Accumulation Of Photosynthetic Pigments Research Articles

Adaptation of the photosynthetic function of Juniperus communis L. in the mountainous middle taiga dark coniferous forests of the Southern Urals

The article studies the accumulation of photosynthetic pigments and the ratio of their forms in the needles of Juniperus communis L. in the mountainous middle taiga dark coniferous forests of the Southern Urals during the winter and summer periods in contrasting conditions of the tundra-clear forest transition zone within the same slope of Dalniy Taganay. The assessment of the morphophysiological state makes it possible to assess the adaptive capabilities of plants, which consist in changing the content and ratio of pigment forms, transformation of the life form, while the accumulation of the pigment composition does not depend on age. Adaptation of the photosynthetic apparatus at the level of the ratio of photosynthetic organs allows this species to maintain growth parameters and gain an advantage in light spruce forest conditions.

Physiological and Biochemical Behaviours and Antioxidant Response of Helianthus annuus under Lanthanum and Cerium Stress

The continuous progress of global manufacturing and anthropogenic activities has resulted in excessive environmental metallic pollution, particularly with rare earth elements (REEs) which have become a prevalent issue of global concern due to their high toxicity and widespread existence. REEs-contaminated soils could ruin agriculture by inducing plant physiology disturbances in various crops that are considered the principal link of the human food chain. The main purpose of the present work is to assess the phytotoxicity of two light REEs, lanthanum (La) and cerium (Ce), in Helianthus annuus after 14 days of exposure to different concentrations of La and Ce (0, 1, 2.5, 5, and 10 µM). Plants showed different variations in shoot and root lengths at the end of the trial period. The accumulation of photosynthetic pigments, such as chlorophylls and carotenoids, as well as the photosynthetic efficiency, the non-photochemical quenching, the photosynthetically active radiation, and the electron transport rate, increased in the two REE treatments. Hydrogen peroxide significantly increased in all applied concentrations of La and Ce. A significant increase in malondialdehyde content was noticed only when plants were exposed to 2.5 µM La and 10 µM Ce. Results also demonstrated that La and Ce induced an increase in the activity of superoxide dismutase, peroxidase, and catalase (only the highest concentration of La decreased catalase activity). The exposure to different REE concentrations induced the accumulation of La and Ce in the plants, mainly in roots. Helianthus annuus showed an effective resistance behaviour facing La- and Ce-induced stresses.

Obtaining Fat-Soluble Pigments—Carotenoids from the Biomass of Chlorella Microalgae

The aim of this study was to use a directed mode of cultivation of the microalgae Chlorella for biomass production, followed by the subsequent extraction of carotenoids. The effect of a stress inducer of carotenogenesis (hydrogen peroxide) and a growth stimulator (pyridoxine, vitamin B6) on the accumulation of photosynthetic pigments by the biomass of the microalga C. vulgarisBIN in the process of directed cultivation was studied. It was revealed that the combination of these additives in the culture medium increases the content of chlorophylls and carotenoids in the biomass twofold compared to the control sample. The preliminary activation of the biomass by high-speed ultra-homogenization (a rotor rotation range from 6000 to 12,000 rpm) was also investigated. Using ultrasound extraction, the pigment complex was isolated from the activated biomass. The saponification and subsequent neutralization of carotenoids were carried out in an inert medium. The resulting sample contained carotenoids in the amount of 52 ± 3 mg/mL. The chemical profile of the carotenoids in the biomass of the microalga Chlorella vulgaris BIN was also established. The major carotenoid was lutein (45%), followed by fucoxanthin (12%) and β-carotene (4.3%). The oil extract of the carotenoids may be used for the further production of a microencapsulated product with the aim of targeted delivery to the lower parts of the gastrointestinal tract.

Application of a Biostimulant (Pepton) Based in Enzymatic Hydrolyzed Animal Protein Combined With Low Nitrogen Priming Boosts Fruit Production Without Negatively Affecting Quality in Greenhouse-Grown Tomatoes.

