Magnesium Chelatase of Hordeum vulgare L. Is Not Activated by Light but Inhibited by Pheophorbide

1997 ◽  
Vol 52 (3-4) ◽  
pp. 144-152 ◽  
Author(s):  
Gerhard Pöpperl ◽  
Ulrike Oster ◽  
Inge Bios ◽  
Wolfhart Rüdiger
Keyword(s):  
Enzyme Activity ◽  
Hordeum Vulgare ◽  
White Light ◽  
Envelope Membrane ◽  
Strong Inhibition ◽  
Hordeum Vulgare L ◽  
Magnesium Chelatase ◽  
Metal Free ◽  
Plastid Envelope

AbstractThe enzyme activity of magnesium chelatase was determined in intact etioplasts of barley (Hordeum vulgare L.) seedlings. Irradiation of isolated plastids with white light for 15 min does not lead to any activation of the enzyme but to a decrease in activity, especially in etioplasts. The enzyme was inhibited by chlorophyllide and zinc pheophorbide only to a certain extent. Strong inhibition was observed with the metal-free pheophorbide (Ki = 0.92 μM) but not with pheophytin or chlorophyll. Penetration of chlorophyllide through the envelope membrane was confirmed by the chlorophyll synthase reaction that occurs in the inner membranes of etioplasts and chloroplasts. The possible role of inhibition of magnesium chelatase by pheophorbide in senescent leaves and tetrapyrrole transport across the plastid envelope are discussed.

Role of Ca 2+ in phenolic compound metabolism of barley ( Hordeum vulgare L.) sprouts under NaCl stress

2019 ◽  
Vol 99 (11) ◽  
pp. 5176-5186 ◽  
Author(s):  
Yan Ma ◽  
Pei Wang ◽  
Ting Zhou ◽  
Zhijie Chen ◽  
Zhenxin Gu ◽  
...  
Keyword(s):  
Hordeum Vulgare ◽  
Phenolic Compound ◽  
Nacl Stress ◽  
Hordeum Vulgare L

scholarly journals QTL Mapping for Enzyme Activity and Thermostability of .BETA.-Amylase in Barley (Hordeum vulgare L.).

2001 ◽  
Vol 51 (2) ◽  
pp. 99-105 ◽  
Author(s):  
Takafumi Kaneko ◽  
Wensheng Zhang ◽  
Hidekazu Takahashi ◽  
Kazutoshi Ito ◽  
Kazuyoshi Takeda
Keyword(s):  
Enzyme Activity ◽  
Hordeum Vulgare ◽  
Qtl Mapping ◽  
Hordeum Vulgare L

scholarly journals Differences in hydrolytic enzyme activity accompany natural variation in mature aleurone morphology in barley (Hordeum vulgare L.)

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Matthew K. Aubert ◽  
Stewart Coventry ◽  
Neil J. Shirley ◽  
Natalie S. Betts ◽  
Tobias Würschum ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Hordeum Vulgare ◽  
Natural Variation ◽  
Hydrolytic Enzyme ◽  
Hordeum Vulgare L

scholarly journals The role of exogenous silicon to mitigate Al2O3 nanoparticle-induced toxicity in barley (Hordeum vulgare L.)

2021 ◽  
Vol 117 (1) ◽  
pp. 1
Author(s):  
Ghader HABIBI ◽  
Maryam SHAHINFAR
Keyword(s):  
Oxidative Stress ◽  
Hordeum Vulgare ◽  
Inductively Coupled Plasma ◽  
Direct Evidence ◽  
Hordeum Vulgare L ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Exogenous Addition ◽  
Al2o3 Nanoparticle

<p>In this study, we used silicon (Si, in the form of K<sub>2</sub>SiO<sub>3</sub>, 2 mM) to alleviate the toxicity of aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) nanoparticles (NPs) in barley (<em>Hordeum vulgare</em> L.). Using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) analyses, we showed that the Al<sub>2</sub>O<sub>3</sub> NPs were taken up by barley plants. Barley growth was negatively affected by the addition of 3 g l<sup>-1</sup> nano-Al<sub>2</sub>O<sub>3</sub>, whereas the diminishing effect of NPs on barley growth was not obvious when 1 g l<sup>-1</sup> nano-Al<sub>2</sub>O<sub>3</sub> was applied, indicating that the nano-Al<sub>2</sub>O<sub>3</sub> action is dependent on nano-Al<sub>2</sub>O<sub>3</sub> dose. Si pretreatment ameliorated toxic effects of high nano-Al<sub>2</sub>O<sub>3</sub> on root growth. Si pretreatment did not decrease nano-Al<sub>2</sub>O<sub>3</sub> entry into roots but reduced nano-Al<sub>2</sub>O<sub>3</sub> accumulation in the shoot. The restriction of the root-to-shoot translocation of nano-Al<sub>2</sub>O<sub>3 </sub>was one of the important mechanisms for Si to mitigate high nano-Al<sub>2</sub>O<sub>3</sub> toxicity. The occurrence of oxidative stress was found under 3 g l<sup>1</sup> nano-Al<sub>2</sub>O<sub>3 </sub>treatment, as evaluated by the accumulation of malondialdehyde (MDA). Exogenous addition of Si could alleviate toxicity symptoms induced by Al<sub>2</sub>O<sub>3</sub> nanoparticles by reducing lipid peroxidation via enhancing antioxidant activity of catalase as well as by limiting the root-to-shoot translocation of nano-Al<sub>2</sub>O<sub>3</sub>. These data provide the first direct evidence that the Si pretreatment ameliorates nano Al<sub>2</sub>O<sub>3</sub> phytotoxicity in plants.</p>

scholarly journals Boron induces seed germination and seedling growth of Hordeum vulgare L. under Nacl stress

