Pigment Composition Research Articles

Long-term changes in phytoplankton pigment contents in the Baltic Sea: Trends and spatial variability during 20 years of investigations

The changes in phytoplankton pigment compositions and concentrations during a 20-year period of exploration of the Baltic Sea have been analysed. Both chlorophylls and carotenoids are characterized in the context of their monthly variations in the Gulf of Gdańsk and the open waters of southern Baltic Sea. It is assumed that pigment compositions are good markers of environmental changes, especially in the context of phytoplankton composition and biomass growth. Long-term trends and changes for both regions are established on the basis of marker pigment analyses for a period of two decades (1999–2018). Chlorophyll a, a marker of phytoplankton biomass, is clearly decreasing in both regions: −2.11% yr−1 (slope of trend curve −0.21) in the Gulf of Gdańsk and −2.41% yr−1 (slope −0.08) in the southern Baltic. Decreasing trends for several marker pigments have also been noted in both regions for the period in question, namely, fucoxanthin (diatom marker): −0.10% yr−1 in the Gulf of Gdańsk and the southern Baltic (respective slopes −0.0012 and −0.0003); alloxanthin (cryptophyte marker): −2.28% yr−1 (slope −0.012) in the Gulf of Gdańsk and −0.54% yr−1 (slope −0.001) in the southern Baltic; peridinin (dinoflagellate marker): −4.35% yr−1 (slope −0.05) in the Gulf of Gdańsk and −5.55% yr−1 (slope −0.02) in the southern Baltic. The decreases in the average concentrations of chlorophyll b (−1.30% yr−1, slope −0.008) and neoxanthin (−1.37% yr−1, slope −0.0014) have been slower in the Gulf of Gdańsk than in the southern Baltic (−3.31% yr−1, slope −0.013, and −3.38% yr−1, slope −0.0019 – respectively). In contrast, the yearly mean concentrations of zeaxanthin (the main cyanobacteria carotenoid) have increased significantly, to 7.16% yr−1 (slope 0.016) in the Gulf of Gdańsk and 1.45% yr−1 (slope 0.0022) in the southern Baltic. This may be the consequence of the reduced riverine supply of nutrients to these regions in recent years. The results indicate that the ecosystem of the Gulf of Gdańsk is responding more dynamically to eutrophication-related changes than the open waters of the southern Baltic Sea.

Brownification reduces oxygen gross primary production and community respiration and changes the phytoplankton community composition: An in situ mesocosm experiment with high‐frequency sensor measurements in a North Atlantic bay

AbstractIn recent decades, the increase in terrestrial inputs to freshwater and coastal ecosystems, especially occurring at northern latitudes, has led to a process of water color darkening known as “brownification.” To assess how brownification affects plankton community composition and functioning in northern coastal areas, an in situ mesocosm experiment using a highly colored humic substance to simulate a brownification event was performed in a North Atlantic bay (Hopavågen, Norway) in August 2019. Manual sampling for analyses of nutrient concentrations, phytoplankton pigments and zooplankton abundances was combined with high‐frequency (every 15 min) monitoring of key environmental variables to investigate the response of the plankton community in terms of oxygen metabolism and community composition. In response to brownification, the oxygen gross primary production (GPP) and community respiration (R) slowed down significantly, by almost one‐third. However, GPP and R both decreased to the same extent; thus, the oxygen metabolic balance was not affected. Moreover, the chlorophyll‐a concentration significantly decreased under brownification, by 9% on average, and the chemotaxonomic pigment composition of the phytoplankton changed, indicating their acclimation to the reduced light availability. In addition, brownification seemed to favor appendicularians, the dominant mesozooplankton group in the mesocosms, which potentially contributed to lowering the phytoplankton biomass. In conclusion, the results of this in situ mesocosm experiment suggest that brownification could induce significant changes in phytoplankton and zooplankton community composition and significantly alter the overall oxygen metabolism of plankton communities in a northern Atlantic bay.