Improved nutrient use efficiency together with the use of biostimulants have been little explored thus far to improve fruit yield and quality in economically relevant crops. The aim of this study was to determine the additive or synergistic effects, if any, of the application of an enzyme hydrolyzed animal protein biostimulant (Pepton) combined with priming with low nitrogen (N) in the production and quality of greenhouse tomatoes. Biostimulant treatment (Pepton at a dose equivalent of 4 kg/ha) was applied by ferti-irrigation for 2 months during the vegetative phase both in controls (watered with nutrient solution) and nutrient efficient crop (NEC), in which plants were primed with low N by exposing them to a 30% N deficiency for 2 months, and then recovered for 1 month before fruit production. Foliar water and N contents, pigments, maximum PSII efficiency (Fv/Fm ratio), and phytohormones [including abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), and cytokinins] were measured prior and at 4 and 8 weeks after the first application. Fruit production and quality [as indicated by total soluble sugars (TSS) and acidity (TA), and the contents of lycopene, vitamin E, and vitamin C] were measured 1 month later at harvest. Priming with low N availability (NEC plants) doubled (p < 0.001) fruit production (due to an increase in the number of fruits), tended to increase (p = 0.057) by 20% the amount of TSS and increased (p < 0.05) the contents of lycopene (by 90%) and vitamin E (by 40%). Pepton displayed a tendency, almost significant, to improve (p = 0.054) total fruit production both in control and NEC plants, thus showing an additive effect to low N priming in boosting fruit production. Pepton maintained fruit quality in terms of sugar accumulation, total acidity and the contents of carotenoids, vitamins C and E. Pepton-related improvement in fruit production seemed to be related, at least partially, to an increased accumulation of cytokinins and photosynthetic pigments in leaves, which might favor vegetative vigor and ultimately fruit yield. In conclusion, Pepton application was effective in improving the yield of greenhouse tomatoes showing additive effect with low N priming, without negatively affecting fruit quality.

Use of hydrogel in the irrigation management of white pitaya (Hylocereus undatus) seedlings: Biometrics and accumulation of organic and inorganic solutes

The initial development of pitayas may be limited by a few factors, among them, water deficit. Agricultural hydrogels can be used as an alternative to enhance the retention and availability of water and nutrients in the soil. Therefore, this study aimed to evaluate the influence of irrigation frequency and hydrogel doses on the development of white pitaya (Hylocereus undatus) seedlings to establish a time interval in days between irrigations that provides better seedling development and determine the hydrogel dose that provides a reduction of water consumption without damaging seedling development. The experimental design consisted of randomized blocks in a 4 x 4 factorial arrangement, in which the treatments corresponded to 4 hydrogel doses (0, 2, 4, and 6 g/plant of Biogel Hidro Plus) incorporated into the substrate and four irrigation frequencies (1, 3, 5, and 7 days of interval). The biometric characteristics, photosynthetic pigments, and organic and inorganic solutes of the plants were evaluated after 120 days. The use of daily irrigation negatively influenced the growth and biomass accumulation of the aerial part of the seedlings and, consequently, provided the lowest values of cladodes of the pitaya seedlings. Pitaya seedlings had greater development when using an irrigation frequency of around 3 days. The application of 6 g/plant of hydrogel provided the highest averages for accumulation of dry biomass, photosynthetic pigments, and organic and inorganic solutes at irrigation levels of 3.6, 4, and about 3.8 days of intervals, respectively. Hydrogel incorporation allowed increasing the interval between irrigations by 1 day without damages to the seedling development.

Physiological Response to Short-Term Heat Stress in the Leaves of Traditional and Modern Plum (Prunus domestica L.) Cultivars

The aim of this study was to evaluate physiological responses to short-term heat stress in the leaves of traditional (Bistrica) and modern (Toptaste) plum cultivars. In this study, detached plum leaves were incubated at 25 °C (control) and 40 °C (stress). After 1 h of exposure to heat (40 °C), chlorophyll a fluorescence transients were measured, and several biochemical parameters were analyzed. Elevated temperature caused heat stress in both plum cultivars, seen as a decrease in water content (WT), but in the leaves of the cultivar Bistrica, an accumulation of proline and phenols, as well as an accumulation of photosynthetic pigments, suggest the activation of a significant response to unfavorable conditions. Conversely, in the leaves of Toptaste, a significant accumulation of malondialdehyde (MDA) and an activation of guaiacol peroxidase (GPOD), all together with a decreased soluble proteins content, indicate an inadequate response to maintaining homeostasis in the leaf metabolism. The impact of an elevated temperature on photosynthesis was significant in both plum cultivars as reflected in the decrease in performance indexes (PIABS and PItotal) and the maximum quantum yield of PSII (Fv/Fm), with significantly pronounced changes found in Toptaste. Unlike the traditional plum cultivar, Bistrica, in the modern cultivar, Toptaste, short-term heat stress increased the minimal fluorescence (F0) and absorption (ABS/RC), as well as Chl b in total chlorophylls. Additionally, the inactivation of RCs (RC/ABS) suggests that excitation energy was not trapped efficiently in the electron chain transport, which resulted in stronger dissipation (DI0/RC) and the formation of ROSs. Considering all presented results, it can be presumed that the traditional cultivar Bistrica has better tolerance to heat stress than the modern cultivar Toptaste. The cultivar, Bistrica, can be used as a basis in further plum breeding programs, as a source of tolerance for high temperature stress.

