaCl. Relative water content decreased while proline content increased in the salt-stressed plants. Moreover, the salt-stressed plants reduced their K+ and NO3− content along with increases in Na+ and Cl− content. The high salt stress level also caused oxidative stress in the plants, which was revealed through the accumulation of malondialdehyde and hydrogen peroxide content. In addition, the salt-stressed plants had increased total phenolic content and the activities of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase. These physiological and biochemical changes suggest that L. sarmentosa evolved adaptive mechanisms in photosynthesis, osmotic adjustment, ion homeostasis, and antioxidant defense for growing under salt stress.

Seasonal dynamics of photosynthetic pigments (chlorophylls a, b and carotenoids) in woody plants of the Altai Botanical Garden

This article reflects the results of studies of photosynthetic pigments (chlorophylls a, b and carotenoids) in 14 species of deciduous plants (trees and shrubs) and one coniferous Juniperus sabina L. in the Altai Botanical Garden during two growing seasons. The following species have a high accumulation of pigments: Acer tataricum L., Juglans cinerea L., Tilia cordata L., Corylus avellana L., Cotoneaster lucidus Schlecht., Lonicera tatarica L. For the coniferous species Juniperus sabina L. low levels of chlorophylls a, b and carotenoids are characteristic. Berberis thunbergii DC is also distinguished by a low accumulation of photosynthetic pigments. Minor differences between the species were noted in the content of carotenoids, twelve species were included in the group with low and medium content of this pigment. There is no definite pattern in the accumulation of carotenoids, and the data on the types and number of yellow pigments do not differ significantly. As a result of the conducted studies, a correlation was revealed between the content of carotenoids and the content of chlorophyll a in most species. The data obtained indicate the presence of species specificity in the content of chlorophylls a, b and carotenoids. Also, the photosynthetic apparatus of woody plants is sensitive to light and water conditions

Peculiarities of biochemical and mineral composition of lettuce <i>Lactuca sativa</i> L. grown from seeds after long-term storage in the International Space Station

Seed storage of agricultural crops in the conditions of International Space Station (ISS) is an effective method of quick plant breeding aimed to enhance the adaptability, and improve the biologically active compound accumulation and crop yield. Biochemical and mineral composition (ICP-MS) of lettuce grown in greenhouse from seeds stored for one year at the ISS was assessed. High varietal differences in lettuce tolerance to the effect of micro-gravity and radiation were evaluated using the values of yield, biometrical parameters, antioxidant status and plant mineral composition. Among the cultivars studied, i.e. Petrovich, Synthesis, Moskovsky parnikovy, Picnic, Cavalier and Bouquet, only the cvs. Retrovich, Synthesis, Moskovsky parnikovy and Picnik retained seed viability. Significant yield increase was recorded for the cv. Moskovsky parnikovy, while the cvs. Petrovich, Synthesis and Picnic demonstrated a tendency to the yield decrease. Improvement of photosynthetic pigment accumulation due to seed space storage was recorded for the cv. Moskovsky parnikovy and, particularly, the latter cultivar differed from the other cvs. due to the significantly higher proline level and lower MDA levels in leaves. Though space stress did not cause any significant decrease in antioxidant accumulation of plants, the latter demonstrated valuable changes in mineral composition. Among the 23 elements tested, V, Se. Fe and Cr showed higher concentrations compared to those in the control plants. Positive correlations between Ca, Sr, Cd, Cp, Mg, Mo and Pb were recorded (r > 0.9; p < 0.001).

