Photosynthetic Pigments Research Articles

The Effects of Disinfection Byproduct 2,6-Dichloro-1,4-benzoquinone on the Cyanobacterium Microcystis aeruginosa: From the Perspectives of Biochemistry and Non-Targeted Metabolomics

2,6-Dichloro-1,4-benzoquinone (2,6-DCBQ) is an emerging chlorinated disinfection byproduct (DBP) in bodies of water. However, this compound poses an unknown toxic effect on cyanobacteria. In this study, the toxicological mechanisms of 2,6-DCBQ in Microcystis aeruginosa (M. aeruginosa) were investigated through physiological and nontargeted metabolomic assessments. The results show that 2,6-DCBQ inhibited the growth of M. aeruginosa, reduced its photosynthetic pigment and protein contents, increased the levels of reactive oxygen species, damaged the antioxidant defense system, and aggravated the cytomembrane. Meanwhile, 2,6-DCBQ stimulated the production and release of microcystin-LR (MC-LR) and altered the transcripts of genes associated with its synthesis (mcyA, mcyD) and transport (mcyH). In addition, nontargeted metabolomics of M. aeruginosa cells exposed to 0.1 mg/L 2,6-DCBQ identified 208 differential metabolites belonging to 10 metabolic pathways and revealed the considerable interference caused by 2,6-DCBQ among ABC transporters, the two-component system, and folate biosynthesis. This study deepens the understanding of the physiological and nontargeted metabolomic responses of M. aeruginosa exposed to 2,6-DCBQ, offers insights into the toxic effect of 2,6-DCBQ on M. aeruginosa, and provides a theoretical basis for the ecological risk assessment of emerging DBPs in accordance with water quality criteria.

Multiple physiological response analyses of Chlorella vulgaris exposed to silver nanoparticles, ciprofloxacin, and their combination.

The combination of silver nanoparticles (AgNPs) and ciprofloxacin (CIP) can be considered an alternative to combat multidrug-resistant microbial infections. However, knowledge about their combined toxicity is scarce after being released in an aquatic environment. The present study evaluated the individual toxicity of AgNPs and CIP and their combined toxicity on the unicellular green microalga Chlorella vulgaris, evaluating cellular responses and conducting metabolomic analysis. The median effective concentrations at 96 h (EC50-96h) for AgNPs, CIP, and the mixture were 132 µg L-1, 7000 µg L-1, and 452 µg L-1, respectively. CIP exhibited a synergistic effect with AgNPs. The toxic ranking for C. vulgaris was AgNPs > AgNPs + CIP > CIP. The growth rate was the most evident parameter of toxicity. Cell diameter significantly increased (p < 0.001) at 96 hours for the highest concentrations tested of AgNPs, CIP, and the mixture, with increases of 24%, 41%, and 19%, respectively, compared to the control. Photosynthetic pigment analyses revealed that C. vulgaris upregulated chlorophyll, carotenoids, and pheophytin. Cell exposure to CIP caused an SOS response involving increased protein and carbohydrate concentrations to tolerate antibiotic stress. Exposure to AgNPs and CIP increased catalase and glutathione S-transferase activity, but the mixture decreased the activity. AgNPs increased malondialdehyde content in exposed cells due to fatty acid peroxidation. These pollutants revealed their potential risks in interfering with survival and metabolism. Our findings highlight the possible hazards of co-pollutants at environmentally relevant quantities, providing insights into the individual and combined ecotoxicity of AgNPs and CIP.

Cellular and biochemical alterations induced by diesel oil in the brown alga Sargassum cymosum var. stenophyllum cultured in vitro.