Seed germination and physiological responses of quinoa to selenium priming under drought stress

The early stages of quinoa germination are sensitive to drought stress. For this purpose, a study entitled the effect of selenium in different concentrations on germination characteristics and some antioxidant enzymes of quinoa under drought stress conditions with polyethylene glycol (PEG 6000) was investigated. The first experimental factor was seed priming with selenium (from two sources: sodium selenate and selenium nanoparticles: SeNPs ? 33.4 nm) at 0.5, 1.5, 3, 4.5, 6 mg·L?1 concentrations, besides, no priming treatment was used as control. The second factor was drought stress with PEG 6000 in concentrations 0, –0.4, –0.8, and –1.2 MPa. Drought stress with accumulation of reactive oxygen species (ROS) had a negative effect on most of the measured traits. In seeds that were primed with appropriate selenium concentrations, germination parameters and antioxidant enzyme activity as well as proline and protein content increased compared to the control treatment. Under conditions of severe stress (–1.2 MPa), the highest activity of catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX) enzymes was observed in prime with selenium nanoparticles at concentrations of 4.5, 6.0 and 4.5 mg·L?1, respectively. Concentrations higher than 3 mg·L?1 of selenium nanoparticles and concentrations of 3 mg·L?1 sodium selenate had the highest accumulation of photosynthetic pigments under control (stress-free) conditions. The present study shows that selenium priming can reduce the harmful effects of drought stress on quinoa by altering germination properties and biochemical properties.

The Anthurium APRR2-like Gene Promotes Photosynthetic Pigment Accumulation in Response to Salt Stress

The Anthurium APRR2-like Gene Promotes Photosynthetic Pigment Accumulation in Response to Salt Stress

Genome-mining for stress-responsive genes, profiling of antioxidants and radical scavenging metabolism in hyperaccumulator medicinal and aromatic plants

Medicinal and aromatic plants (MAPs) possess phytoremediation potential owing to antioxidants, secondary metabolites, and morphological features. Moringa oleifera, Pelargonium graveolens, Tagetes patula, and Calotropis gigantea are known for their phytoremediation properties in heavy metals polluted soil. These plants with phytoremediation properties due to antioxidants, specific secondary metabolites synthesis, and distinctive morphological characteristics ultimately become the ideal choice for effective remediation. The main aim of the current study is to provide a genetic evaluation using bioinformatics techniques, antioxidant compounds, metabolites, and their activity. Genomic and transcriptomic studies endorsed genes related to hyperaccumulation in these plant species having essential domains as catalase (CAT) and superoxide dismutase (SOD_Cu, SOD_Fe_C, and SOD_Fe_N). The phylogenetic study showed its close evolutionary relationship to other plant species. The accumulation of total photosynthetic pigments, carotenoids, non-enzymatic antioxidants, and enzymatic antioxidants determined spectrophotometrically, involved in stress tolerance and ROS homeostasis maintenance mechanisms. Tagetes leaves showed the highest proline, flavonoids, and phenolics content, while Moringa showed higher CAT, guaiacol peroxidase (G-POD), and glutathione peroxidase (GPX) activities. Results also revealed that plants accumulated more primary and secondary metabolites in young tissue to tackle pathogens, herbivores, attract pollinators, and in mature tissues to develop strong physiology. Total antioxidant activity, reducing power, and radical scavenging activities were observed. These MAPs have intriguing antioxidant characteristics and a phytochemical composition that might give scientific support for their stress tolerance and ROS management activities. The study establishes the groundwork for using MAPs as phytoremediators; further confirmatory research is required for their use in sustainable phytoremediation.

