Synthesis Of Photosynthetic Pigments Research Articles

Comparative Physiological and Biochemical Changes in Tomato (Solanum lycopersicum L.) Under Salt Stress and Recovery: Role of Antioxidant Defense and Glyoxalase Systems.

Salinity toxicity and the post-stress restorative process were examined to identify the salt tolerance mechanism in tomato, with a focus on the antioxidant defense and glyoxalase systems. Hydroponically grown 15 day-old tomato plants (Solanum lycopersicum L. cv. Pusa Ruby) were treated with 150 and 250 mM NaCl for 4 days and subsequently grown in nutrient solution for a further 2 days to observe the post-stress responses. Under saline conditions, plants showed osmotic stress responses that included low leaf relative water content and high proline content. Salinity induced oxidative stress by the over-accumulation of reactive oxygen species (H2O2 and O2•−) and methylglyoxal. Salinity also impaired the non-enzymatic and enzymatic components of the antioxidant defense system. On the other hand, excessive Na+ uptake induced ionic stress which resulted in a lower content of other minerals (K+, Ca2+, and Mg2+), and a reduction in photosynthetic pigment synthesis and plant growth. After 2 days in the normal nutrient solution, the plants showed improvements in antioxidant and glyoxalase system activities, followed by improvements in plant growth, water balance, and chlorophyll synthesis. The antioxidant and glyoxalase systems worked in concert to scavenge toxic reactive oxygen species (ROS), thereby reducing lipid peroxidation and membrane damage. Taken together, these findings indicate that tomato plants can tolerate salinity and show rapid post-stress recovery by enhancement of their antioxidant defense and glyoxalase systems.

Phytoremediation of anaerobically digested swine wastewater contaminated by oxytetracycline via Lemna aequinoctialis: Nutrient removal, growth characteristics and degradation pathways

The concentration of antibiotics in anaerobically digested swine wastewater (ADSW) usually gradually increases due to the addition of antibiotics in livestock feed. Lemna aequinoctialis was used to treatment synthetic ADSW contaminated by oxytetracycline (OTC) whose concentrations were 0.05, 0.25, 0.50 and 1.00 mg/L, and its influences on NH3-N and TP remove were investigated. The fresh weight, photosynthetic pigment and protein content of duckweed were also investigated. Results have shown that nutrient removal and duckweed growth followed the “dose-response” relationships, and 0.05 mg/L OTC could significantly promote the synthesis of photosynthetic pigments and proteins in duckweed. Meanwhile, the protein content gradually decreased during investigation. More important, the degradation products and possible degradation pathways of OTC were diagrammatized via liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), and twelve intermediates were detected in the duckweed systems. This study can offer a novel view for phytoremediation of ADSW containing antibiotics by aquatic plants.

Whole community estimates of macroalgal pigment concentration within two southern New Zealand kelp forests1.

Light availability is a fundamental factor that controls the productivity and distribution of macroalgae and is highly variable, both spatially and temporally, in subtidal coastal systems. Our comprehension of how macroalgae respond to such variability is a significant knowledge gap that limits our understanding of how light influences the structure and productivity of these environments. Here, we examined the pigment characteristics of individual species, and for the first time the whole community, within one low-light, and one high-light kelp-forest system in southern New Zealand. The aim was to quantify the range of pigmentation seen within the two kelp-forests which differed in irradiance regime. Light availability was 33% and 64% greater at the high-light compared to the low-light site at 2 and 10m depth, respectively. Results suggested Phaeophyceae species at deeper depths in the low-light site may be living at the edge of their photosynthetic ability and pigment synthesis appeared significantly restricted. Even with greater investment in the pigment fucoxanthin, biomass of Phaeophyceae species was significantly lower in the low-light site. Highly pigmented Rhodophyceae species made a greater proportional contribution to community biomass within the low-light site where they likely possessed a photosynthetic advantage. This work helps explain discrepancies in community structure between the two study sites and explores the complex relationship between irradiance and photoacclimation. The comparison of community pigment concentration holds potential as a tool for assessing the relative degree of photoacclimation occurring between sites and provides a proxy of photosynthetic cost under a specific light regime.