The effect of the in vitro acute exposure to diesel oil (0.001%, 0.01%, 0.1%, and 1%, v/v) has been evaluated in the brown seaweed Sargassum cymosum var. stenoplhyllum by determining the contents of photosynthetic pigments, phenolic compounds, and morphological and cellular changes. In vitro cultures of S. cymosum were exposed to diesel oil for 30min, 1h, 12h, and 24h under laboratory-controlled conditions. Chlorophyll a and c contents increased after diesel oil exposure as the amounts of carotenoids did not show a clear trend along the experimental period. However, a reduction in the concentration of phenolic compounds was detected by chemical analysis, a finding further corroborated by electron microscopy and cytochemical analyzes. The thickness of the cell wall showed to be augmented and the accumulation of phenolic compounds therein was also detected after exposure to that petroleum derivative. Besides, morphological analysis through scanning electron microscopy revealed irregularities in the cell surface, as transmission electronic microscopy indicated an increased number of vacuoles in the cells. Based on these results, it could be concluded that the acute exposure to diesel oil brings about a stress effect in S. cymosum var. stenophyllum, promoting alterations in the seaweed secondary metabolism, stimulating protective mechanisms against oxidative stress, and changing cell's morphological and ultrastructural traits.

Comparative Efficacy of Melatonin and Brassinolide in Mitigating the Adverse Effects of Cadmium on Wolffia arrhiza

Melatonin (MT) and brassinolide (BL) are phytohormones that regulate various physiological processes in plants. This study investigates their effects on Wolffia arrhiza when exposed to cadmium (Cd). Plant hormones were quantified using liquid chromatography-mass spectrometry, while photosynthetic pigments and phytochelatins (PCs) were analyzed through high-performance liquid chromatography. Protein, monosaccharide levels, and antioxidant activities were also spectrophotometrically measured. The findings reveal that MT and BL treatment decreased Cd accumulation in W. arrhiza compared to plants only exposed to Cd. MT was particularly effective in reversing Cd-induced growth inhibition and reducing stress markers more significantly than BL. It also enhanced antioxidant activity and maintained higher levels of photosynthetic pigments, proteins, and sugars. Although BL was less effective in these aspects, it promoted greater synthesis of glutathione and PCs in Cd-exposed duckweed. Overall, both MT and BL alleviate the negative impact of Cd on W. arrhiza, confirming their crucial role in supporting plant health under metal stress conditions.

Phytotoxic Effects of Polystyrene Microplastics on Growth Morphology, Photosynthesis, Gaseous Exchange and Oxidative Stress of Wheat Vary with Concentration and Shape

Microplastics pose a serious ecological threat to agricultural soils, as they are very persistent in nature. Microplastics can enter the soil system in different ways and present different shapes and concentrations. However, little is known about how plants react to microplastics with different concentrations and shapes. To this end, we conducted a factorial pot experiment with wheat (Triticum aestivum L.) in which we mixed polystyrene (PS) in different shapes (bead, fiber and powder) with soil at concentrations of 0, 1, 3 and 5%. Although all shapes of PS significantly reduced morphological growth traits, PS in powder shape was the microplastic that reduced plant height (by 58–60%), fresh biomass (by 54–55%) and dry biomass (by 61–62%) the most, especially at the 3% and 5% concentrations compared with 0% PS. Similar negative effects were also observed for root length and fresh root weight at the 3% and 5% concentrations, regardless of shape. A concentration-dependent reduction in the leaf area index (LAI) was also observed. Interestingly, increasing the PS concentration tended to up-regulate the activity of antioxidant enzymes for all shapes, indicating potential complexity and a highly time-dependent response related to various reactive oxygen species (ROS). Importantly, PS at the 5% concentration caused a significant reduction in chlorophyll pigmentation and photosynthetic rate. For the transpiration rate, stomatal conductance and intercellular CO2 concentration, the negative effects of PS on wheat plants increased with the increase in microplastic concentration for all shapes of PS. Overall, we concluded that PS microplastics at higher concentrations are potentially more devastating to the physiological growth and biochemical attributes of wheat, as evidenced by the negative effects on photosynthetic pigments and gas exchange parameters for all shapes. We recommend further research experiments not only on translocation but also on tissue-specific retention of different sizes in crops to fully understand their impact on food safety.