Effects of Light Spectral Quality on the Micropropagated Raspberry Plants during Ex Vitro Adaptation.

This work focuses on developing light environments for the effective regulation of morphogenesis and ex vitro conditions adaptation in micropropagated raspberry plants on the basis of photomorphogenetic control of physiological processes using light-emitting diodes (LEDs). In experiments with cloned plants growing ex vitro in stressful conditions during acclimation, the effects of optical radiation of various spectral combinations from different photosynthetically active radiation (PAR) spectral regions were studied. The data on the plant development and state of the photosynthetic apparatus, features of photosynthetic gas exchange and transpiration, accumulation of photosynthetic pigments, light curves of photosynthesis, and data on growth processes in light modes using combined quasimonochromatic radiation (either mixture of red, green, and blue light or red, far-red, and blue light) with various ratio of the distinct spectral regions were obtained. Photosynthetic apparatus functional activity under different light conditions was studied with chlorophyll fluorescence determination, and plant stress responses to growing under artificial spectral light conditions were characterized. The experiments were accompanied by detailed plant phenotyping at the structural and functional levels. Plant acclimation and photosynthetic improvements in response to added far-red and green light wavelengths to the main red-blue spectrum have been elucidated.

Fine-tuning of grapevine xanthophyll-cycle and energy dissipation under Mediterranean conditions by kaolin particle-film

Kaolin-particle film has been considered a low-cost technology to mitigate the adverse effects of high light and temperature, and drought in several crops. However, the underlying excess energy absorption and dissipation mechanisms, and related components associated with kaolin photoprotective effects in grapevines are poorly explored. This study aims to understand the interactions between kaolin foliar treatment and photosynthetic pigments accumulation, carotenoids metabolism, xanthophyll cycle regulation, and its putative role on the non-photochemical quenching (NPQ) processes in Touriga-Franca (TF) and Touriga-Nacional (TN) varieties. The experiments were conducted during the 2017 summer season in a commercial vineyard, and measurements were performed at pre-dawn and midday in each sampling date (EL35 – veraison; EL38 – full mature). Overall, TF variety showed higher accumulation of chlorophylls, xanthophylls, and de-epoxidation state (DPS) than TN. Kaolin treatment enhanced TN chlorophyll accumulation up to 114 % at EL35 (veraison) and 123 % at EL38 (full mature), highlighting its protective role on chlorophyll degradation, while no changes were found in TF, which might indicate a lower need for particle-film technology in this variety under the current environmental conditions. Individual carotenoids were mainly higher in the treated leaves of both varieties, as well as the xanthophyll cycle pigments zeaxanthin (Zx) and violaxanthin (Vx). Simultaneously, the DPS and NPQ values were lower in TN and TF treated leaves (1.92 – 2.36) compared to untreated vines (3.19 – 3.24), suggesting that there might be other components influencing NPQ levels beyond Zx, with an indirect role in long-lasting NPQ processes. In addition, in the TF kaolin-treated leaves, violaxanthin de-epoxidase (VvVDE1) and zeaxanthin epoxidase (VvZEP1) gene expression were respectively 3-fold and 4-fold upregulated at stage EL35, while VvZEP1 gene expression decreased at stage EL38 in TN kaolin-treated leaves, indicating an optimised regulation of the xanthophyll cycle. These findings suggest that kaolin treatment promoted a fine-tuning of grapevine summer stress responses under sustained summer stress factors, by managing xanthophyll cycle dynamics, and pigments accumulation.

Development of a mixotrophic cultivation strategy for simultaneous improvement of biomass and photosynthetic efficiency in freshwater microalga Scenedesmus obliquus by adding appropriate concentration of sodium acetate

To study the biomass and photosynthetic efficiency difference of freshwater microalga Scenedesmus obliquus under autotrophic and mixotrophic cultivation mode, the biomass production, photosynthetic pigments, and photosynthetic efficiency were investigated by lab-scale cultivation experiments. Specifically, S. obliquus was cultured in BG11 medium supplemented with different concentrations of exogenous sodium acetate to examine the physiological and biochemical effects on the oil rich freshwater algae S. obliquus. Results showed that exogenous sodium acetate exerted a “low promotion and high suppression” effect on the biomass production and photosynthetic pigments accumulation, and the biomass production and pigment contents peaked at a sodium acetate concentration of 10.00 mg L−1. Meanwhile, photosynthetic efficiency was significantly increased under low concentration of sodium acetate, however, when adding the high concentrations of sodium acetate, the oxygen evolving complex in donor side of reaction center was damaged, and electron transport at the donor and receptor sides of the reaction center was also suppressed, accompanied by the changes of the absorption, transfer, and application of light energy. These findings provide a strategy to boost biomass accumulation of S. obliquus by mixotrophic cultivation mode with appropriate concentration of sodium acetate, and would be conducive to further accelerate the industrialization of this strain.