2018 ◽  
Vol 8 ◽  
pp. 1224-1234
Author(s):  
Saud A. Alamri ◽  
Manzer H Siddiqui ◽  
Mutahhar Y. Al-Khaishani ◽  
Hayssam M. Ali
Keyword(s):  
Hordeum Vulgare ◽  
Seed Germination ◽  
Seedling Growth ◽  
Growth Traits ◽  
Nacl Stress ◽  
High Dose ◽  
Barley Plant ◽  
Hordeum Vulgare L ◽  
Viable Cells

Boron (B), an essential micronutrient, helps the plants to complete their life cycle successfully. Therefore, the present experiment was conducted to study (1) the role of B in seed germination and seedling growth, (2) the toxicity effect of B in seed germination and seedling growth and (3) the role of B in tolerance of barley (Hordeum vulgare L. var. ‘Bakore’) to NaCl stress. Under NaCl stress and non-stress conditions, application of high levels of B (100 µM) decreased parameters of germination (G%, VI, GI and MGT), growth (RL, SL, RFW, SFW, RDW and SDW), except the accumulation of Pro and MDA in barley seedlings. Also, a fluorescence study reveals that production of ROS (H2O2 and O2 •—) and non-viable cells increased in roots of barley seedlings treated with NaCl and high dose of B. An alteration in anatomical structure of barley seedlings was observed with the application of NaCl and high dose of B. However, a low concentration of B (50 µM) proved best and increased all germination and growth traits of barley seedlings by increasing further accumulation of Pro. Also, 50 µM of B significantly increased the biosynthesis of photosynthetic pigments (Chl a, b and total Chl) and deceased formation of ROS and viable cells in roots. Therefore, concluded that sufficient dose of B could be beneficial for barley plant in improving the tolerance to NaCl stress.

scholarly journals Heterologous Expression of the Barley (Hordeum vulgare L.) Xantha-f, -g and -h Genes that Encode Magnesium Chelatase Subunits

2020 ◽  
Vol 39 (5) ◽  
pp. 554-562
Author(s):  
Rabab Mahdi ◽  
David Stuart ◽  
Mats Hansson ◽  
Helmy M. Youssef
Keyword(s):  
Hordeum Vulgare ◽  
Recombinant Proteins ◽  
Structural Information ◽  
Recombinant Expression ◽  
Expression System ◽  
Protoporphyrin Ix ◽  
Buffer System ◽  
Enzymatic Reactions ◽  
Hordeum Vulgare L ◽  
Magnesium Chelatase

AbstractBiosynthesis of chlorophyll involves several enzymatic reactions of which many are shared with the heme biosynthesis pathway. Magnesium chelatase is the first specific enzyme in the chlorophyll pathway. It catalyzes the formation of Mg-protoporphyrin IX from the insertion of Mg2+ into protoporphyrin IX. The enzyme consists of three subunits encoded by three genes. The three genes are named Xantha-h, Xantha-g and Xantha-f in barley (Hordeum vulgare L.). The products of the genes have a molecular weight of 38, 78 and 148 kDa, respectively, as mature proteins in the chloroplast. Most studies on magnesium chelatase enzymes have been performed using recombinant proteins of Rhodobacter capsulatus, Synechocystis sp. PCC6803 and Thermosynechococcus elongatus, which are photosynthetic bacteria. In the present study we established a recombinant expression system for barley magnesium chelatase with the long-term goal to obtain structural information of this enigmatic enzyme complex from a higher plant. The genes Xantha-h, -g and -f were cloned in plasmid pET15b, which allowed the production of the three subunits as His-tagged proteins in Escherichia coli BL21(DE3)pLysS. The purified subunits stimulated magnesium chelatase activity of barley plastid extracts and produced activity in assays with only recombinant proteins. In preparation for future structural analyses of the barley magnesium chelatase, stability tests were performed on the subunits and activity assays were screened to find an optimal buffer system and pH.

scholarly journals Role of Cystoseira mediterranea extracts (Sauv.) in the Alleviation of salt stress adverse effect and enhancement of some Hordeum vulgare L. (barley) growth parameters

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Leila Bensidhoum ◽  
El-hafid Nabti
Keyword(s):  
Hydrogen Peroxide ◽  
Lipid Peroxidation ◽  
Salt Stress ◽  
Hordeum Vulgare ◽  
Shoot Growth ◽  
Growth Parameters ◽  
Membrane Integrity ◽  
Dry Weight ◽  
Hordeum Vulgare L

AbstractCystoseira mediterranea (Sauv.) extract was tested for its ability to restore barley (Hordeum vulgare) growth under salt stress (350 mM NaCl), shoot growth; membrane integrity; lipid peroxidation and hydrogen peroxide determination were performed. In normal conditions, the obtained data revealed the ability of the extract to stimulate most of barley growth parameters. However, it showed significant effect on most of barley growth parameters (plant height, fresh and dry weight of shoots and roots) and chlorophyll content, under salt stress. The measurement of stress parameters (membrane integrity, lipid peroxidation and hydrogen peroxide) revealed significant effect of C. mediterranea extract on reducing the deleterious impact of salt stress on barley seedlings.

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