Influence of Divalent and Trivalent Sources of Iron on Growth, Iron Uptake-Transport and Photosynthetic Pigments in Rice (Oryza sativa L.) Cultivars During the Vegetative Stage

ABSTRACT Rice (Oryza sativa L.) is the most significant staple food globally. It can cultivate in a wide range of environments. Iron (Fe) deficiency is an important abiotic stress in crop production. To deal with Fe deficiency, plants have evolved mechanisms for Fe uptake. The study aims to examine the abilities of the cultivars – Biga İncisi, Osmancık-97, Hamzadere, Ronaldo, and Edirne – to utilize both non-chelated (FeSO4·7 H2O) and chelated forms (Fe(II)-EDTA and Fe(III)-EDTA) of Fe, which exist in divalent and trivalent states, along with their physiological responses to these different forms of Fe. All cultivars were grown in a sand culture under Fe-deficient (Fe:0) and -sufficient conditions (45 µM Fe). Roots of all rice cultivars grown under Fe deficiency conditions exhibited both phytosiderophore (PS) release and ferric chelate reductase (FCR) activity. These results indicate that all cultivars can employ a Combined Strategy (Strategy I/II) mechanism for Fe uptake. Nevertheless, the efficiency of rice plants in utilizing Strategy I and Strategy II mechanisms for Fe uptake varied depending on the cultivars. Hamzadere exhibited higher PS production, whereas Ronaldo displayed higher FCR activity. The application of divalent and trivalent Fe sources significantly increased the dry weight of shoots, Fe uptake by shoots and roots, and the pigment content of leaves in the rice cultivars. For other cultivars except Hamzadere and Edirne, the utilization rate of Fe(II)-EDTA was higher than that of Fe(III)-EDTA and FeSO4.7 H2O. The cultivar Osmancık-97 had the highest utilization rate (21.30%) of Fe(II)-EDTA.

Optimizing Growth Conditions and Biochemical Properties of Chondracanthus acicularis (Rhodophyta) in Laboratory Settings

This study aimed to evaluate the laboratory cultivation of Chondracanthus acicularis, focusing on key environmental parameters such as nutrient levels and light exposure. The results provide insights into the optimal growth conditions and biochemical composition of C. acicularis, which are crucial for its sustainable exploitation in industrial applications. Significant differences in the relative growth rate (RGR) and productivity (Y) were found between the different treatments. Seaweed grown on Provasoli (PES) Medium with white LED light and red LED light showed the best growth rates. Negative growth was observed in treatments with Nutribloom plus®, and blue LED light. The proximate composition analysis revealed a high moisture content across all treatments, with significant differences in ash and organic matter content between the treatments. The use of LED light played a crucial role in optimizing growth by influencing photosynthetic efficiency and pigment production. The proximate composition varied significantly between treatments, especially ash and organic matter. Light and nutrient conditions also influenced pigmentation and colour characteristics, with significant changes in phycoerythrin, phycocyanin, and chlorophyll concentration. PES treatments consistently showed the highest colour variation. These findings highlight the influence of environmental conditions on seaweed growth, productivity, pigmentation, and proximate composition, and provide valuable insights for optimized cultivation strategies.

Nano-Zinc Oxide Can Enhance the Tolerance of Apple Rootstock M9-T337 Seedlings to Saline Alkali Stress by Initiating a Variety of Physiological and Biochemical Pathways