Accumulation of photosynthetic pigments and indicators of fluorescence of chlorophyll in leaves of &lt;i&gt;Dioscorea alata&lt;/i&gt; L. during vegetative reproduction of plants on ion-exchange substrates

The content of photosynthetic pigments and fluorescence of chlorophylls in leaves of Dioscorea alata L. plants grown on a modified ion-exchange substrate were studied. It was found that in the variant with the addition of a fine fraction to the hydrogel substrate in an amount of 1 g/l, the Chl а content is 15 % higher than in the control. The content of Chl b and carotenoids in comparison with the control differed insignificantly. When the hydrogel was added at a concentration of 0.5 g/l, the Chl а content in all studied variants was significantly lower than the control.Based on the investigated parameters of chlorophyll fluorescence, the most favorable conditions for the productivity of photosynthesis were in the variant with the addition of 1 g of a fine fraction and illumination of DNaT-400.

Light Quality-Dependent Regulation of Non-Photochemical Quenching in Tomato Plants.

Simple SummaryPhotosynthetic organisms, such as land plants, evolved to utilize available light and to use its energy to assimilate carbon dioxide and produce carbohydrates. However, the light intensity often exceeds the ability of plants to successfully utilize absorbed energy, thus inducing stress, manifested by an increased radical concentration inside plant cells and disruption of the inner structures, and consequently decreased plant yield. Plants solve this problem by using a mechanism termed non-photochemical quenching, by which they can dissipate the energy not used in photosynthesis. Modern agriculture, however, also involves indoor plant farming. For indoor plant farming LED-based lighting systems, with non-saturating light intensities, are suitable based on their restricted energy consumption. However, the composition of applied light should first be optimized to maximize its utilization. Our study examined the influence of monochromatic LEDs (red, green, and blue) on the photoprotective and photosynthetic properties of tomato plants. We indicate that monochromatic green light could be considered an important component of lighting systems to alleviate energy dissipation, while blue light enhances photosynthetic efficiency. Our study not only proves the crucial importance of spectrum optimization but also provides evidence that different light wavelengths modify photosynthetic and photoprotective properties.Photosynthetic pigments of plants capture light as a source of energy for photosynthesis. However, the amount of energy absorbed often exceeds its utilization, thus causing damage to the photosynthetic apparatus. Plants possess several mechanisms to minimize such risks, including non-photochemical quenching (NPQ), which allows them to dissipate excess excitation energy in the form of harmless heat. However, under non-stressful conditions in indoor farming, it would be favorable to restrict the NPQ activity and increase plant photosynthetic performance by optimizing the light spectrum. Towards this goal, we investigated the dynamics of NPQ, photosynthetic properties, and antioxidant activity in the leaves of tomato plants grown under different light qualities: monochromatic red (R), green (G), or blue (B) light (L) at 80 µmol m−2 s−1 and R:G:B = 1:1:1 (referred to as the white light (WL)) at 120 µmol m−2 s−1. The results confirm that monochromatic BL increased the quantum efficiency of PSII and photosynthetic pigments accumulation. The RL and BL treatments enhanced the NPQ amplitude and showed negative effects on antioxidant enzyme activity. In contrast, plants grown solely under GL or WL presented a lower amplitude of NPQ due to the reduced accumulation of NPQ-related proteins, photosystem II (PSII) subunit S (PsbS), PROTON GRADIENT REGULATION-LIKE1 (PGRL1), cytochrome b6f subunit f (cytf) and violaxanthin de-epoxidase (VDE). Additionally, we noticed that plants grown under GL or RL presented an increased rate of lipid peroxidation. Overall, our results indicate the potential role of GL in lowering the NPQ amplitude, while the role of BL in the RGB spectrum is to ensure photosynthetic performance and photoprotective properties.

