scholarly journals Suppression of the Lycopene Cyclase Gene Causes Downregulation of Ascorbate Peroxidase Activity and Decreased Glutathione Pool Size, Leading to H2O2 Accumulation in Euglena gracilis

2021 ◽  
Vol 12 ◽  
Author(s):  
Shun Tamaki ◽  
Ryosuke Sato ◽  
Yuki Koshitsuka ◽  
Masashi Asahina ◽  
Yutaka Kodama ◽  
...  
Keyword(s):  
Ascorbate Peroxidase ◽  
Euglena Gracilis ◽  
Pool Size ◽  
Fluorescent Imaging ◽  
Monodehydroascorbate Reductase ◽  
Ros Scavenging ◽  
Lycopene Cyclase ◽  
Carotenoid Synthesis ◽  
Glutathione Cycle ◽  
Β Carotene

Carotenoids are photosynthetic pigments and hydrophobic antioxidants that are necessary for the survival of photosynthetic organisms, including the microalga Euglena gracilis. In the present study, we identified an uncharacterized gene encoding the E. gracilis β-carotene synthetic enzyme lycopene cyclase (EgLCY) and discovered a relationship between EgLCY-mediated carotenoid synthesis and the reactive oxygen species (ROS) scavenging system ascorbate-glutathione cycle. The EgLCY cDNA sequence was obtained via homology searching E. gracilis transcriptome data. An enzyme assay using Escherichia coli demonstrated that EgLCY converts lycopene to β-carotene. E. gracilis treated with EgLCY double-stranded RNA (dsRNA) produced colorless cells with hypertrophic appearance, inhibited growth, and marked decrease in carotenoid and chlorophyll content, suggesting that EgLCY is essential for the synthesis of β-carotene and downstream carotenoids, which are abundant and physiologically functional. In EgLCY dsRNA-treated cells, the ascorbate-glutathione cycle, composed of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR), and glutathione reductase (GR), was unusually modulated; APX and GR activities significantly decreased, whereas DHAR and MDAR activities increased. Ascorbate content was significantly increased and glutathione content significantly decreased in EgLCY dsRNA-treated cells and was correlated with their recycling enzyme activities. Fluorescent imaging demonstrated that EgLCY dsRNA-treated cells accumulated higher levels of H2O2 compared to wild-type cells. Taken together, this study revealed that EgLCY-mediated synthesis of β-carotene and downstream carotenoid species upregulates APX activity and increases glutathione pool size for H2O2 scavenging. Our study suggests a possible relationship between carotenoid synthesis and the ascorbate-glutathione cycle for ROS scavenging in E. gracilis.

scholarly journals Exposure of the Shaded Side of Apple Fruit to Full Sun Leads to Up-regulation of Both the Xanthophyll Cycle and the Ascorbate-glutathione Cycle

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 887A-887 ◽  
Author(s):  
Feng wang Ma ◽  
Lailiang Cheng*
Keyword(s):  
Xanthophyll Cycle ◽  
Sun Exposure ◽  
Pool Size ◽  
Monodehydroascorbate Reductase ◽  
Enzymatic Antioxidants ◽  
The Sun ◽  
Fruit Peel ◽  
Photosystem Ii Efficiency ◽  
Control Fruit ◽  
Glutathione Cycle

About 80 days after full bloom, well-exposed fruit on the south part of the canopy of mature Liberty/M.9 apple trees were randomly assigned to one of the following two treatments. Some fruit were turned about 180 degrees to expose the original shaded side to full sun whereas the rest served as untreated controls. On day 0, 1, 2, 4, 7, and 10 after treatment, fruit peel samples were taken from the original shaded side of the treated fruit and both the sun-exposed side and the shaded side of the control fruit at midday to determine photosynthetic pigments and enzymatic and non-enzymatic antioxidants. Maximum photosystem II efficiency of the original shaded side decreased sharply after 1 day exposure to full sun, and then gradually recovered to a similar value of the sun-exposed side of the control fruit by day 10. The shaded side of the control fruit had much lower xanthophyll cycle pool size and conversion and antioxidant enzymes and soluble antioxidants of the ascorbate-glutathione cycle than the sun-exposed side. In response to full sun exposure, xanthophyll cycle pool size of the original shaded side increased, reaching a similar value of the sun-exposed side by day 10. Ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase and total pool size and reduction state of both ascorbate and glutathione of the original shaded side all increased to the corresponding values found in the sun-exposed side of the control fruit over a 10-day period. It is concluded that both xanthophyll cycle and the ascorbate-glutathione cycle in the original shaded side are up-regulated in response to fullsun exposure to minimize photo-oxidative damage and contributes to its re-acclimation to full sun.