Soil salinization severely restricts the growth and development of crops globally, especially in the northwest Loess Plateau, where apples constitute a pillar industry. Nanomaterials, leveraging their unique properties, can facilitate the transport of nutrients to crops, thereby enhancing plant growth and development under stress conditions. To investigate the effects of nano zinc oxide (ZnO NP) on the growth and physiological characteristics of apple self-rooted rootstock M9-T337 seedlings under saline alkali stress, one-year-old M9-T337 seedlings were used as experimental materials and ZnO NPs were used as donors for pot experiment. Six treatments were set up: CK (normal growth), SA (saline alkali stress,100 mmol/L NaCl + NaHCO3), T1 (saline alkali stress + 50 mg/L ZnO NPs), T2 (saline alkali stress + 100 mg/L ZnO NPs), T3 (saline alkali stress + 150 mg/L ZnO NPs) and T4 (saline alkali stress + 200 mg/L ZnO NPs). The results were found to show that saline alkali stress could significantly inhibit the growth and development of M9-T337 seedlings, reduce photosynthetic characteristics, and cause ion accumulation to trigger osmotic regulation system, endogenous hormone and antioxidant system imbalances. However, the biomass, plant height, stem diameter, total leaf area and leaf perimeter of M9-T337 seedlings were significantly increased after ZnO NP treatment. Specifically speaking, ZnO NPs can improve the photosynthetic capacity of M9-T337 by increasing the content of photosynthetic pigment, regulating photosynthetic intensity and chlorophyll fluorescence parameters. ZnO NPs can balance the osmotic adjustment system by increasing the contents of soluble protein (SP), soluble sugar (SS), proline (Pro) and starch, and can also enhance the activities of enzymatic (SOD, POD, and CAT) and non-enzymatic antioxidant enzymes (APX, AAO, GR, and MDHAR) to enhance the scavenging ability of reactive oxygen species (H2O2, O2•−), ultimately reducing oxidative damage; ZnO NPs promoted the growth of M9-T337 seedlings under saline alkali stress by synergistically responding to auxin (IAA), gibberellin (GA3), zeatin (ZT) and abscisic acid (ABA). Additionally, the Na+/K+ ratio was reduced by upregulating the expression of Na+ transporter genes (MdCAX5, MdCHX15, MdSOS1, and MdALT1) and downregulating the expression of K+ transporter genes (MdSKOR and MdNHX4). After comprehensive analysis of principal components and correlation, T3 (150 mg/L ZnO NPs) treatment possessed the best mitigation effect. In summary, 150 mg/L ZnO NPs(T3) can effectively maintain the hormone balance, osmotic balance and ion balance of plant cells by promoting the photosynthetic capacity of M9-T337 seedlings, and enhance the antioxidant defense mechanism, thereby improving the saline alkaline tolerance of M9-T337 seedlings.

Eustress responses of Musa acuminata cv. red banana using LED spectra.

This study examined the impacts of different LED spectra on the growth of in vitro cultures of Musa acuminata cv. red banana and their biochemical profile, including the antioxidant enzymes catalase and ascorbate peroxidase, photosynthetic pigment and accumulation of total carbohydrate content. The far-red LEDs significantly increase shoot elongation (10.04cm). The greatest number of shoots (2.97) and the greatest multiplication rate (80%) were obtained under the treatment with blue + red LEDs. The formation of microshoots were also enhanced by blue and white LED exposure in a range of 2-2.57 shoots per explant. Root formation was also stimulated by dichromatic blue + red (6.00) LED using MS medium with 2µM indole-3-butyric acid (IBA). The enzymes catalase and ascorbate peroxidase were significantly up-regulated by irradiation with far-red (0.11 ± 0.02 CAT, 0.18 ± 0.04 APX U/mg) and blue (0.08 ± 0.01CAT, 0.10 ± 0.01APX U/mg) LED light. Total chlorophyll (0.45 to 0.80mg/g) was elevated significantly by blue, blue + red and mint-white LED. On the other hand, carotenoids (12.08-14.61mg/g) were significantly boosted by blue + red, red and mint-white LED light. Meanwhile, porphyrin (294.10-350.57mg/g) was highly synthesised after irradiation with mint-white light. Irradiation with LED light significantly increased the accumulation of carbohydrates with the highest carbohydrate content under blue + red LED light (102.22 ± 2.46mg/g) and blue light (91.69 ± 2.10mg/g). In conclusion, these results confirm that the vegetative properties and biochemical profile of red banana in vitro are eustress response to LED spectra.

The Q-Band Energetics and Relaxation of Chlorophylls a and b as Revealed by Visible-to-Near Infrared Time-Resolved Absorption Spectroscopy.