Effects of chemical oxygen demand and chloramphenicol on attached microalgae growth: Physicochemical properties and microscopic mass transfer in biofilm

During the wastewater treatment and resource recovery process by attached microalgae, the chemical oxygen demand (COD) can cause biotic contamination in algal culture systems, which can be mitigated by adding an appropriate dosage of antibiotics. The transport of COD and additive antibiotic (chloramphenicol, CAP) in algal biofilms and their influence on algal physiology were studied. The results showed that COD (60 mg/L) affected key metabolic pathways, such as photosystem II and oxidative phosphorylation, improved biofilm autotrophic and heterotrophic metabolic intensities, increased nutrient demand, and promoted biomass accumulation by 55.9 %, which was the most suitable COD concentration for attached microalgae. CAP (5–10 mg/L) effectively stimulated photosynthetic pigment accumulation and nutrient utilization in pelagic microalgal cells. In conclusion, controlling the COD concentration (approximately 60 mg/L) in the medium and adding the appropriate CAP concentration (5–10 mg/L) are conducive to improving attached microalgal biomass production and resource recovery potential from wastewater.

Alleviation of cotton growth suppression caused by salinity through biochar is strongly linked to the microbial metabolic potential in saline-alkali soil

Biochar is a typical soil organic amendment; however, there is limited understanding of its impact on the metabolic characteristics of microorganisms in saline-alkaline soil microenvironment, as well as the advantages and disadvantages of plant-microorganism interactions. To elucidate the mechanisms underlying the impact of saline-alkali stress on cotton, a 6-month pot experiment was conducted, involving the sowing of cotton seedlings in saline-alkali soil. Three different biochar application levels were established: 0 % (C0), 1 % (C1), and 2 % (C2). Results indicated that biochar addition improved the biomass of cotton plants, especially under C2 treatment; the dry weight of cotton bolls were 8.15 times that of C0. Biochar application led to a rise in the accumulation of photosynthetic pigments by 8.30–51.89 % and carbohydrates by 7.4–10.7 times, respectively. Moreover, peroxidase (POD) activity, the content of glutathione (GSH), and ascorbic acid (ASA) were elevated by 23.97 %, 118.39 %, and 48.30 % under C2 treatment, respectively. Biochar caused a reduction in Na+ uptake by 8.21–39.47 %, relative electrical conductivity (REC) of plants, and improved K+/Na+ and Ca2+/Na+ ratio indicating that biochar alleviated salinity-caused growth reduction. Additionally, the application of biochar enhanced the absorption intensity of polysaccharide fingerprints in cotton leaves and roots. Two-factor co-occurrence analysis indicated that the key differential metabolites connected to several metabolic pathways were L-phenylalanine, piperidine, L-tryptophan, and allysine. Interestingly, biochar altered the metabolic characteristics of saline-alkali soil, especially related to the biosynthesis and metabolism of amino acids and purine metabolism. In conclusion, this study demonstrates that biochar may be advantageous in saline soil microenvironment; it has a favorable impact on how plants and soil microbial metabolism interact.

Integrated field application of T. viride, botanicals, and fungicides for managing early blight (Alternaria solani) and enhancement of plant growth, tuber nutritional quality, and potato yield