scholarly journals Combined Production of Astaxanthin and β-Carotene in a New Strain of the Microalga Bracteacoccus aggregatus BM5/15 (IPPAS C-2045) Cultivated in Photobioreactor

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 643
Author(s):  
Konstantin Chekanov ◽  
Daniil Litvinov ◽  
Tatiana Fedorenko ◽  
Olga Chivkunova ◽  
Elena Lobakova
Keyword(s):  
Bubble Column ◽  
Biomass Accumulation ◽  
Natural Antioxidants ◽  
Gas Chromatography Mass Spectrometry ◽  
Stage Scheme ◽  
Green Microalga ◽  
Animal Feeding ◽  
Carotenoid Synthesis ◽  
Bubble Column Photobioreactor ◽  
Β Carotene

Carotenoids astaxanthin and β-carotene are widely used natural antioxidants. They are key components of functional food, cosmetics, drugs and animal feeding. They hold leader positions on the world carotenoid market. In current work, we characterize the new strain of the green microalga Bracteacoccus aggregatus BM5/15 and propose the method of its culturing in a bubble-column photobioreactor for simultaneous production of astaxanthin and β-carotene. Culture was monitored by light microscopy and pigment kinetics. Fatty acid profile was evaluated by tandem gas-chromatography–mass spectrometry. Pigments were obtained by the classical two-stage scheme of autotrophic cultivation. At the first, vegetative, stage biomass accumulation occurred. Maximum specific growth rate and culture productivity at this stage were 100–200 mg∙L−1∙day−1, and 0.33 day−1, respectively. At the second, inductive, stage carotenoid synthesis was promoted. Maximal carotenoid fraction in the biomass was 2.2–2.4%. Based on chromatography data, astaxanthin and β-carotene constituted 48 and 13% of total carotenoid mass, respectively. Possible pathways of astaxanthin synthesis are proposed based on carotenoid composition. Collectively, a new strain B. aggregatus BM5/15 is a potential biotechnological source of two natural antioxidants, astaxanthin and β-carotene. The results give the rise for further works on optimization of B. aggregatus cultivation on an industrial scale.

scholarly journals Trehalose Protects Maize Plants from Salt Stress and Phosphorus Deficiency

Plants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 568
Author(s):  
Md. Motiar Rohman ◽  
Md. Robyul Islam ◽  
Mahmuda Binte Monsur ◽  
Mohammad Amiruzzaman ◽  
Masayuki Fujita ◽  
...  
Keyword(s):  
Glutathione Peroxidase ◽  
Root Length ◽  
Phosphorus Deficiency ◽  
Monodehydroascorbate Reductase ◽  
Maize Seedlings ◽  
Combined Stress ◽  
Ros Scavenging ◽  
Sod Activity ◽  
Maize Varieties ◽  
Hybrid Maize