Community metabolomics provides insights into mechanisms of pollution-induced community tolerance of periphyton

Chemical pollution is a major concern for freshwater ecosystems, but the impact and mechanisms of chemical stressors on communities are barely understood. Pollution stress beyond natural homeostatic capacities can trigger succession of tolerant species within a community, enhancing the overall community tolerance. This process was operationalized in the Pollution-Induced Community Tolerance (PICT) concept and applied in many case studies, however, the molecular mechanisms of community tolerance and implications for ecological functions remain largely unexplored. Our study aimed to demonstrate that 1) community metabolomics can unravel potential mechanisms of PICT in periphyton and 2) induced tolerance helps to maintain primary production under re-occuring pollution. To this end, we grew periphyton for 5 weeks with and without the model herbicide diuron in microcosms, quantified PICT, and determined the related metabolic fingerprint of periphyton by GC–MS-based untargeted metabolomics. Further, we explored the autotrophic community based on pigment composition and functional parameters including photosynthesis and gross primary production. Chronic diuron exposure resulted in a shift in pigment composition, higher community tolerance and an individual metabolic fingerprint in the contaminated communities. Opposing responses of selected metabolites during a short-term exposure indicated differences in diuron pre-adaptation in the different communities. Metabolites (threonic acid and two sugar acid lactones) were found to be related to tolerance development, suggesting that ascorbate metabolism was induced in contaminated communities. Despite these compensating mechanism, contaminated communities were compromised in production-to-respiration ratio and biomass. A ranking of sensitivity thresholds of different biological endpoints revealed that metabolites were less sensitive than photosynthetic parameters, which reflects the mode-of-action of the herbicide. In conclusion, we could demonstrate that community metabolomics is able to unravel complex biochemical changes and allows mechanistic insights into community tolerance. Moreover, we were able to show that induced community tolerance was insufficient to safeguard functions like primary production.

High near-infrared reflectance Bi2O3–ZnO–CaO yellow pigment system

A novel, eco-friendly yellow mixed oxide inorganic pigment composed of Bi2O3–ZnO–CaO was successfully synthesized using a solid-state reaction. The pigment color was light yellow and rare earth-free. The pigment composition was analyzed by X-ray diffraction (XRD), and the morphology and particle size were analyzed by scanning electron microscopy (SEM). Synthetic pigment samples had superior near-infrared (NIR) solar reflectance (84.2%–91.2%), and the NIR solar reflectance of the pigment-coated Al sheets was more than 50%. The powder samples added to frit glaze improves glaze reflectance.The thermal shielding performance was evaluated by simulating the pigment as a roofing material, and the results indicated that the pigment had an excellent thermal insulation effect. In addition, the pigment had good chemical stability. Therefore, the pigment can be used as a NIR reflection pigment in building coatings to achieve energy-savings by cooling surfaces.

Functional Stability of a Coastal Mediterranean Plankton Community During an Experimental Marine Heatwave

As heatwaves are expected to increase in frequency and intensity in the Mediterranean Sea due to global warming, we conducted an in situ mesocosm experiment for 20 days during the late spring and early summer of 2019 in a coastal Mediterranean lagoon to investigate the effects of heatwaves on the composition and function of coastal plankton communities. A heatwave was simulated by elevating the water temperature of three mesocosms to +3°C while three control mesocosms had natural lagoon water temperature, for 10 days. Further, the heating procedure was halted for 10 days to study the resilience and recovery of the system. Automated high frequency monitoring of dissolved oxygen concentration and saturation, chlorophyll-a fluorescence, photosynthetic active radiation, salinity, and water temperature was completed with manual sampling for nutrient and phytoplankton pigment analyses. High-frequency data were used to estimate different functional processes: gross primary production (GPP), community respiration (R), and phytoplankton growth (μ), and loss (l) rates. Ecosystem stability was assessed by calculating resistance, resilience, recovery, and temporal stability in terms of the key functions (GPP, R, μ, and l). Meanwhile, the composition of phytoplankton functional types (PFT) was assessed through chemotaxonomic pigment composition. During the heatwave, GPP, R, μ, and l increased by 31, 49, 16, and 21%, respectively, compared to the control treatment. These positive effects persisted several days after the offset of the heatwave, resulting in low resilience in these key functions. However, GPP and R recovered almost completely at the end of the experiment, suggesting that the effect of the heatwave on these two rates was reversible. The heatwave also affected the PFT composition, as diatoms, prymnesiophytes, and cyanobacteria were favored, whereas dinoflagellates were negatively affected. By highlighting important effects of a simulated marine heatwave on the metabolism and functioning of a coastal Mediterranean plankton community, this study points out the importance to extend this type of experiments to different sites and conditions to improve our understanding of the impacts of this climate-change related stressor that will grow in frequency and intensity in the future.