Early blight disease, incited by Alternaria solani, is the most deleterious foliar disease of potato and other solanaceous crops. Herein, to counter the early blight disease, T. viride (Tv), botanicals [neem (N) and garlic (G)], and fungicides [flusilazole (F) and kasugamycin (K)] in different combinations applied through tuber treatment (ST) and foliar spray (FS) were evaluated for disease suppression, germination percent, plant growth promotion, photosynthetic pigments, and yield components as well as the nutritional quality of tubers under field conditions during the 2018–2019 and 2019–2020 seasons. The results of two-year field experiments revealed that the combination of Tv+ F+ N (ST) + G+K (FS) efficiently suppressed the development of the early blight disease symptoms and recorded 21.63 and 18.37% disease severity (DS) as compared to untreated control, respectively at 30 days post-treatment (dpt). During the 2018–2019 seasons, potato tubers treated with Tv +F significantly increased tuber germination (97.78%), while Tv+ F+ N treated potato tubers exhibited 98.89% tuber germination during the 2019–2020 season. Additionally, the potato plants treated with the combination of Tv+ F+ N (ST) + G+K (FS) and challenge inoculated with A. solani positively increased plant growth promotion activities like shoot and root length, fresh and dry weight of shoot and root, number of branches/plant, and induced accumulation of photosynthetic pigments like chlorophyll-a, b, and total carotenoids content during both seasons. Furthermore, under A. solani inoculated conditions, treatment with Tv+ F+ N (ST) + G+K (FS) significantly increased all yield attributing traits and other parameters associated with tuber nutritional quality such as starch (1.79-and 1.68-fold, respectively), vitamin-C (1.51-and 1.58-fold, respectively), total nitrogen (1.31-and 1.33-fold, respectively), total phosphorus (1.53-and 1.60-fold, respectively), and total potassium content (1.42-and 1.45-fold, respectively) as compared to untreated control in both seasons. So, it can be concluded that among all the treatments, integrated treatment comprising of tuber treatment with T. viride, flusilazole, and neem extract + one foliar spray of garlic extract and kasugamycin was found very effective in reducing early blight disease, promoting the plant’s growth, and increasing the yield as well as nutritional quality of tubers in the field conditions. The inclusive results indicated that integrated application might be a sustainable and eco-friendly control strategy for potato growers to manage potato early blight and achieve higher yields and nutritional tubers.

Condicionamento de sementes com qualidade de luz e extrato de Cyperus rotundus L. modula a germinação e o crescimento inicial de plântulas de Moringa oleifera

Improving plant germination is essential to guarantee better quality seedlings. Thus, this research aimed to evaluate whether the seed priming with light quality (LIQ) and the aqueous extract of Cyperus rotundus (AEC) tuber could modulate the germination and initial growth of Moringa oleifera L. seedlings. The experimental design was a completely randomized in the 4x4 factorial scheme, composed of four LIQ conditions (white, blue, red, and distant red light) and four AEC concentrations (0, 25, 50 and 100%). Seed priming with red light reduced the average emergence time, while blue, red, and extreme red lights associated with 50% of aqueous extract of C. rotundus increased shoot initial length and photosynthetic pigment accumulation. Seed priming with blue light resulted in seedlings with a shorter final shoot length. However, application of 100% of aqueous extract of C. rotundus reversed this. The white light in combination with concentrations of 50 and 100% of AEC promoted a higher relative shoot growth rate of seedlings. The research revealed that seed priming with light quality and aqueous extracts of C. rotundus tubers modulates the germination and initial growth of M. oleifera seedlings. More work needs to be done to determine the responsible compounds in AEC that is responsible for priming growth as phytohormones.

Impact of Colored Shade Nets on Biomass Production, Essential Oil Composition and Orientin and Isoorientin Content in Lippia gracilis Schauer.

The objective of this study was to evaluate the effect of ChromatiNet on vegetative growth, total antioxidant capacity, phenolic and essential oils (EOs) composition of Lippia gracilis. The plants were cultivated under full sunlight, black, blue and red ChromatiNet. The flavonoid content and antioxidant capacity were quantified spectrophotometrically. The C-glycosylflavone isomers (orientin and isoorientin) were isolated and identified by conventional spectroscopic techniques and measured using high-performance liquid chromatography-diode array detection. The EO was analysed by gas chromatography and gas chromatography-mass spectrometry. Environment influenced growth, total antioxidant capacity and phytochemical levels. Shoot dry weight, thymol, carvacrol and (E)-caryophyllene were favoured under red and black ChromatiNet. Root growth, EOs, caryophyllene oxide, p-cymene, flavonoids, orientin and isoorientin were favoured in sunlight. Growth and accumulation of EOs, flavonoids and photosynthetic pigments increased under blue ChromatiNet. Therefore, Lippia gracilis plants have plasticity related to the spectral quality of light and it cultivate depends of the phytochemicals of interest.