Chlorophyll (Chl) is the most abundant light-harvesting pigment of oxygenic photosynthetic organisms; however, the Q-band energetics and relaxation dynamics remain unclear. In this work, we have applied femtosecond time-resolved (fs-TA) absorption spectroscopy in 430-1,700 nm to Chls a and b in diluted pyridine solutions under selective optical excitation within their Q-bands. The results revealed distinct near-infrared absorption features of the Bx,y ← Qy and Bx,y ← Qx transitions in 930-1,700 nm, which together with the steady-state absorption in 400-700 nm unveiled the Qx(0,0)-state energy that lies 1,000 ± 400 and 600 ± 400 cm-1 above the Qy(0,0)-state for Chls a and b, respectively. In addition, the Qx-to-Qy internal conversion time constants are estimated to be less than 80 fs for Chls a and b. These findings may shed light on understanding the roles of the Chls in the primary excitation energy transfer reactions of photosynthesis.

Effects of Enterobacter cloacae extract, selenium nanoparticles and methyl jasmonate on shoot liquid cultures of Sarcocornia fruticosa under salinity stress

BackgroundThe in vitro propagation of halophytes is innovative perspective for sustainable agriculture, conservation of natural plants and essential raw materials for industry due to increasing soil salinization and decreasing freshwater availability. Sarcocornia fruticosa, a halophytic plant, may hold promise for biosaline production systems and achieve bioactive products. Understanding the salt tolerance mechanisms of halophytes through elicitors can enhance the production of secondary metabolites, such as phenolics and flavonoids, under saline environment. This study aimed to evaluate the effects of NaCl salinity (700 mM and 1000 mM) on Sarcocornia fruticosa shoot cultures and assess the influence of different elicitors-Enterobacter cloacae extract (BE), selenium nanoparticles (SeNPs) and methyl jasmonate (MeJA) -on the plants growth, physiological and biochemical responses, and isorhamnetin production.MethodologyShoot cultures were grown under controlled conditions with two concentrations of NaCl, alone and in combination with BE (0.5%), SeNPs (100 ppm), or MeJA (50 µM). Growth parameters, photosynthetic pigments, ion accumulation, osmolyte content, oxidative stress marker, enzyme activity, phenolic compound levels, and isorhamnetin production were analyzed to determine the impact of salinity and elicitor treatments on S. fruticosa for 14 days.ResultsSarcorcocnia fruticosa exhibited better tolerance up to 700 mM than 1000 mM NaCl, as evidenced by higher dry weights, chlorophyll a/b ratios, and enhanced osmolyte and antioxidant contents. Elicitation both saline cultures with BE and SeNPs improved growth mostly by increasing biomass, pigment contents, K+/Na+ ratios, and reducing lipid peroxidation, however, MeJA reduced the biomass mainly by increasing MDA and Na+ ion accumulation. In contrast, application of all elicitors stimulated the production of phenolic compounds and isorhamnetin, as well as BE can contribute for increasing resistance of S. fruticosa to stressful conditions.ConclusionThis study demonstrated that PTC techniques and appropriate elicitors can optimize halophyte propagation and secondary metabolite production under saline conditions. The findings suggest that BE and SeNPs significantly enhanced the growth and biochemical resilience of S. fruticosa under salinity stress, with a notable increase in isorhamnetin production. MEJA.

A Comparative Study on Drought Stress Response In Vitro and In Vivo Propagated Fragaria vesca Plants

The evaluation of plant responses to water deficit in the substrate, particularly in the context of intensifying climate change, represents a critical factor for ensuring stable agricultural production, economic resilience, and food security. The primary objective of this study was to compare the physiological and biochemical responses to water deficit in conventional cultivation of Fragaria vesca plants propagated both in vitro and in vivo. The research encompassed measurements of gas exchange parameters, chlorophyll “a” fluorescence, photosynthetic pigment and proline content in leaves, leaf relative water content index, total fruit yield, single fruit weight, fresh and dry mass of the root system, as well as the concentrations of K, Ca, Mg, Na, Cu, Zn, Mn, and Mo. Additionally, the ratio of monovalent to divalent cations in leaves, roots, and crowns was analyzed. The results revealed significant differences between the experimental variants under optimal conditions and their respective responses to drought stress. Plants derived from in vitro cultures, despite exhibiting initially lower physiological trait values, demonstrated higher yield potential (no significant difference in the yield of fresh fruit mass compared to a 78% reduction). However, a long-term lack of water caused greater damage to their photosynthetic system—a reduction in physiological traits to 80% was observed, compared to a maximum decrease of 40% in plants derived from seedlings. The results highlight that environmental conditions and the acclimatization process of plants derived from in vitro cultures can significantly influence their adaptive potential and productivity.