Carotenogenesis in <i>Haematococcus pluvialis</i> cells under the combined action of excess of NaCl in the culture medium and high light intensity

The parameters of growth and development of the microalga Haematococcus pluvialis, as well as the process of carotenogenesis, including the pigment composition and expression of the key genes of astaxanthin biosynthesis, were studied in algal cells under the combined action of excess of NaCl in the culture medium and high light intensity. It was found that the combination of excess of NaCl in the culture medium for Haematococcus pluvialis, initiated at the resting stage of the microalga, and high light intensity is not an effective method for induction of the accumulation of astaxanthin in the cells of Haematococcus pluvialis. A decrease in the level of expression of one of the key genes of carotenogenesis - phytoene synthase gene, was revealed under such conditions. At the same time, it was found that the combined action of high light intensity and excess of NaCl led to an increase in the ratio of astaxanthin cis-isomers, which are more biotechnologically valuable, in the total pigment pool.

Protochlorophylls in Cucurbitaceae – Distribution, biosynthesis and phylogeny

Using high-resolution chromatography we resolved monovinyl (MV)- and divinyl (DV)-protochlorophylls (Pchls) and detected all of their side-chain homologues in the inner seed coat of Cucurbita maxima, C. pepo and their varieties. Furthermore, we analyzed other less common representatives of the Cucurbitaceae family that were found to accumulate mostly MV-Pchls. All these species and varieties showed the characteristic composition of individual Pchls. Additionally, we also detected all of the corresponding protopheophytins, which accounted for between 1.1 and 35.5% of Pchls and are supposed to be degradation products of Pchls, formed during seed storage. A pigment composition analysis of C. maxima seedlings performed during deetiolation revealed that chlorophyll (Chl) a content increased gradually, while the levels of Pchl-GG and Chl-GG, a precursor of Chl a, were low and did not change significantly. However, when the seedlings were incubated with the precursor of tetrapyrrole biosynthesis (δ-aminolevulinic acid) before illumination, the Chl-GG content increased dramatically, while synthesis of Chl a was inhibited. These data indicate that in C. maxima seedlings, Chl a is not synthesized from geranylgeranyl-pyrophoshate via Chl-GG, but rather directly from phytyl-pyrophosphate. Phylogenetic analysis of Chl synthase genes revealed that many species, including those of the Cucurbitaceae family, have two or more Chl synthase genes. This suggests that these additional genes, at least in some species, might encode isoforms involved in Pchl synthesis.

Pigment Composition of Nine Brown Algae from the Iberian Northwestern Coastline: Influence of the Extraction Solvent.

Brown algae are ubiquitously distributed in the NW coastline of the Iberian Peninsula, where they stand as an underexploited resource. In this study, five solvents were applied to the extraction of pigments from nine brown algae, followed by their determination and quantification by HPLC-DAD. A total of 13 compounds were detected: Six were identified as chlorophylls, six were classified as xanthophylls, and one compound was reported as a carotene. Fucoxanthin was reported in all extracts, which is the most prominent pigment of these algae. Among them, L. saccharina and U. pinnatifida present the highest concentration of fucoxanthin (4.5–4.7 mg∙g−1 dry weight). Ethanol and acetone were revealed as the most efficient solvents for the extraction of pigments, showing a maximal value of 11.9 mg of total pigments per gram of dry alga obtained from the ethanolic extracts of H. elongata, followed by the acetonic extracts of L. ochroleuca. Indeed, ethanol was also revealed as the most efficient solvent according to its high extraction yield along all species evaluated. Our results supply insights into the pigment composition of brown algae, opening new perspectives on their commercial exploitation by food, pharmaceutical, and cosmeceutical industries.