This study is undertaken to elucidate the role of trehalose (Tre) in mitigating oxidative stress under salinity and low P in maize. Eight-day-old maize seedlings of two maize varieties, BARI Hybrid Maize-7 and BARI Hybrid Maize-9, were subjected to salinity (150 mM NaCl), low P (5 µM KH2PO4) and their combined stress with or without 10 mM Tre for 15 d. Salinity and combined stress significantly inhibited the shoot length, root length, and root volume, whereas low P increased the root length and volume in both genotypes. Exogenous Tre in the stress treatments increased all of the growth parameters as well as decreased the salinity, low P, and combined stress-mediated Na+/K+, reactive oxygen species (ROS), malondialdehyde (MDA), lipoxygenase (LOX) activity, and methylglyoxal (MG) in both genotypes. Individually, salinity and low P increased superoxide dismutase (SOD) activity in both genotypes, but combined stress decreased the activity. Peroxidase (POD) activity increased in all stress treatments. Interestingly, Tre application enhanced the SOD activity in all the stress treatments but inhibited the POD activity. Both catalase (CAT) and glutathione peroxidase (GPX) activity were increased by saline and low P stress while the activities inhibited in combined stress. Similar results were found for ascorbate peroxidase (APX), glutathione peroxidase (GR), and dehydroascorbate reductase (DHAR) activities in both genotypes. However, monodehydroascorbate reductase (MDHAR) activity was inhibited in all the stresses. Interestingly, Tre enhanced CAT, APX, GPX, GR, MDHAR, and DHAR activities suggesting the amelioration of ROS scavenging in maize under all the stresses. Conversely, increased glyoxalase activities in saline and low P stress in BHM-9 suggested better MG detoxification system because of the down-regulation of glyoxalase-I (Gly-I) activity in BHM-7 in those stresses. Tre also increased the glyoxalase activities in both genotypes under all the stresses. Tre improved the growth in maize seedlings by decreasing Na+/K+, ROS, MDA, and MG through regulating antioxidant and glyoxalase systems.

scholarly journals Functional Lycopene Cyclase (CruA) in Cyanobacterium, Arthrospira platensis NIES-39, and its Role in Carotenoid Synthesis

2017 ◽  
Vol 58 (4) ◽  
pp. 831-838 ◽  
Author(s):  
Kenjiro Sugiyama ◽  
Masashi Ebisawa ◽  
Masaharu Yamada ◽  
Yoshiki Nagashima ◽  
Hideyuki Suzuki ◽  
...  
Keyword(s):  
Arthrospira Platensis ◽  
Lycopene Cyclase ◽  
Carotenoid Synthesis

scholarly journals Supplemental Selenium and Boron Mitigate Salt-Induced Oxidative Damages in Glycine max L.

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2224
Author(s):  
Mira Rahman ◽  
Khussboo Rahman ◽  
Khadeja Sultana Sathi ◽  
Md. Mahabub Alam ◽  
Kamrun Nahar ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Salt Stress ◽  
Antioxidant Defense ◽  
Foliar Application ◽  
Growth Parameters ◽  
Monodehydroascorbate Reductase ◽  
Ros Scavenging ◽  
H2o2 Content ◽  
Mda Content ◽  
Different Levels

The present investigation was executed with an aim to evaluate the role of exogenous selenium (Se) and boron (B) in mitigating different levels of salt stress by enhancing the reactive oxygen species (ROS) scavenging, antioxidant defense and glyoxalase systems in soybean. Plants were treated with 0, 150, 300 and 450 mM NaCl at 20 days after sowing (DAS). Foliar application of Se (50 µM Na2SeO4) and B (1 mM H3BO3) was accomplished individually and in combined (Se+B) at three-day intervals, at 16, 20, 24 and 28 DAS under non-saline and saline conditions. Salt stress adversely affected the growth parameters. In salt-treated plants, proline content and oxidative stress indicators such as malondialdehyde (MDA) content and hydrogen peroxide (H2O2) content were increased with the increment of salt concentration but the relative water content decreased. Due to salt stress catalase (CAT), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glyoxalase I (Gly I) and glyoxalase II (Gly II) activity decreased. However, the activity of ascorbate peroxidase (APX), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione S-transferase (GST) and peroxidase (POD) increased under salt stress. On the contrary, supplementation of Se, B and Se+B enhanced the activities of APX, MDHAR, DHAR, GR, CAT, GPX, GST, POD, Gly I and Gly II which consequently diminished the H2O2 content and MDA content under salt stress, and also improved the growth parameters. The results reflected that exogenous Se, B and Se+B enhanced the enzymatic activity of the antioxidant defense system as well as the glyoxalase systems under different levels of salt stress, ultimately alleviated the salt-induced oxidative stress, among them Se+B was more effective than a single treatment.