Effect of immunity inductors on the structural and functional state of photosynthetic apparatus and oxidative status of cucumber plants (cucumis sativus l.) Infected by Fusarium oxysporum

The effect of inductors of the immune response of β-aminobutyric acid (BABA), β-1.3-glucan (GK), salicylic acid (SA) and their mixture on the structural and functional state of photosynthetic apparatus and the oxidative status of cucumber plants under infection by fungal pathogen Fusarium oxysporum was studied. It was found that the disorganizing effect of the pathogenic fungus Fusarium oxusporum in cucumber plants caused the suppression of the synthesis of photosynthetic pigments and the functional activity of the photosystem 2 in chloroplast membranes, as well as in changing the character of the redistribution of absorbed light energy, leading to a decrease in the photochemical energy conversion (qP) and enhancing non-photochemical quenching (qN) of chlorophyll. In this conditions intensification of lipid peroxidation processes was observed. The use of immunomodulators such as BABA, GK and SA promotes the improvement of the adaptive properties of the photosynthetic apparatus, and the reduction of oxidative processes activity in infected cucumber leaves, which indicates the protective role of these substances against the fusarious wilt caused by Fusarium oxysporum.

Biochar alleviates fluoride toxicity and oxidative stress in safflower (Carthamus tinctorius L.) seedlings

An original research was laid out as factorial to evaluate the possible effects of biochar (0, 25 and 50 g kg−1 soil) on mitigating fluoride toxicity (non-contamination, 100, 200, 400 and 800 mg NaF kg−1 soil) in safflower seedlings. Increasing fluoride toxicity up to 200 mg NaF kg−1 soil did not decrease the safflower growth. However, the growth of plants under 400 and 800 mg NaF kg−1 was reduced by enhancing soluble fluoride concentration in the soil. This growth reduction was the consequence of an increase in fluoride content of plant tissues, generation of super oxide radicals and hydrogen peroxide, lipid peroxidation, misbalancing potassium and calcium ions, and a decrease in synthesis of photosynthetic pigments including chlorophylls, carotenoids, anthocyanin, flavonoids and xanthophyll's and photochemical efficiency of photosystem II. Application of biochar decreased the fluoride solubility, fluoride content of plant tissues, oxidative stress and antioxidant enzymes activities, leading to an increase in cation exchange capacity of soil and the pH, calcium and potassium uptakes, maximum efficiency of photosystem II, synthesis of photosynthetic pigments, and plant growth. In general, addition of 50 g biochar to 1 kg soil was the best treatment for alleviation of the fluoride toxicity in safflower plants.

Nitrogen modulation under chemostat cultivation mode induces biomass and lipid production by Chlorella vulgaris and reduces antenna pigment accumulation

Algal growth limitation in large-scale cultivation mostly results from high level synthesis of photosynthetic pigments, owing to self-shading effects and attenuation of light distribution. To overcome this problem, here we investigated the influence of nitrogen modulation on changes in antenna pigments as well as biomass and lipid production by Chlorella vulgaris under a chemostat continuous cultivation mode. The production of algal antenna pigments, including chlorophylls and carotenoids, was promoted in a total nitrogen (TN) concentration-dependent manner. Maximum algal biomass and lipid production were obtained from 70 mg/L of TN concentration along with a significant increase in light transmittance and reduction in antenna pigments. Furthermore, the composition of polyunsaturated fatty acids remarkably augmented at low TN concentrations. These results suggest that the reduction in algal antenna pigment synthesis via modulation of nitrogen concentration may serve as an effective strategy to enhance algal biomass and lipid production.

Photosynthetic pigments and photochemical efficiency of precocious dwarf cashew (<i>Anacardium occidentale</i> L.) under salt stress and potassium fertilization