Relationship among light intensity, pigment compositions and photoinhibition in relation to rhodoxanthin accumulation in the gymnosperm Cryptomeria japonica

ABSTRACT Some gymnosperms, including Cryptomeria japonica, exhibit needle reddening caused by red xanthophyll pigment, rhodoxanthin accumulation during long-term cold acclimation. Although photoprotective role of rhodoxanthin, serves as a “sunscreen”, was proposed, the key environmental and/or physiological factors involved in rhodoxanthin accumulation remain unclear. We exposed C. japonica trees to four different light intensities (13%, 39%, 64% and 100% of full sunlight) and measured some parameters (the nocturnal de-epoxidation state [DPS: ratio of the zeaxanthin + antheraxanthin to xanthophyll cycle pigments], the β-carotene level and the maximum photosystem II efficiency [Fv/Fm]) that have been suggested to play roles in rhodoxanthin accumulation. Rhodoxanthin was synthesised from autumn to winter, and less so in spring. Light intensity related to the maximum value of rhodoxanthin on chlorophyll (Chl) basis, but not to that on FW basis, because Chl content decreased with increasing light intensity. These results indicated that rhodoxanthin accumulation was accompanied with Chl decrease. In addition, the relationship between the rhodoxanthin content and the seasonal growth temperature was different among light treatments, reflecting differences in the amount of excess light among light treatments Furthermore, the rhodoxanthin content correlated significantly with the Fv/Fm, nocturnal DPS and β-carotene level in winter. Thus, rhodoxanthin accumulates in a photoinhibitory environment occurs with a decrease in Chl content and an increase in DPS.

THE COMPARISON OF PHOTOSYNTHESIS PARAMEATERS OF DIFFERENT WHEAT (TRITICUM AESTIVUM L.) VARIETIES

Field experiments were carried out at the Experimental Station of Vytautas Magnus University Agriculture Academy in Lithuania (54° 53' 3.26", 23° 50' 33.25") during 2017-2018. Six winter wheat varieties were studied in the experiment: 'Skagen' (control), 'Julius', 'Edvins', 'Artist', 'Aron' and 'Evina', which were sown on September 15. Preceding crop – winter rape. Seed rate – 4.5 million ha-1. The aspects of the dynamics of photosynthesis pigments in winter wheat leaves depending on variety is analysed in the article. Physiological activity of the plant, the growth and development are the most important moments decisive the accumulation of these pigments in the plant. Thus, the general condition of the plant might be described by the composition and content of photosynthesis pigments chlorophyll a, b and carotenoids. Spectrophotometric Wettstein method and “Genesys” 6 spectrophotometer were used for determination of the content of photosynthesis pigments (chlorophyll a, b and carotenoids) in green leaf mass in 96 % ethyl alcohol extract. The accumulated amounts of photosynthetic pigments (chlorophylls a, b and carotenoids) in different varieties of winter wheat leaves differed. Winter wheat variety 'Aron' accumulated the highest contents of photosynthetic pigments during the tillering and stem elongation stages, meanwhile during the heading – anthesis and early milky maturity stages winter wheat varieties 'Artist' and 'Skagen' demonstrated the best results. The LAI of different varieties of winter wheat differed in the field experiment. Significantly higher LAI was defined for winter wheat variety Artist (0.9) after the resumption of vegetation (BBCH 24–27) and for 'Skagen' (4.0) at the end of vegetation (BBCH 70–73). The highest LAI of winter wheat is determined during the heading - anthesis stage (varieties 'Aron', 'Edvins', 'Skagen'). During the growing season, the lowest LAI was observed for winter wheat variety 'Evina'.