Изменчивость биохимических признаков Pinus sylvestris (Pinaceae) при адаптации форм в условиях избыточного увлажнения

Conifers are characterized by a certain degree of individual variability in the content of stress metabolites, which can be caused by genotypic variations or divergence in the growth conditions of individual trees. The purpose of the study is to evaluate the variation of biochemical traits of Scots pine, which are different in the color of male strobilus, during adaptation to the conditions of constant excessive moisture in the soil of the northern taiga. The dynamics of metabolic parameters of Pinus sylvestris L. were investigated in shrubsphagnum pine stands on marshy upland soils at the mouth of the Northern Dvina River (northern taiga subzone). From July to November 2018, needle samples from shoots were collected from 10 pine trees of each of the male strobilus types, differentiated by color. The contents of photosynthetic pigments, anthocyanins, ascorbic acid, proline, water-soluble proteins, and pH were measured under laboratory conditions. The synthesis of chlorophyll in the needles in the current year of formation decreased in trees of both forms during the dry summer period. A favorable temperature in the autumn period could promote an extension of photosynthetic pigment accumulation, which might negatively affect tree preparation for overwintering. There were no significant differences between f. erythranthera Sanio and f. sulfuranthera Kozubow in the needle content of chlorophyll and carotenoids, anthocyanins, ascorbic acid, free proline, water-soluble proteins, or pH. The similarities in the adaptation of the trees to the constant excessive soil moisture in northern taiga conditions were revealed. The seasonal factor had a considerable impact on the dynamics of biochemical parameters. Ascorbic acid, proline, and anthocyanin were more actively accumulated in the needles throughout the summer due to the high air temperature, resulting in an increase in antioxidant activity and the development of protective mechanisms aimed at reducing oxidative stress. The increase in water-soluble protein content in needles from October to November is one of the cryoprotective mechanisms of the trees for the winter period. Individual differences in ascorbic acid and proline contents in yellow microspore-bearing pine needles at the establishment of minus temperatures in November were considerably higher than in red microspore-bearing pine needles. This is regarded as the norm of the reaction for different types of trees to the influence of negative temperatures. For citation: Tarkhanov S.N., Pinaevskaya E.A., Aganina Y.E., Pakhov A.S. Variability of Biochemical Properties During Adaptation of Pinus sylvestris (Pinaceae) Forms to Excessive Moisture Conditions. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 4, pp. 58–75. (In Russ.). https://doi.org/10.37482/0536-1036-2023-4-58-75

Zinc oxide nano-flowers improve the growth and propagation of mulberry cuttings grown under different irrigation regimes by mitigating drought-related complications and enhancing zinc uptake

Silkworm larvae mainly consume mulberry leaves; therefore, mulberry cultivation is important for the production of raw silk. Drought stress and micronutrient deficiency (Zn) are known to affect the propagation of mulberry cuttings. In this purview, the current investigation attempted to inspect the efficacy of different concentrations of zinc oxide nano-flower (ZnNFs) applied through both soil admixture and foliar spray on the propagation of mulberry cuttings grown under deficit irrigation regimes. The overall results demonstrated that the ZnNF-treated plant cuttings were well-adapted to drought stress and performed better in comparison to the control set. Out of the tested concentrations – ZnNF-10 (applied as 10 mg/kg soil and 10 ppm as foliar spray thrice) was found to be optimum, showing relatively better initial root establishment, the emergence of leaves, and survival and sprouting percentage. Further studies also confirmed an improvement in the accumulation of photosynthetic pigments, carbohydrates, and protein content even under extreme drought conditions. Most importantly, the ZnNF-10 treatment contributed to ROS detoxification and cell membrane protection by enhancing the pool of antioxidant enzymes. The study further demonstrated that ZnNF-10 application enhanced zinc content by 147.50%, 179.49%, and 171.99% in root, shoot, and leaves of the treated cuttings; thereby, improving the bioaccumulation factor of the plant parts. All of these interactive phenomena led to an increment in shoot height, biomass, leaf area, and leaf number of cuttings. These findings, therefore, indicated that ZnNFs can be developed as a promising nano-fertilizer for mulberry growth facilitating Zn uptake and mitigation of drought-induced complications.