Cashew cultivation is an activity of great socioeconomic relevance, especially for agriculture in the semi-arid region of Northeast Brazil, standing out as an option to generate jobs and income. Thus, the present study aimed to evaluate the photosynthetic pigments and photochemical efficiency of precocious dwarf cashew under salt stress and potassium fertilization. The study was conducted using a Regolithic Neosol with sandy loam texture, adopting a randomized block design in 5×2 factorial arrangement, which corresponded to five levels of electrical conductivity of irrigation water—ECw (0.4; 1.2; 2.0; 2.8 and 3.6 dS m-1) associated with two doses of potassium fertilization—KD (100 and 150% of recommendation), with three replicates and two plants per plot. Increasing water salinity inhibited chlorophyll synthesis and decreased electron transport rate and quantum yield of non-regulated energy dissipation in precocious dwarf cashew, at 50 days after sowing. There was significant interaction for chlorophyll a and b contents and the effects of salt stress were intensified by potassium doses on the chlorophyll b content of precocious dwarf cashew. Potassium doses of 100 and 150% of recommendation (150 and 225 mg K2O kg-1 of soil) do not mitigate the effect of salt stress on photosynthetic pigment synthesis and photochemical efficiency of cashew plants in the rootstock formation phase.

Glucose addition‐induced changes in the growth and chemical compositions of a freshwater microalga Chlorella kessleri

AbstractBACKGROUNDIn recent years, mixotrophic culture of algal cells has been gaining increasing interest, largely because it offers an efficient means of commercial production of lipids and other value‐added products. In this work, the impacts of glucose addition on the biomass production, chemical composition and fatty acid profiles of Chlorella kessleri were investigated to exploit the relationships between extra organic carbon and changes in the distribution of chemical compositions in algal cells.RESULTSResults showed that C. kessleri grew fast in the mixotrophic cultures with a maximum algal biomass and specific growth rate of 4.46 g L−1 and 1.27 day−1, respectively. Glucose in the cultures was absorbed and utilized effectively by this alga, whose uptake efficiencies ranged from 88.2% to 98.3%, but it had a negative impact on the synthesis of photosynthetic pigments. Additionally, the culture's pH and chemical composition, including pigments, carbohydrate, protein and lipids, in this alga varied with the change of glucose concentrations in the cultures. The fatty acid profiles of this alga indicated that its biomass could be used as live feeds in aquaculture or a good‐quality feedstock for biodiesel production.CONCLUSIONSThese results suggested that adding an extra organic carbon source (glucose) to a photoautotrophic culture was a potentially effective way to improve the performance in mixotrophically culture of microalgae, for example in terms of higher biomass and lipid production. © 2018 Society of Chemical Industry

Exogenous melatonin improves lead tolerance of bermudagrass through modulation of the antioxidant defense system

Lead (Pb) is a major anthropogenic contaminant that can be devastating on both animals and plants. It is essential to develop methods to decrease the Pb contaminant in soil by phytoremediation using plants that are tolerance to Pb. In this study, we investigated the tolerance of bermudagrass (Cynodon dactylon (L.) Pers.) and the role of exogenous application of melatonin for improving its tolerance to Pb. Bermudagrass growing in soil treated with Pb at 1,000 or 2,000 mg kg−1 were assessed with or without melatonin pretreatment at various concentrations. Under Pb stresses, bermudagrass plants showed stunted growth and increased cellular oxidative stress. Pre-treating bermudagrass plants with melatonin at 20 or 100 μM significantly increased the activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase) and the contents of non-enzymatic antioxidants (ascorbic acid and glutathione), and decreased reactive oxygen species (hydrogen peroxide, superoxide), and ultimately reduced membrane lipid peroxidation and permeability. These changes contributed to improvements in the water status, photosynthetic pigment synthesis, and biomass production of bermudagrass under Pb stresses. Our study provides the first evidence that melatonin may be a promising tool for enhancing Pb tolerance and phytoremediation potential of bermudagrass.

Azospirillum lipoferum FK1 confers improved salt tolerance in chickpea (Cicer arietinum L.) by modulating osmolytes, antioxidant machinery and stress-related genes expression