Spectral Changes by Dye Sensitized Solar Modules Influence the Pigment Composition and Productivity of Arthrospira maxima and Increase the Overall Energy Efficiency

AbstractThe integration of semi‐transparent photovoltaics (PVs) with photobioreactors (PBRs) is a promising strategy to increase photoconversion efficiency, ensuring simultaneous electricity and algal biomass production. In this study, Arthrospira maxima is cultivated in an integrated system with a dye‐sensitized solar module (DSSM) to the front of the PBR to assess the possible advantages for biomass and phycocyanin production. The application of the DSSM does not influence biomass production, with the remarkable advantage of producing additional electric energy. However, an acclimation of pigment is observed, as DSSM causes a change in the transmitted light spectrum. Further experiments are conducted to investigate the effect of light quality using monochromatic light‐emitting diodes (LEDs) as controls. Phycocyanin‐targeted wavelengths exhibit a major impact on biomass growth and pigment productivity: low intensity enhanced process efficiency, suggesting that low light is preferable to enhance culture performance with respect to white light. The application of third‐generation PVs is only potentially advantageous if the transmission spectra of the module color and its aperture area are carefully designed. The application of monochromatic LEDs on PBRs also highlights the importance of properly managing the operative conditions to avoid energy losses.

New insight into the pigment composition and molecular mechanism of flower coloration in tulip (Tulipa gesneriana L.) cultivars with various petal colors

Pigmentation of various components leads to different colors in tulip flowers. To understand the molecular basis of the petal coloration in tulip, integrative analyses of the pigment components and transcriptome profiles were conducted on four tulip cultivars with different petal colors. A total of four major anthocyanins and 46 carotenoids were identified. The anthocyanin cyanidin 3-O-galactoside showed markedly higher abundances in the B cultivar than in the other varieties, and among the 46 kinds of carotenoids, (E/Z)-phytoene, violaxanthin myristate and violaxanthin palmitate were the major components. The RNA-seq and qRT-PCR results indicated that the pigment accumulation was linked to the expression of genes involved in the anthocyanin and carotenoid biosynthesis pathways. Yeast two-hybrid (Y2H) assays showed the interaction between different regulator factors in tulip MYB-bHLH-WD40 (MBW) complexes. Co-expression analyses of genes were performed, which include anthocyanin and carotenoid biosynthesis genes and transcription factors involved in MYB, bHLH, WRKY, AUX-IAA and MADS-box. The co-expression network and related analysis provide a basis for the discovery of color regulatory factors. Taken together, our study sheds light on the anthocyanin and carotenoid synthesis pathways and candidate regulatory transcription factors underlying flower coloration and shows the potential of flower breeding or pigments engineering in tulips.

Influence of pigment and binder composition on the dynamic water penetration and dried structure of precoating layers for double-coated paper

Influence of pigment and binder composition on the dynamic water penetration and dried structure of precoating layers for double-coated paper

Composition analysis of white mineral pigment based on convolutional neural network and Raman spectrum

AbstractExploiting portable Raman equipment to analyze the composition of mineral pigments has the advantages of convenience and speed. However, this method is more susceptible to ambient light, so it is necessary to develop an effective Raman spectrum identification method. Several studies have recently employed machine learning algorithms to automatically identify the Raman spectra of pigments and have revealed appealing results. Hence, in this paper, we propose a deep convolutional neural network that exploits portable Raman equipment to identify the components of white mineral pigments. Compared with classic methods, our technique achieved a higher matching rate of up to 98.7%. The experimental results show that the proposed method can analyze the composition of white mineral pigments in a real‐time, nondestructive, and accurate manner without requiring pretreatment of the spectra. We believe that our proposed method will be an essential tool for the detection of pigment components in archeological sites.

Modeling surface ocean phytoplankton pigments from hyperspectral remote sensing reflectance on global scales