A new mesophilic member of the Chloroflexota phylum 'Ca. Сhloroploca septentrionalis' from the meromictic lake Bol'shie Khruslomeny separated from the White Sea.

A new filamentous phototrophic bacterium Khr17 was isolated as an enrichment culture from the brackish polar lake Bol'shie Khruslomeny. The organism was a halotolerant, strictly anaerobic phototroph possessing photosystem II. Sulfide was required for phototrophic growth. The cells of bacterium Khr17 formed nonmotile, wavy trichomes surrounded by a sheath. The cells contained chlorosomes, gas vesicles, and storage granules. The antenna pigments of bacterium Khr17 were bacteriochlorophyll c and β- and γ-carotenes. The genome of Khr17 bacterium carries all the genes responsible for CO2 fixation via the 3-hydroxypropionate pathway. The genes encoding the proteins of the nitrogenase complex were not found. The DNA G+C content was 59.9%. The 16S rRNA gene sequence of isolate Khr17 exhibited 99.4% similarity to related species. The average nucleotide identity and digital DNA-DNA hybridization values for the isolate showed 91.9% and 46.9% similarity, respectively, to other 'Ca. Chloroploca' species. Based on its phenotypic and phylogenetic characteristics, classification of Khr17 as member of a new species, 'Ca. Chloroploca septentrionalis' sp. nov., was proposed. Members of the genus 'Ca. Chloroploca' have previously not been found in Arctic areas and in the plankton of meromictic lakes.

Clay-catalyzed ozonation of Norfloxacin - Effects of metal cation and degradation rate on aqueous media toxicity towards Lemna minor.

Norfloxacin was ozonized in aqueous montmorillonite suspensions and the resulting toxicity on Lemna minor was investigated for understanding the impact of natural partial oxidation of antibiotics on clay-containing ecosystems. Ion-exchanged montmorillonites (Mt) were used as catalysts because of their large occurrence in soils and aquatic media, while Lemna minor, an aquatic macrophyte is regarded as a bioindicator highly responsive to ecotoxicity change in the environment. NOF solutions exhibit intrinsic toxicity on L. minor expressed in terms of fresh mass, frond number, chlorophyll content and production of reactive oxygen species. This toxicity was found to trigger through oxidative stress and was enhanced by ozonation. UV-Vis spectrophotometry and liquid chromatography coupled to mass spectrometry (LC-MS) showed that the toxicity specifically evolves in time according to the clay exchangeable cations, oxidation advancement and derivatives distribution, and confirmed the unavoidable formation of hydroxylated and acidic intermediates. The cleavage of the phenyl and pyridinyl groups appear to occur even in non-catalytic ozonation and generate potentially more toxic derivatives than the parent molecule with excessive oxidative stress and changes in the distribution of the photosynthetic pigments. Addition of Fe(II)Mt and Cu(II)Mt induced a more effective ozonation with, but with much less toxicity with Fe2+ exchanged Mt catalyst. This research provides valuable insights into the environmental fate of antibiotics under aerobic conditions, and allows understanding their impact evolution on biodiversity, envisaging strategies targeting optimized water treatments with complete mineralization of organic pollutants.