Synthesis and biological activity of N6-mannopyranosyladenines

In this work, potentially bioactive condensation products of adenine with D-mannose and 6-deoxy-L-mannose (L-rhamnose) were synthesized in water and ethanol solutions. According to FTIR spectroscopy and elemental analysis, mono-N6-glycosylated adenines were isolated from water systems in satisfactory yields, while ethanol solutions contained mixtures of N6 and N9-products, as well as complexes of the latter with copper ions. A detailed analysis of the vibrational spectra of N6-glycosyladenines confirmed the structure of carbohydrate fragments in the form of pyranose rings, while some part of the product was obtained in the form of deoxyaminoketosis. N-rhamnosyladenine was formed with a more than double yield because of a higher stability of rhamnose with regard to side reactions. The reflection spectra of model solutions of glycosyladenines, recorded 4 days after preparation, showed no bands characteristic of free adenine in the range of 1250-1110 cm-1, which indicates a sufficient resistance of the synthesized products towards hydrolytic cleavage under experimental conditions. The conducted biotesting of the isolated products on wheat seeds (Triticum aestivum L.) showed an increase in the content of chlorophylls in seedlings for both mannosilade-nines compared to the control. A decrease in the concentration of synthesized products in germination solutions from 0.1 to 0.001% led to an increase in the accumulation of photosynthetic pigments, while this effect was more pronounced for rhamnosyladenine. The latter can be connected with the structural features of car-bohydrate fragments, in particular, the differences in the hydroxylation degree of glucoside fragments. Future research will investigate the mechanisms of transformation and action of N6-substituted adenines.

NaCl-Induced Elicitation Alters Physiology and Increases Accumulation of Phenolic Compounds in Melissa officinalis L.

In nature, plants usually produce secondary metabolites as a defense mechanism against environmental stresses. Different stresses determine the chemical diversity of plant-specialized metabolism products. In this study, we applied an abiotic elicitor, i.e., NaCl, to enhance the biosynthesis and accumulation of phenolic secondary metabolites in Melissa officinalis L. Plants were subjected to salt stress treatment by application of NaCl solutions (0, 50, or 100 mM) to the pots. Generally, the NaCl treatments were found to inhibit the growth of plants, simultaneously enhancing the accumulation of phenolic compounds (total phenolics, soluble flavonols, anthocyanins, phenolic acids), especially at 100 mM NaCl. However, the salt stress did not disturb the accumulation of photosynthetic pigments and proper functioning of the PS II photosystem. Therefore, the proposed method of elicitation represents a convenient alternative to cell suspension or hydroponic techniques as it is easier and cheaper with simple application in lemon balm pot cultivation. The improvement of lemon balm quality by NaCl elicitation can potentially increase the level of health-promoting phytochemicals and the bioactivity of low-processed herbal products.

Effect of exogenous silicon and methyl jasmonate on the alleviation of cadmium-induced phytotoxicity in tomato plants.

In the present study, a hydroponic experiment was performed to evaluate the effect of exogenous silicon (Si) and methyl jasmonate (MeJA) on the mitigation of Cd toxicity in tomato seedlings. The results revealed that Cd-stressed plants exhibited growth inhibition, increased lipid peroxidation, and impaired photosynthetic pigment accumulation. However, Si and MeJA applied alone or in combination significantly ameliorated the above-mentioned adverse effects induced by Cd. Among all treatments, Cd+Si+MeJA treatment elevated the dry mass of roots, stems, and leaves by 317.39%, 110.85%, and 119.71%, respectively. The chlorophyll a, chlorophyll b, and carotenoid contents in Cd+Si+MeJA-treated group were dramatically elevated (p < 0.05). Meanwhile, the malondialdehyde content in roots and shoots were reduced by 32.24% and 69.94%, respectively. The Si and MeJA applied separately or in combination also resulted in a prominent decrease of Cd influxes in tomato roots; therefore, a reduction of Cd content in tomato tissues were detected, and the Cd concentration in tomato roots were decreased by 27.19%, 25.18%, and 17.51% in Cd+Si, Cd+MeJA and Cd+Si+MeJA-treated plants, respectively. Moreover, in Cd+Si+MeJA-treated group, the percentage of Cd in cell wall fraction was enhanced while that in organelle fraction was decreased as compared with Cd-stressed plants. Collectively, our findings indicated that Si and MeJA application provide a beneficial role in enhancing Cd tolerance and reducing Cd uptake in tomato plants.