Physiological, anatomical and antioxidant responses to salinity in the Mediterranean pastoral grass plant Stipa lagascae

2017 ◽  
Vol 68 (9) ◽  
pp. 872 ◽  
Author(s):  
Raoudha Abdellaoui ◽  
Fayçal Boughalleb ◽  
Zohra Chebil ◽  
Maher Mahmoudi ◽  
Azaiez Ouled Belgacem
Keyword(s):  
Glutathione Reductase ◽  
Ascorbate Peroxidase ◽  
Osmotic Adjustment ◽  
Perennial Grass ◽  
Soluble Sugars ◽  
Ros Scavenging ◽  
Total Soluble Sugars ◽  
Chlorophyll Pigments ◽  
Moderate Salinity ◽  
Stipa Lagascae

Soil and water salinity is a major environmental problem in the dry Mediterranean regions, affecting rangeland production. This study investigated the effects of salinity on the wild perennial grass (Poaceae) species Stipa lagascae R. & Sch., a potential forage plant that could be used to rehabilitate degraded rangelands in dry areas. In a laboratory, 3-month-old S. lagascae seedlings were subjected to increasing salt treatments (0–400 mm NaCl) for 45 days. Physiological and biochemical parameters such as leaf water potential (Ψw), leaf relative water content (RWC), proline, total soluble sugars, Na+, K+ and Ca2+ contents, and catalase, ascorbate peroxidase and glutathione reductase activities were measured. Total soluble sugars and proline concentrations increased and Ψw and RWC decreased with increasing salt concentrations. Lower salt concentrations induced a non-significant degradation of chlorophyll pigments. Shoot Na+ content increased with a salinity level, whereas shoot K+ and Ca2+ concentrations decreased and the K+ : Na+ ratio was lower. The salinity threshold, above which S. lagascae showed signs of damage, occurred at 300 mm. Plants have evolved reactive oxygen species (ROS) scavenging enzymes including catalase, ascorbate peroxidase and glutathione reductase, which provide cells with an efficient mechanism to neutralise ROS. The tolerance strategies of S. lagascae to moderate salinity seem to include osmotic adjustment through total soluble sugars and proline accumulation, and highly inducible antioxidative defence. Further investigations are necessary to study the effect of salt stress on distribution of ions (Na+, K+, Ca2+, Mg2+, Cl–, NO3–, SO42–) and osmotic adjustment. Photosynthesis and water-use efficiency parameters could be also useful tools.

Melatonin synthesis enzymes interact with ascorbate peroxidase to protect against oxidative stress in cassava

2020 ◽  
Vol 71 (18) ◽  
pp. 5645-5655 ◽  
Author(s):  
Yujing Bai ◽  
Jingru Guo ◽  
Russel J Reiter ◽  
Yunxie Wei ◽  
Haitao Shi
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Capacity ◽  
Stress Tolerance ◽  
Ascorbate Peroxidase ◽  
Stress Responses ◽  
Direct Interaction ◽  
Ros Scavenging ◽  
Melatonin Synthesis

Abstract Melatonin is an important indole amine hormone in animals and plants. The enzymes that catalyse melatonin synthesis positively regulate plant stress responses through modulation of the accumulation of reactive oxygen species (ROS). However, the relationship between melatonin biosynthetic enzymes and ROS-scavenging enzymes has not been characterized. In this study, we demonstrate that two enzymes of the melatonin synthesis pathway in Manihot esculenta (MeTDC2 and MeASMT2) directly interact with ascorbate peroxidase (MeAPX2) in both in vitro and in vivo experiments. Notably, in the presence of MeTDC2 and MeASMT2, MeAPX2 showed significantly higher activity and antioxidant capacity than the purified MeAPX2 protein alone. These findings indicate that MeTDC2–MeAPX2 and MeASMT2–MeAPX2 interactions both activate APX activity and increase antioxidant capacity. In addition, the combination of MeTDC2, MeASMT2, and MeAPX2 conferred improved resistance to hydrogen peroxide in Escherichia coli. Moreover, this combination also positively regulates oxidative stress tolerance in cassava. Taken together, these findings not only reveal a direct interaction between MeTDC2, MeASMT2, and MeAPX2, but also highlight the importance of this interaction in regulating redox homoeostasis and stress tolerance in cassava.