Extraction and comparative study of seasonal antioxidant activity using Nostoc species isolated from Gali Ali Bag, Erbil.

Seasonal variation of water, antioxidant activities as algal pigments, total antioxidant activities, DPPH, total phenolic compound using three solvents, methanol, acetone, and diethyl ether, of two algal species, N. commune and N. muscarum, were assessed. They also determined the physio-chemical and bacteriological water characteristics at the Gali Ali Bag. A significant variation were observed with an obvious correlation in water quality parameters in different seasons, generally raised in summer and reduced in winter. The two algal species show a higher accumulation of photosynthetic and accessory pigments in spring and summer and a significant decrease in winter. Antioxidant capacity in both algal species was analyzed by a three-way ANOVA and Kruskal-Wallis test. However, the contents were significant for all solvents. Moreover, N. muscarum shows the highest capacity in winter and reduced in summer for DPPH; however, the opposite pattern shows by N. commune. Although the total phenolic content of N. commune recorded a significant relation, N. muscarum was non-significant. The Cyanophyta algae show prominent growth responses and antioxidant activities and are better adapted to changing climatic conditions. Due to their prompt responses, even to minor changes in the aquatic environment, they can be used as ecological indicators in freshwater ecosystems.

The Yield and Quality Formation of Wheat Induced by Exogenous Strigolactones in Drought Condition

Drought is one of the major disasters affecting wheat. The change of wheat yield and quality directly affects the global population diet health. In this study, Strigolactones (SL) were sprayed on the leaf surface to study the relationship between wheat photosynthesis, nitrogen transport and yield and quality formation, further clarifying the influence of Sl on the synergic formation of yield and quality. The results showed that Sl could promote the accumulation of photosynthetic pigments in leaves, reduce nitrogen content in aging leaves and improve nitrogen transport level, then promote the improvement of grain yield and quality, so as to provide a reference for the application of Sl in wheat stress-resistant cultivation.

Salinity-induced modulation of growth and accumulation of phytochemicals composition in in vitro root cultures of Azadirachta indica

Salinity is a destructive abiotic factor that negatively impacts the growth and development of stress-intolerant plants. Although the effect of salinity on the growth of Azadirachta indica (neem) under in vitro conditions has been widely studied, little is known about the biochemical properties of in vitro root cultures exposed to salinity stress. Therefore, this study aimed to investigate the effects of varying concentrations of salinity on the biochemical properties of A. indica root cultures, specifically on total pigment and phenolic contents, antioxidant activities, and the presence of phytochemicals and azadirachtin compound, at different incubation periods. The results demonstrated that the root cultures coped with increasing NaCl concentrations by altering their phenotype. The highest antioxidant potential was observed in root cultures grown on MSN media (Murashige and Skoog media containing 3 mg L−1 NAA) supplemented with 0.5% w/v NaCl for 4 weeks. Additionally, this media composition and incubation period also resulted in the highest total phenolic and anthocyanin contents. The accumulation of photosynthetic pigments significantly decreased when exposed to NaCl treatments after 4 and 8 weeks. Interestingly, short-term exposure to NaCl had a positive impact on the azadirachtin (AZA) content, while longer treatment duration significantly decreased it. The highest amount of AZA was quantified from root cultures elicited with 1.5% w/v NaCl for 4 weeks. These findings contribute to a better understanding of the effects of salinity stress on the biochemical properties of in vitro root cultures of A. indica. The findings can aid in the development of strategies to enhance the production of bioactive compounds with potential applications in the food and pharmaceutical industries. Additionally, the study provides insights into the physiological mechanisms and manipulation of secondary metabolite production associated with salt tolerance in A. indica and other related species.