Distinctive features of the dynamics of photosynthetic pigment contents and the number of cultivated endophytic bacteria forms in Ribes nigrum L. leaves

The article presents the results of studying the dynamics of photosynthetic pigment contents and the number of cultivated endophytic bacteria (EB) forms in leaves of cultivars of different genetic origin bred by FSBSO ARHCBAN. The research was conducted in 2021-2024 on the blackcurrant (Ribes nigrum L.) collection plantings of the Kokinsky experimental station (Bryansk Oblast) and the research department of the gene pool and bioresources (Stupinsky District, Moscow Oblast) of the FSBSO ARHCBAN. The cultivars included Barmaley, Bryansky Agat, Gamayun, Debryansk, Mif. Weather conditions during the growing season were found to have a signifi cant effect on the content of cultivated EB forms in leaves. On average, over the four-year research period, Bryansky Agat was determined to have the largest number of EB, i. e., up to 107,823 CFU/g. The cultivar was characterized by the most stable abundance indicators of cultivated EB forms in leaves. The blackcurrant cultivars Barmaley and Bryansky Agat were the most responsive to this indicator. The number of cultivated EB forms in their leaves predictably positively correlated with the number of sunny days, as well as with average values of daytime and nighttime temperatures in spring and fall. Except for Mif, all cultivars responded negatively or weakly to the amount of precipitation and daily mean temperature. The Debryansk cultivar was found to be the most unresponsive to weather factors, which may be associated with the lowest annual average number of cultivated EB forms in its leaves (70,713 CFU/g). The high content of cultivated EB forms and chlorophyll a in Bryansky Agat leaves may indicate a possible role of endophytic bacteria in stimulating the synthesis of photosynthetic pigments in blackcurrant leaves.

Zinc oxide nanoparticles foliar use and arbuscular mycorrhiza inoculation retrieved salinity tolerance in Dracocephalum moldavica L. by modulating growth responses and essential oil constituents

The production of medicinal plants under stressful environments offers an alternative to meet the requirements of sustainable agriculture. The action of mycorrhizal fungus; Funneliformis mosseae and zinc in stimulating growth and stress tolerance in medicinal plants is an intriguing area of research. The current study evaluated the combined use of nano-zinc and mycorrhizal fungus on the physiochemical responses of Dracocephalum moldavica under salinity stress. The study employed a factorial based on a completely randomized design with three replications. The treatments were different levels of salinity (0, 50, and 100 mM NaCl), two levels of mycorrhiza application (0 and 5 g kg− 1 of soil), and two levels of foliar spraying of nano zinc oxide (0 and 1000 ppm). Salinity decreased the photosynthetic pigments content, SPAD value, and chlorophyll fluorescence data (Fm, Fv, Fv/Fm). Plant dry weight, Na+ content, and essential oil content were significantly higher at 50 mM salinity + co-application of mycorrhiza and nano zinc oxide. Electrolyte leakage increased under salt stress, while mycorrhizal inoculation compensated for the trait. The main essential oil constituents were geranyl acetate, nerol, geranial, geraniol, viridiflorol, hexadecane, humulene, and germacrene D. Energy metabolism demonstrates the effectiveness of treatment combinations in promoting the biosynthesis and accumulation of essential oil components. The overall results with more comprehensive field-based studies would be advisable for the extension section to utilize marginal salty lands for the reliable production of a valuable medicinal plant.

Aplicação exógena de melatonina mitiga o estresse salino em soja

ABSTRACT Salinity is an abiotic factor that impairs the growth and physiological, biochemical, and molecular mechanisms of plants. Among plants, soybeans are an important crop worldwide, so managing abiotic factors is essential to mitigate plant damage. However, biostimulants, such as melatonin, are being employed to alleviate the stress caused by these factors. Therefore, this study aimed to evaluate the growth, photosynthetic pigments, and water relations of soybean plants subjected to salinity levels and exogenous melatonin application. The research was conducted in experimental area belonging to the Federal Rural University of the Semi-Arid Region, Mossoró, RN, Brazil. The experimental design was randomized blocks, arranged in a 3 x 3 factorial scheme (three salinity levels in the irrigation water - 0.50, 3.00, and 5.00 dS m-1 and three melatonin concentrations - 0, 0.5, and 1 mM) with three replications. At 47 days after planting, plant height, stem diameter, number of leaves, root length, chlorophyll content (a, b, and total), relative water content, leaf moisture, and electrolyte leakage were evaluated. Soybean plants tolerated the effects of salinity on growth aspects, photosynthetic pigments, and water relations up to 3.00 dS m-1, regardless of melatonin concentration. Exogenous application of melatonin mitigated the effects of salt stress on chlorophyll b and relative water content at salinity level of 5.00 dS m-1 and concentration of 1 mM.