High salinity restricts crop growth and yield. Plant growth-promoting soil rhizobacteria boost crops growth and ameliorate the adverse effects of salt stress through regulating several physiological, biochemical and molecular processes. This study investigated the effects of Azospirillum lipoferum FK1 strain on chickpea (Cicer arietinum L.) growth and performance under saline conditions (0, 75 and 150 mM NaCl). Salt stress adversely decreased growth, biomass yield, nutrient acquisition, chlorophyll content, gas exchange parameters and total phenolic and flavonoid content of chickpea plants. However, salt stress induced the carotenoid content, osmolytes level, electrolyte leakage, H2O2 content, malondialdehyde level, and levels of enzymatic and non-enzymatic antioxidants in chickpea. Moreover, the expressions of three antioxidants genes (CAT, APX and SOD) and six genes conferring abiotic stress tolerance (PAL, PPO, CHS, CHI, DREB2A and IFS) was induced by high salinity. On the other hand, inoculation of salt-treated chickpea plants with Azospirillum lipoferum FK1 significantly improved nutrient acquisition, growth, biomass, photosynthetic pigment synthesis, osmolytes level, gas exchange attributes, phenols and flavonoids content, and enzymatic and non-enzymatic antioxidant levels in chickpea plants when compared to those exposed to NaCl only. Moreover, inoculated plants revealed lower levels of electrolyte leakage, H2O2 and MDA under saline conditions in relative to plants subjected to salt alone. Inoculated plants exhibited the highest expression level of the antioxidants genes and genes conferring salt tolerance under 150 mM NaCl concentration. Taken together, these findings demonstrated the beneficial role of Azospirillum lipoferum FK1 in alleviating the inhibitory impacts of salinity on chickpea growth via modulating osmolytes, antioxidants machinery and stress-related genes expression.

Effects of soil bulk density on growth, physiology and quality of Glechoma longituba

Through the determination of the growth, physiological and active components of Glechoma longituba, the effect of soil bulk density on growth and quality of G. longituba was explored. Through pot experiment, six different bulk density treatments were set for 0.8, 0.9, 1.0, 1.1, 1.2, 1.3 g·cm⁻³ , the growth index, physiological index and the content of active components were determined. The results showed that the growth indexes and biomass of G. longituba firstly increased and then decreased with the increase of soil bulk density. The dry weight of G. longituba achieved the maximum 5.70 g in the treatment of 1.0 g·cm⁻³ . The photosynthetic pigments, soluble sugars and free amino acids firstly increased and then decreased with the increase of soil bulk density. The suitable soil bulk density was beneficial to the accumulation of photosynthetic pigment, soluble protein and free amino acid synthesis. The content of malondialdehyde increased gradually with the increase of soil bulk density. The contents of ethanol-soluble extractives of G. longituba were greater than 25%, meeting its quality criterionin Chinese Pharmacopoeia 2015, achieved the maximum of 40.66% in the treatment of 1.0 g·cm⁻³ . The total flavonoids content of G. longituba increased gradually with the increase of soil bulk density, triterpenic acid and phenolic acids decreased gradually with the increase of soil bulk density. Soil bulk density has a significant effect on the growth and quality of G. longituba, and it is conducive to the growth and its medicinal quality at the soil bulk density of 1.0 g·cm⁻³.

Adaptation of corn plants to chronic ultraviolet irradiation

Aim. The adaptation of young corn plants (Zea mays L.) to the effect of chronic ultraviolet B (UV-B) irradiation during vegetative growth and formation of photosynthetic apparatus of leaves was studied. Methods. Corn plants hybrid Dostatok 300 MB in the phase of two developed leaves was irradiated with UV-B in dose of 2 kJ/m2 per day with a power of 1 W/m2 in long day conditions during 12 days. During this period, the growth of plants was measured, content of photosynthetic pigments and endogenous hydrogen peroxide (HP) was determined in the leaves. Results. It was established that the effect of chronic UV‑B irradiation caused the temporary inhibition of leaf growth, synthesis of photosynthetic pigments and increasing of HP content in them. Then the growth processes and pigment complex recovered to the level of no irradiated plants and exceed it, indicating the induction of adaptive reactions in young corn plants. Conclusions. It was shown that the effect of a low dose of chronic UV-B irradiation caused a delay in growth processes and the formation of a photosynthetic complex with subsequent adaptation to stress in young corn plants. Keywords: UV-B irradiation, Zea mays L., photosynthetic pigments, adaptation.