Artificial light source selection in seaweed production: growth of seaweed and biosynthesis of photosynthetic pigments and soluble protein.

Seaweed growth is often limited by light. Artificial light supply has been well studied in terrestrial agriculture, however, much less is known about its effect in seaweed aquaculture. In this study, the effects of four artificial light sources (white, red, green, and blue LEDs light) on a brown alga Sargassum fusiforme and a green alga Ulva pertusa were investigated. Seaweed growth, accumulation of photosynthetic pigments (chlorophyll a and carotenoid), and soluble protein were evaluated. White LED light was the optimal supplementary light when cultivating Ulva pertusa and Sargassum fusiforme, because it promoted seaweed growth while maintaining protein production. Meanwhile, red LED was unfavored in the cultivation of S. fusiforme, as it affected the seaweed growth and has a lower residual energy ratio underneath the water. LEDs would be a promising supplementary light source for seaweed cultivation.

Photon flux density and wavelength influence on growth, photosynthetic pigments and volatile organic compound accumulation in Aeollanthus suaveolens (Catinga-de-mulata) under in vitro conditions

Aeollanthus suaveolens Mart. ex Spreng. (Lamiaceae) is an aromatic plant of African origin and is widely used in folk medicine due to its anticonvulsant and sedative effects. The aim of the study was to establish whether photon flux density (PFD) and wavelength, provided by light emitting diodes (LEDs), affect plantlet growth, photosynthetic pigment, and volatile organic compound (VOC) accumulation in Aeollanthus suaveolens. Nodal segments were grown under different PFDs (20, 57, 78, 102 and 139 μmol m−2 s−1) obtained with white LEDs lamps and under different LEDs light spectra as follows: white, green, yellow, blue, red, and combinations of red and blue (2.5R:1B; 1R:2.5B; 1R:1B) and cool white fluorescent lamps. The different light intensities affected the growth and production of photosynthetic pigments and volatile organic compounds. Plantlets grown under a PFD of 139 μmol m−2 s−1 showed greater dry weight accumulation and growth than those raised under other PFDs. The chlorophyll and carotenoid contents increased with a PFD of 20 μmol m−2 s−1. Light quality also affected plantlet growth. White LEDs light and fluorescent light were equally effective for growth and dry weight accumulation. Monochromatic red, blue, and yellow lights inhibited growth in Aeollanthus suaveolens. The concentrations of photosynthetic pigments from A. suaveolens plantlets were significantly affected by different wavelengths. Yellow wavelengths favored the production of photosynthetic pigments. The accumulation of VOCs was influenced by PFD and spectral quality.

Photosynthetic profiling of a Dunaliella salina mutant DS240G-1 with improved β-carotene productivity induced by heavy ions irradiation

Carbon-ion irradiation is a technique for trait improvement in the microalgae, but the underlying mechanisms that how it altered the biomass, and photosynthetic pigments accumulation were unclear. One mutant (DS240G-1) was obtained from Dunaliella salina by heavy ion irradiation mutagenesis. Compared to the wild type, the biomass accumulation and maximum growth rate of DS240G-1 were increased by 34% and 55% respectively, and its β-carotene content was 21% higher than the wild type. Subsequent analysis of the chlorophyll fluorescence parameters indicated that higher β-carotene productivity was likely owing to the improved maximum quantum efficiency (Fv/Fm) and decreased thermal dissipation of photosynthesis in DS240G-1 than that of wild type during cultivation. In addition, the result of this study revealed that high content of ROS may induce β-carotene accumulation in mutant DS240G-1. Also, the total fatty acid (TFA) content in mutant DS240G-1 was 79% higher than that in wild type. Owing to its high β-carotene productivity and total fatty acid content, DS240G-1 could be considered as a promising candidate for microalgae β-carotene and biodiesel production. This work provided the first insight into the biological effects involved in carbon-ions irradiation on the photosynthetic activity of D. salina. Keywords: microalgae, D. salina, carbon-ions irradiation, chlorophyll fluorescence, β-carotene DOI: 10.25165/j.ijabe.20211402.5993 Citation: Xi Y M, Liu Y, Chi Z Y, Yin L, Wang L J, Luo G H. Photosynthetic profiling of a Dunaliella salina mutant DS240G-1 with improved β-carotene productivity induced by heavy ions irradiation. Int J Agric & Biol Eng, 2021; 14(2): 211–217.