Magnesium oxide nanoparticles improved vegetative growth and enhanced productivity, biochemical potency and storage stability of harvested mustard seeds

A field study was conducted to investigate the influence of MgO-NPs priming on growth and development of mustard. Priming of mustard seeds before sowing with MgO-NPs at concentration 10, 50, 100, and 150 μg/ml enhanced the vegetative parameters of plants, with considerable increase in leaf area. MgO-NPs exposure increased the photosynthetic pigment accumulation in mustard that led to increase in biomass, carbohydrate content, and the yield in terms of total grain yield. Increased chlorophyll has simultaneously increased the oxidative stress in plants, and hence stimulated their antioxidant potential. A consistent increase was observed in the content of mustard polyphenols and activity of SOD, CAT, and APX on MgO-NPs exposure. MgO-NPs induced oxidative stress further reduced the protein content and bioavailability in mustard. We further, evaluated the influence of MgO-NPs on the quality of mustard harvested seeds. The seeds harvested from nanoprimed mustard possessed increased antioxidant potential and reduced oxidative stress. The carbohydrate and protein accumulation was significantly enhanced in response to nanopriming. Reduced chlorophyll content in seeds obtained from nanoprimed mustard indicated their potential for disease resistance and stability on long term storage. Therefore, the seeds harvested from MgO-NPs primed mustard were biochemically rich and more stable. Therefore, MgO-NPs priming can be potentially used as a novel strategy for growth promotion in plants where leaves are economically important and a strategy to enhance the seed quality under long term storage conditions.

Dynamics of accumulation of photosynthetic pigments in leaves <i>Trititrigia Cziczinii</i> Tzvel.

The productivity of plants depends on the efficiency of photosynthetic pigments, of which chlorophyll is the most important. In the conditions of sod-podzolic medium loamy soils of the Moscow region, the features of the accumulation of photosynthetic pigments (chlorophyll a and chlorophyll b) and the photosynthetic apparatus of a new synthetic grain crop Trititrigia cziczinii Tzvel. were studied. (Pamyati Lyubimovoj variety, line № 3202) compared to the winter wheat variety (Rubezhnaya) obtained by remote hybridization. The dynamics of the accumulation of chlorophyll a and chlorophyll b in the leaves of grain crops was measured during the generative development of plants starting from the earing phase (BBCH-scale code 52-53) on a spectrophotometer. The research results showed that all the studied varieties have their peaks of accumulation of the amount of chlorophyll a and chlorophyll b, depending on their biological characteristics. In winter wheat, the maximum amount of the sum of the two pigments fell on July 2 and amounted to 3,3 mg/g of raw leaf mass. In the trititrigia variety of the Pamyati lyubimovoj, the peak of pigment accumulation was noted almost a month later (July 30). The amount of pigments was 4,45 mg/g of raw mass. Trititrigia line № 3202 accumulated the maximum amount of chlorophyll (4,20 mg/g of raw leaf mass) even later than the Pamyati Lyubimovoj variety – August 5. The higher content of photosynthetic pigments in the cells of trititrigia leaves, compared with winter wheat, may indicate its high adaptive characteristics. And the peaks of chlorophyll accumulation, shifted by almost a month, indicate the long-term work of the assimilation apparatus and the uniqueness of the new synthetic culture. The leaf area measured in a straight linear way was different for all the studied objects. The largest leaf area was noted in the variety of trititrigia in Pamyati Lyubimovoj – 21,2 thousand m2/ha on July 13. The maximum leaf area at line № 3202 was 14.4 thousand m2/ha, then it gradually decreased. Rubezhnaya winter wheat had a significantly lower leaf area compared to trititrigia samples (the maximum was 6.1 thousand m2/ha), then the activity of the active assimilating surface decreased.