A paralog of a bacteriochlorophyll biosynthesis enzyme catalyzes the formation of 1,2-dihydrocarotenoids in green sulfur bacteria

Chlorobaculum tepidum, a green sulfur bacterium, utilizes chlorobactene as its major carotenoid, and this organism also accumulates a reduced form of this monocyclic pigment, 1′,2′-dihydrochlorobactene. The protein catalyzing this reduction is the last unidentified enzyme in the biosynthetic pathways for all of the green sulfur bacterial pigments used for photosynthesis. The genome of C. tepidum contains two paralogous genes encoding members of the FixC family of flavoproteins: bchP, which has been shown to encode an enzyme of bacteriochlorophyll biosynthesis; and bchO, for which a function has not been assigned. Here we demonstrate that a bchO mutant is unable to synthesize 1′,2′-dihydrochlorobactene, and when bchO is heterologously expressed in a neurosporene-producing mutant of the purple bacterium, Rhodobacter sphaeroides, the encoded protein is able to catalyze the formation of 1,2-dihydroneurosporene, the major carotenoid of the only other organism reported to synthesize 1,2-dihydrocarotenoids, Blastochloris viridis. Identification of this enzyme completes the pathways for the synthesis of photosynthetic pigments in Chlorobiaceae, and accordingly and consistent with its role in carotenoid biosynthesis, we propose to rename the gene cruI. Notably, the absence of cruI in B. viridis indicates that a second 1,2-carotenoid reductase, which is structurally unrelated to CruI (BchO), must exist in nature. The evolution of this carotenoid reductase in green sulfur bacteria is discussed herein.

Influence of lead salts on some morphological and physiological parameters of filamentous cyanobacteria

In the conditions of a model laboratory experiment the influence of lead salts (an acetate and nitrate) on morphological and physiological parameters of filamentous cyanobacteria was studied. During the experiment we estimated features of formation of biomass, structure of trichomes, form and the size of cells, content of chlorophyll a, carotenoids and phycobiliproteins. It is noted that in the presence of lead acetate of up to 5 maximum allowable concentrations there is a formation of a biomass in the form of attached and free films, and presence of a nitrate form of lead at the same concentration promotes formation of filaments, fixed from one side. At the same time, the increase of concentration of both acetate, and nitrate forms of lead promotes formation of rarefied films of one layer multidirectional trichomes; to disintegration of trichomes on the fragments and separate cells united by an external mucilaginous envelope. Content of lead acetate in concentration of 15 times the maximum allowable concentration, and lead nitrate at 10 times the maximum allowable concentration leads to formation of abnormally long cells up to 10.0–10.5 µm long. It is established that lead acetate has a stimulating effect on formation of a biomass and synthesis of photosynthetic pigments. The biomass growth of up to 223.7% of the control was observed at concentration up to 15 times the maximum allowable concentration inclusive. The content of chlorophyll a grew by 30.6%, carotenoids – by 24.0% at one maximum allowable concentration. Lead nitrate stimulates a biomass gain much more weakly – up to 70.0% at 5 times the maximum allowable concentration and also has the expressed inhibiting effect on synthesis of photosynthetic pigments. Depression of concentration of chlorophyll a and carotenoids by 38.8% and 79.4% respectively was observed already at one maximum allowable concentration. The stimulating effect of lead acetate is noted on synthesis of phycocyanin (by 94.0%) and allophycocyanin (by 120.0%) in concentration up to 5 times the maximum allowable concentration; the stimulating effect of lead nitrate was observed on synthesis of phycocyanin (by 64.7%) in concentration up to 5 times the maximum allowable concentration and on synthesis of allophycocyanin (up to 140.0%) and on phycoerythrin (up to 228.0%) at concentration up to 10 times the maximum allowable concentration. Comparison of influence of various lead salts on filamentous cyanobacteria revealed a more expressed inhibiting effect of the nitrate form of lead in comparison with acetate.

The adaptability of a wetland plant species Myriophyllum aquaticum to different nitrogen forms and nitrogen removal efficiency in constructed wetlands.