Phytoplankton community composition impacts food webs, climate, and fisheries on regional and global scales, and can be assessed at coarse taxonomic resolution from biomarker pigments measured using high-performance liquid chromatography (HPLC). Presently, satellite ocean color provides unprecedented coverage of the global surface ocean and offers reliable estimates of bulk biological properties; however, existing multispectral sensors have limited ability to provide information about phytoplankton community composition. Satellite ocean color at hyperspectral resolution (e.g., NASA's upcoming Plankton, Aerosol, Cloud, and ocean Ecosystem sensor, PACE) is expected to improve estimates of phytoplankton community composition from space. Phytoplankton impact ocean color via contributions to absorption and fluorescence (through phytoplankton pigments) and scattering, especially on narrow spectral scales (5–100 nm). Here, a global open ocean dataset of concurrent HPLC pigments and hyperspectral remote sensing reflectance (Rrs(λ)) observations is used to model phytoplankton pigment composition from optical data. Phytoplankton pigments are reconstructed from Rrs(λ) using optimized principal components regression modeling. This work demonstrates that thirteen phytoplankton pigments, representing five phytoplankton pigment groups (e.g., diatoms, dinoflagellates, haptophytes, green algae, and cyanobacteria), can be modeled from hyperspectral Rrs(λ). Spectral information needed to model each phytoplankton pigment concentration is found throughout the entire visible spectrum and the model results are best at high spectral resolution (≤5 nm). The resulting model recreates observed relationships among pigment concentrations, providing support for the designation of five pigment-based phytoplankton groups for the global open ocean. This work represents a step toward developing robust, global spectral models for phytoplankton pigment composition. However, more high-quality data from a wide range of ecosystems and environments are still needed to achieve this goal.

Growth and Nutritional Quality of Lemnaceae Viewed Comparatively in an Ecological and Evolutionary Context.

This review focuses on recently characterized traits of the aquatic floating plant Lemna with an emphasis on its capacity to combine rapid growth with the accumulation of high levels of the essential human micronutrient zeaxanthin due to an unusual pigment composition not seen in other fast-growing plants. In addition, Lemna’s response to elevated CO2 was evaluated in the context of the source–sink balance between plant sugar production and consumption. These and other traits of Lemnaceae are compared with those of other floating aquatic plants as well as terrestrial plants adapted to different environments. It was concluded that the unique features of aquatic plants reflect adaptations to the freshwater environment, including rapid growth, high productivity, and exceptionally strong accumulation of high-quality vegetative storage protein and human antioxidant micronutrients. It was further concluded that the insensitivity of growth rate to environmental conditions and plant source–sink imbalance may allow duckweeds to take advantage of elevated atmospheric CO2 levels via particularly strong stimulation of biomass production and only minor declines in the growth of new tissue. It is proposed that declines in nutritional quality under elevated CO2 (due to regulatory adjustments in photosynthetic metabolism) may be mitigated by plant–microbe interaction, for which duckweeds have a high propensity.

Assessing Plant Pigment Regulation in Circadian Experiments.

Circadian rhythms affect many aspects of a plant's metabolism including, but not limited to, photosynthesis. Here, we provide a complete protocol for determining changes in the composition of photosynthetic pigments (chlorophyll and carotenoids), and we also consider its implementation within circadian experiments. We describe how to design a circadian experiment with the goal of assessing changes in pigment composition. We then perform two consecutive approaches to track changes in pigment composition: indirect noninvasive estimation of pigment composition (by reflectance or fluorescence) followed by direct pigment analysis (by chromatography or spectrophotometry). Finally, we present several considerations regarding data analyses.

Assessing grass water use efficiency through smartphone imaging and ImageJ analysis

Overwatering and underwatering grass are widespread issues with environmental and financial consequences. Current approaches to assessing grass water use efficiency (WUE) are inaccessible to the public. We developed an accessible method to assess grass WUE: combining smartphone imaging with open access color unmixing analysis. Images were converted from the RGB color space to the CIELAB color space using ImageJ—an open access, user-friendly software—to correct for uneven lighting without compromising image detail. We obtained parameters a* (unmixes green-to-red vector) and b* (unmixes blue-to-yellow vector). We hypothesized that WUE can be accurately determined from grass color and growth, which can be analyzed using CIELAB color unmixing. We tested how nine watering levels (100–900 mL every 4–5 days) affected Stenotaphrum secundatum (St. Augustine grass) over one month in Orange County, Southern California. Color was quantified using a*:b* ratios, growth was tracked using grass area, and pigment composition was analyzed using plot profiles. We analyzed whole samples in the uncontrolled real-world environment, individual leaves in a controlled homemade imaging box, and extracted pigments before and after paper chromatography. Results were clustered using Gaussian finite mixture models, implemented by R package ‘mclust’. Overall trends for grass coverage, a*:b* ratios, and pigment composition were consistent with real-world observations. Cluster analyses were consistent across image types, identified an ideal watering range (600–700 mL), and differentiated between underwatered and overwatered grass. Our hypothesis was supported. Our method can be applied in automated irrigation systems or apps, providing grass WUE assessment for regular consumer use.