MtEIN2 affects nitrate uptake and accumulation of photosynthetic pigments under phosphate and nitrate deficiency in Medicago truncatula.

Ethylene (ET) controls many facets of plant growth and development under abiotic and biotic stresses. MtEIN2, as a critical element of the ET signalling pathway, is essential in biotic interactions. However, the role of MtEIN2 in responding to abiotic stress, such as combined nutrient deficiency, is less known. To assess the role of ethylene signalling in nutrient uptake, we manipulated nitrate (NO3 - ) and phosphate (Pi) availability for wild type (WT) and the ethylene-insensitive (MtEIN2-defective) mutant, sickle, in Medicago truncatula. We measured leaf biomass and photosynthetic pigments in WT and sickle to identify conditions leading to different responses in both genotypes. Under combined NO3 - and Pi deficiency, sickle plants had higher chlorophyll and carotenoid contents than WT plants. Under these conditions, nitrate content and gene expression levels of nitrate transporters were higher in the sickle mutant than in the WT. This led to the conclusion that MtEIN2 is associated with nitrate uptake and the content of photosynthetic pigments under combined Pi and NO3 - deficiency in M. truncatula. We conclude that ethylene perception plays a critical role in regulating the nutrient status of plants. This article is protected by copyright. All rights reserved.

Effects of Light-Emitting Diodes Light Quality on Growth, Development and Metabolism of Wheat (Triticum Aestivum L.) Seedlings

Light quality is considered crucial for plant growth, development and metabolism. The objective of this study was to investigate the impact of different light-emitting diodes (LEDs) light qualities on the growth of wheat (Triticum aestivum L.) seedlings. Five different set of LEDs light quality namely CK, 5R1B, 4R2B1G, 3B3R, 4B2R and 4B2R1G were used. The morphology, stomatal characteristic, biomass accumulation, RubisCO enzyme activity, photosynthetic pigment, value, soluble sugar and protein, Malondialdehyde (MDA ) root activity and others were measured with CK as the control. The results showed that the fresh weight, RubisCO enzyme activity, photosynthetic pigment accumulation, soluble sugar content and stomatal length in 5R1B treatment were higher than other treatment group, which increased by 1, 47, 57 and 18%, respectively compared to CK,. This indicated that 5R1B treatment group is most conducive to plant growth and photosynthesis, and does not cause lipid peroxidation damage to wheat seedlings under light treatment. Bangladesh J. Bot. 51(4): 987-993, 2022 (December) Special

Analysis of photosynthetic pigments pathway produced by CO2-toxicity-induced Scenedesmus obliquus

The coal-to-gas process produces carbon dioxide, which increases global warming, and its wastewater treatment generates sludge with high organic toxicity. Scenedesmus obliquus is a potential solution to such environmental problems, and photosynthetic pigments are the focus of this study. The optimal concentration of CO2 for the growth of Scenedesmus obliquus was found to be 30 % after increasing the concentration of CO2 (0.05 %–100 %). The accumulation of photosynthetic pigments during cultivation could reach 31.74 ± 1.33 mg/L, 11.21 ± 0.42 mg/L, and 5.59 ± 0.19 mg/L respectively, and the organic toxicity of sludge extract could be reduced by 44.97 %. Upregulation of A0A383VSL5, A0A383WMQ3, and A0A2Z4THB7 as photo systemic oxygen release proteins and propylene phosphate isomerase resulted in oxygen-evolving proteins in photosystem II, electron transport in photosystem I, and intermediates in carbon fixation. This is achieved by increasing the intracellular antennae protein and carbon fixation pathway, allowing Scenedesmus obliquus to both tolerate and fix CO2 and reduce the organic toxicity of sludge. These findings provide insights into the innovative strategy underlining the fixation of CO2, treatment and disposal of industrial residual sludge, and the enhancement of microalgal biomass production.

Transcriptome and Deletion Mutant Analyses Revealed that an RpoH Family Sigma Factor Is Essential for Photosystem Production in Roseateles depolymerans under Carbon Starvation.