Constructed wetlands (CWs) cultivated with Myriophyllum aquaticum showed great potential for total nitrogen (TN) removal from aquatic ecosystems in previous studies. To evaluate the growth characteristics, photosynthetic pigment content, and antioxidative responses of M. aquaticum, as well as its TN removal efficiency in CWs, M. aquaticum was treated with different levels of ammonium (NH4+) and nitrate (NO3-) for 28days. The results indicated that M. aquaticum had strong nitrogen stress tolerance and was more likely to be suppressed by high levels of NH4+ than NO3-. High levels of NH4+ also led to inhibition of synthesis of photosynthetic pigments and increased peroxidase activity in plant leaves, which was not found in the NO3- treatments. High levels of both NH4+ and NO3- generated obvious oxidative stress through elevation of malondialdehyde content while decreasing superoxide dismutase activity in the early stage. A sustainable increase of TN removal efficiency in most of the CWs indicated that M. aquaticum was a candidate species for treating wastewater with high levels of nitrogen because of its higher tolerance for NH4+ and NO3- stress. However, the increase of TN removal efficiency was hindered in the late stage when treated with high levels of NH4+ of 26 and 36mmol/L, indicating that its tolerance to NH4+ stress might have a threshold. The results of this study will enrich the studies on detoxification of high ammonium ion content in NH4+-tolerant submerged plants and supply valuable reference data for proper vegetation of M. aquaticum in CWs.

Endophytic bacterium Bacillus subtilis (BERA 71) improves salt tolerance in chickpea plants by regulating the plant defense mechanisms

ABSTRACTPlant growth-promoting endophytic bacteria can stimulate the growth, nutrient acquisition, symbiotic performance and stress tolerance of chickpea plants under saline soil conditions. The aim of this study was to investigate the stress-adaptive mechanisms of chickpea plants mediated by Bacillus subtilis (BERA 71) under saline conditions. Inoculation with BERA 71 enhanced plant biomass and the synthesis of photosynthetic pigments and reduced the levels of reactive oxygen species (ROS) and lipid peroxidation in plants under conditions of stress. Furthermore, the activities of ROS-scavenging antioxidant enzymes (superoxide dismutase, peroxidase, catalase and glutathione reductase), the levels of non-enzymatic antioxidants (ascorbic acid and glutathione) and the total phenol content were increased in stressed plants during bacterial association. The bacteria decreased sodium accumulation and enhanced the nitrogen, potassium, calcium and magnesium content in the plants. The suppression of ROS generation and of lipid peroxidation and the accumulation of proline in BERA-71-inoculated plants enhanced the membrane stability under salinity stress and non-stress conditions.

Silicon supplementation modulates antioxidant system and osmolyte accumulation to balance salt stress in Acacia gerrardii Benth.

Experiments were conducted to investigate the role of silicon (Si, 2 mM potassium silicate - K2SiO3) in ameliorating the salinity (200 mM NaCl) triggered growth retardation, photosynthetic inhibition and the oxidative damage in Talh trees (Acacia gerrardii Benth). Salinity stress reduced length and dry biomass accumulation of root and shoot which were significantly improved by Si supplementation. Application of Si enhanced the synthesis of photosynthetic pigments including chlorophyll a, chlorophyll b, total chlorophylls and carotenoids resulting in greater photosynthetic activity measured in terms of net CO2 assimilation. Stomatal conductance and transpiration rate were declined due to NaCl treatment and supplementation of Si ameliorated the negative impact of NaCl on these attributes and was significantly improved when applied to normal grown plants. Further, lipid peroxidation was more in NaCl stressed plants without Si as compared to those supplemented with Si. Si protected Talh trees from NaCl induced oxidative damage by improving the activity of antioxidant enzymes (SOD, POD, CAT, APX and GR) and the content of ascorbic acid. Accumulation of compatible osmolytes including proline and glycine betaine was increased due to Si supplementation leading to improved growth under saline conditions in addition Si supplementation mitigated the deleterious effects of NaCl on flavonoid content. More importantly Si supplementation prevented excess uptake of Na and also protected the ill effects of excess Na on the uptake and accumulation of K and Ca resulting in significant decline in Na/K ratio. In conclusion, Si mitigates the negative effects of NaCl in A. gerrardii by modifying nutrient uptake, osmolytes accumulation and up-regulating antioxidant system.

Specific Distribution of Phosphatidylglycerol to Photosystem Complexes in the Thylakoid Membrane.