Individual and interactive effects of temperature and blue light on canola growth, lignin biosynthesis and methane emissions.

It is now well documented that plants produce methane (CH4) under aerobic conditions. However, the mechanisms of methane production in plants, its potential precursors, and the factors that are involved in the process are not fully understood. Few studies have considered the effects of blue light on methane emissions from plants; however, the combined effects of temperature and blue light have not been studied. We studied the effects of two temperature regimes (22/18°C and 28/24°C; 16h light/8h dark), and three blue light levels (0, 4, and 8mWcm-2; 400-500nm) on the growth, lignin, and methane emissions of canola (Brassica napus). Plants were grown under experimental conditions for three weeks, and then methane, monolignols and other plant traits, including growth, biomass, growth index, photosynthesis, chlorophyll fluorescence, and photosynthetic pigments, were measured. Blue light significantly increased methane emissions, stem height, and growth rate, but decreased stem diameter, leaf number and area, biomass, specific leaf mass, leaf area ratio, shoot/root mass ratio, photosynthetic pigments, sinapyl alcohol, and coniferyl aldehyde. Higher temperature significantly decreased stem diameter, non-photochemical quenching, sinapyl alcohol, and coniferyl aldehyde. Methane emission was negatively correlated with plant dry mass, leaf area per plant, and maximum quantum yield of photosystem II. However, no significant relationships were found between methane and monolignols. In conclusion, plants emitted more methane under stress conditions; however, further studies are required to understand the potential precursors of methane and the mechanism of its synthesis in plants.

Harnessing Nature's Palette: Exploring Photosynthetic Pigments for Sustainable Biotechnology.

Photosynthetic microorganisms such as cyanobacteria, microalgae, and anoxygenic phototrophic bacteria (APB) have emerged as sustainable and economic biotechnology platforms due to their ability to transform energy from light into chemicals through photosynthesis. The light is absorbed by photosynthetic pigment-protein antenna complexes which are composed of pigments such as bacteriochlorophylls (BChl) and carotenoids in APB, and chlorophylls (Chl), phycobiliproteins (PBP), and carotenoids in cyanobacteria and microalgae. These photosynthetic pigments are essential in the physiology of photosynthetic microorganisms and offer significant health benefits due to their potent antioxidant activity, with properties that include anticancer, antiaging, antiproliferative, anti-inflammatory, and neuroprotective effects. This review first provides an overview of current advances in photosynthetic pigment synthesis and the latest strategies to increase pigment content in cyanobacteria, microalgae, and APB. It then delves into the pigment production process, covering biosynthetic pathways, critical environmental parameters, and extraction methods. Finally, the potential marketability of photosynthetic pigments together with current limitations are discussed.

Biochar for ameliorating soil fertility and microbial diversity: From production to action of the black gold.

This article evaluated different production strategies, characteristics, and applications of biochar for ameliorating soil fertility and microbial diversity. The biochar production techniques are evolving, indicating that newer methods (including hydrothermal and retort carbonization) operate with minimum temperatures, yet resulting in high yields with significant improvements in different properties, including heating value, oxygen functionality, and carbon content, compared to the traditional methods. It has been found that the temperature, feedstock type, and moisture content play critical roles in the fabrication process. The alkaline nature of biochar is attributed to surface functional groups and addresses soil acidity issues. The porous structure and oxygen-containing functional groups contribute to soil microbial adhesion, affecting soil health and nutrient availability, improving plant root morphology, photosynthetic pigments, enzyme activities, and growth even under salinity stress conditions. The review underscores the potential of biochar to address diverse agricultural challenges, emphasizing the need for further research and application-specific considerations.