ВЛИЯНИЕ НИЗКОИНТЕНСИВНОГО ЭЛЕКТРОМАГНИТНОГО ИЗЛУЧЕНИЯ МИЛЛИМЕТРОВОГО ДИАПАЗОНА НА ПИГМЕНТНЫЙ СОСТАВ И ФОТОСИНТЕТИЧЕСКУЮ АКТИВНОСТЬ TRITICUM AESTIVUM L. В УСЛОВИЯХ ХЛОРИДНОГО ЗАСОЛЕНИЯ

The purpose of this research was to study the effect of low-intensity electromagnetic radiation (EMP) of the millimeter (mm) range (wavelength – 7.1 mm, radiation frequency – 42.3 GHz, radiation power flux density – 0.1 mW / cm2, exposure 30 minutes, once) on the pigment composition and photosynthetic activity of juvenile plants of Triticum aestivum L., cultivar Selyanka, under osmotic stress caused by chloride salinity. To measure the intensity of photosynthesis, we used the assimilation flask method according to L. A. Ivanov and N. L. Kossovich, a colorimetric method was used to determine the amount of chlorophyll in wheat plants. Statistical processing of the data obtained was carried out using the Kruskell-Walliss test of reliability. All measurements and studies were carried out on equipment that passed metrological verification and expertise. The results of the study indicate that under the influence of low-intensity EMR of the MM range, the indicators of the amount of chlorophylls increase by 51.8 % compared to plants under osmotic stress; and compared with the control, the accumulation of chlorophyll increases by 23.2 %. In addition, the effect of this physical factor has a stimulating effect on the accumulation of chlorophyll and its content was 30.9 %, which is 46.6 % more than in the control variant. The stimulating effect of EMR is also observed at a concentration of 150 mM sodium chloride. With the use of EHF-radiation, the content of chlorophyll was 28.2 % of the mass of raw leaves, by 43.3 % compared to the experimental versions without the use of EHF-radiation. The intensity of photosynthesis under the influence of EHF-radiation increases in relation to the control by 14.0 %. Thus, a positive effect of low-intensity EMM of the mm range on the pigment composition and photosynthetic activity of Triticum aestivum L. both under optimal conditions and under conditions of osmotic stress has been established. The results obtained on the quantitative content of chlorophylls showed that their content increased both under normal conditions and under osmotic stress by an average of 20 %. An increase in the intensity of photosynthesis in experimental plants was established by 30.0 % in comparison with control plants under osmotic stress.

An in vivo plant platform to assess genes encoding native and synthetic enzymes for carotenoid biosynthesis.

This chapter provides an overview of how to test enzyme function in plants using candidate genes encoding carotenoid biosynthetic enzymes and/or engineered enzyme versions for synthetic biology applications. A step-by-step guide explains transformation and screening of Agrobacterium tumefaciens containing a binary vector, preparation of inoculum, and transient expression of candidate or retooled enzymes in Nicotiana benthamiana leaf tissue. In planta expression is especially useful for screening candidate carotenoid biosynthetic enzymes because many of the substrates that these enzymes would use are already present in the leaf. In this assay pigments are extracted from leaf discs expressing transgenes and changes in pigment profiles resulting from the activity of these introduced enzymes are scored using High Performance Liquid Chromatography (HPLC). If a transgene product modifies a carotenoid substrate, differences are easily revealed by comparison against wildtype pigment profiles. Additionally, this in planta method presents the researcher with an opportunity to evaluate candidate carotenoid biosynthetic enzyme function in the existing context of N. benthamiana photosynthetic chloroplasts. Photosynthetic phenotypes that arise from changes in pigment composition can be determined by Pulse Amplitude Modulated (PAM) fluorescence measurements, if desired.