The thylakoid membrane is the site of photochemical and electron transport reactions of oxygenic photosynthesis. The lipid composition of the thylakoid membrane, with two galactolipids, one sulfolipid, and one phospholipid, is highly conserved among oxygenic photosynthetic organisms. Besides providing a lipid bilayer matrix, thylakoid lipids are integrated in photosynthetic complexes particularly in photosystems I and II and play important roles in electron transport processes. Thylakoid lipids are differentially allocated to photosynthetic complexes and the lipid bilayer fraction, but distribution of each lipid in the thylakoid membrane is unclear. In this study, based on published crystallographic and biochemical data, we estimated the proportions of photosynthetic complex-associated and bilayer-associated lipids in thylakoid membranes of cyanobacteria and plants. The data suggest that ∼30 mol% of phosphatidylglycerol (PG), the only major phospholipid in thylakoid membranes, is allocated to photosystem complexes, whereas glycolipids are mostly distributed to the lipid bilayer fraction and constitute the membrane lipid matrix. Because PG is essential for the structure and function of both photosystems, PG buried in these complexes might have been selectively conserved among oxygenic phototrophs. The specific and substantial allocation of PG to the deep sites of photosystems may need a unique mechanism to incorporate PG into the complexes possibly in coordination with the synthesis of photosynthetic proteins and pigments.

Urea increased nickel and copper accumulation in the leaves of Egeria densa (Planch.) Casp. and Ceratophyllum demersum L. during short-term exposure

In the present study, two fresh water plant species Egeria densa (Planch.) Casp. and Ceratophyllum demersum L. were subjected to separate and combined action of urea (2mМ) and metals (Ni and Cu, 10μM) to investigate the phytoremediation potential of these two submerged macrophytes during short-term experiments (48h). Both submerged macrophytes demonstrated high accumulative potential for Ni and Cu (average bioconcentration factors were 2505 for Ni and 3778 for Cu). The urea (2 mM) was not significantly toxic for studied plant species. Futhermore, urea worked as an additional source of nitrogen and stimulated some metabolic processes such as the synthesis of photosynthetic pigments, soluble proteins, non-enzymatic antioxidants, and activated some enzymes. Adding urea to the metals increased their accumulation in both macrophytes (on average by 35% for Ni and 15% for Cu). Combined action of urea and Ni did not have a significant effect on antioxidant response, but caused a sharp increase of urease activity (4 folds on an average) in both plants. The copper exerted a stronger toxic effect on both studied macrophytes compared to nickel. Adding urea to copper in some cases diminished the toxic action of this metal. Study concludes that the responses of E. densa and C. demersum to urea and metal action (separate and combined) were depended on the type of pollutant and the activity of antioxidant defence system. Therefore, the studied aquatic macrophytes found to be potential phytoremediators of water bodies, the addition of an organic nitrogen source in the form of urea in environmentally relevant concentration will increase the efficiency of phytoextraction of metals.

Gene mapping and transcriptome profiling of a practical photo-thermo-sensitive rice male sterile line with seedling-specific green-revertible albino leaf

Abnormal environment weather can cause rice photoperiod-thermo-sensitive genic male sterile (PTGMS) lines fertile or partially fertile and thus cause the mixture of true hybrids with selfing seeds. Seedling-specific green-revertible albino leaf color mutant can be used to distinguish the real hybrids. Besides, it can also be used as an ideal material to research the development of chloroplast and biosynthesis of chlorophyll.The phenotype of leaf color mutants includes light green, yellowing, albino, green-revertible albino. Gene mutations affecting the synthesis and degradation of photosynthetic pigments, lycopene and heme, the differentiation and development of chloroplast, gibberellins (GAs) biosynthesis, can change the leaf color.We have created a PTGMS line with seedling-specific green-revertible albino leaf named W01S. The leaf phenotype, pollen sterility and fertility, agronomic traits, heredity, gene mapping and RNA-Seq of the differentially expressed genes between albino and green-revertible leaves were investigated. The results showed that W01S is a practical PTGMS line as Pei’ai 64S. The mutation of candidate gene Os03g0594100 (ent-isokaurene C2-hydroxylase-like) in W01S can be related to the biosynthesis of GAs, indole acetic acids, ethylene.