Biosynthese von Carotinoiden bei Chlorella

1957 ◽  
Vol 12 (6) ◽  
pp. 401-407 ◽  
Author(s):  
Hedwig Claes
Keyword(s):  
Chlorophyll Synthesis ◽  
Mutant Strains ◽  
Carotenoid Synthesis ◽  
Β Carotene ◽  
Carotene Synthesis

One of the recently described mutant strains of chlorella (strain 5/520) accumulates -in the dark phytoene, phytofluene, ζ-carotene, protetrahydrolycopene and prolycopene and forms α- and β-carotene, xanthophylls and appreciable amounts of chlorophyll in light only 1, 2.The experiments described below indicate that1. O2 and light are indispensable for xanthophyll and appreciable chlorophyll synthesis. Both syntheses appear to be linked somehow.2. Carotene synthesis depends upon light but not on O2 and is not linked to xanthophyll synthesis.3. Carotenoid synthesis in light is always accompanied by a decrease of polyenes of the Porter-Lincoln sequence, which have been accumulated in the cells during previous cultivation in the dark. Evidence seems strong that these polyenes are direct precursors of the normal carotenoids.4. An as yet unidentified carotene is formed in appreciable amounts along with the normal carotenes in the light, probably as byproduct, not a precursor.

Ascorbate and glutathione metabolism during development and desiccation of orthodox and recalcitrant seeds of the genus Acer

2007 ◽  
Vol 34 (7) ◽  
pp. 601 ◽  
Author(s):  
Stanislawa Pukacka ◽  
Ewelina Ratajczak
Keyword(s):  
Reactive Oxygen Species ◽  
Desiccation Tolerance ◽  
Reactive Oxygen ◽  
Redox Status ◽  
Seed Maturation ◽  
Monodehydroascorbate Reductase ◽  
Acer Pseudoplatanus ◽  
Oxygen Species ◽  
Norway Maple ◽  
Glutathione Cycle

The ascorbate–glutathione system was studied during development and desiccation of seeds of two Acer species differing in desiccation tolerance: Norway maple (Acer platanoides L., orthodox) and sycamore (Acer pseudoplatanus L., recalcitrant). The results showed remarkable differences in the concentration and redox balance of ascorbate and glutathione between these two kinds of seeds during development, and a significant dependence between glutathione content and acquisition of desiccation tolerance in Norway maple seeds. There were relatively small differences between the species in the activities of enzymes of the ascorbate–glutathione cycle: ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MR, EC 1.6.5.4), dehydroascorbate reductase (DHAR, EC 1.8.5.1), and glutathione reductase (GR, EC 1.6.4.2). At the end of seed maturation, ascorbic acid content and the activities of the above enzymes was about the same in both species The electrophoretic pattern of APX isoenzymes was also similar for both species, and the intensity of the bands decreased at the end of seed maturation in both species. When sycamore seeds were desiccated to a moisture content of less than 26%, there was a marked decrease in seed viability and an increase in the production of reactive oxygen species. During desiccation, Norway maple seeds had a more active defence system, which was reflected in a higher glutathione content, a higher glutathione redox status, a higher ascorbate redox status, and higher activities of APX, MR, DHAR, GR and GPX (glutathione peroxidase). During desiccation, sulfhydryl-to-disulfide transition into proteins was more intense in Norway maple seeds than sycamore seeds. All of these results suggest that, in orthodox seeds, the ascorbate–glutathione cycle plays an important role in the acquisition of tolerance to desiccation, in protein maturation, and in protection from reactive oxygen species.

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