Roseateles depolymerans is an obligately aerobic bacterium that produces a photosynthetic apparatus only under the scarcity of carbon substrates. We herein examined changes in the transcriptomes of R. depolymerans cells to clarify the expression of photosynthesis genes and their upstream regulatory factors under carbon starvation. Transcriptomes 0, 1, and 6‍ ‍h after the depletion of a carbon substrate indicated that transcripts showing the greatest variations (a 500-fold increase [6 h/0 h]) were light-harvesting proteins (PufA and PufB). Moreover, loci with more than 50-fold increases (6 h/0‍ ‍h) were fully related to the photosynthetic gene cluster. Among 13 sigma factor genes, the transcripts of a sigma 70 family sigma factor related to RpoH (SP70) increased along photosynthesis genes under starvation; therefore, a knockout experiment of SP70 was performed. ΔSP70 mutants were found to lack photosynthetic pigments (carotenoids and bacteriochlo-rophyll a) regardless of carbon starvation. We also examined the effects of heat stress on ΔSP70 mutants, and found that SP70 was also related to heat stress tolerance, similar to other RpoH sigma factors (while heat stress did not trigger photosystem production). The deficient accumulation of photosynthetic pigments and the heat stress tolerance of ΔSP70 mutants were both complemented by the introduction of an intact SP70 gene. Furthermore, the transcription of photosynthetic gene operons (puf, puh, and bch) was markedly reduced in the ΔSP70 mutant. The RpoH homologue SP70 was concluded to be a sigma factor that is essential for the transcription of photosynthetic gene operons in R. depolymerans.

STUDY OF THE EFFECT OF NEW 6-R-3,5-DINITRO-1,2,3,4-TETRAHYDROPYRIDINES ON THE ACCUMULATION OF PHOTOSYNTHETIC PIGMENTS AND ASCORBIC ACID IN PLANT TISSUES

Background. The problem of finding new effective plant protection products remains an urgent task of modern agrochemistry. It is known that tetrahydropyridine derivatives exhibit a broad spectrum of biological activity, including fungicidal activity. However, compounds with potential biological activity can also be highly toxic to humans, cultivated crops, and the environment as a whole, so it is necessary to study their environmental safety. The content of photosynthetic pigments and ascorbic acid are one of the most important biochemical indicators of plant response to environmental stress factors, therefore, determining their amount helps to assessthe physiological state of plants and analyze the toxicity of the synthesized compounds.
 Purpose. To study the effect of new 6-R-3,5-dinitro-1,2,3,4-tetrahydropyridines on the content of photosynthetic pigments and ascorbic acid in plant tissues in order to assess the safety of their use as potential plant protection products.
 Materials and methods. The test compounds were obtained by the previously developed method for the selective reduction of 2-R-3,5-dinitropyridines. Winter wheat seeds of the Moskovskaya 39 variety were germinated in Petri dishes using solutions of the synthesized substances. Seeds germinated in water were used as controls. On the ninth day, the content of various groups of photosynthetic pigments (chlorophylls a, b, carotenoids), as well as ascorbic acid in plant tissues was determined. All experiments were carried out in triplicate. In addition, the analytes were tested for toxicity using the GUSAR Environmental Toxicity software.
 Results. The effect of new derivatives of tetrahydropyridine on the accumulation of photosynthetic pigments and ascorbic acid in plant tissues of winter wheat was studied. It was shown that the studied compounds do not have a significant toxic effect on plants.
 Conclusion. As a result of studying the effect of new 6-R-3,5-dinitro-1,2,3,4-tetrahydropyridines on the content of photosynthetic pigments and ascorbic acid, as well as in silico computer prediction in GUSAR Environmental Toxicity, it was found that, in general, the studied compounds are relatively safe and, therefore, promising for further testing as biologically active plant protection products.