scholarly journals The better growth phenotype of DvGS1-transgenic arabidopsis thaliana is attributed to the improved efficiency of nitrogen assimilation

2015 ◽  
Vol 67 (4) ◽  
pp. 1107-1118
Author(s):  
Chenguang Zhu ◽  
Guimin Zhang ◽  
Shilin Chen ◽  
Wei Wang ◽  
Yuanping Tang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Arabidopsis Thaliana ◽  
Enzymatic Activity ◽  
Carbon Metabolism ◽  
Transgenic Line ◽  
Nitrogen Assimilation ◽  
Transgenic Arabidopsis ◽  
Wild Type ◽  
Leaf Tissues ◽  
Growth Phenotype

The overexpression of the algal glutamine synthetase (GS) gene DvGS1 in Arabidopsis thaliana resulted in higher plant biomass and better growth phenotype. The purpose of this study was to recognize the biological mechanism for the growth improvement of DvGS1-transgenic Arabidopsis. A series of molecular and biochemical investigations related to nitrogen and carbon metabolism in the DvGS1-transgenic line was conducted. Analysis of nitrogen use efficiency (NUE)-related gene transcription and enzymatic activity revealed that the transcriptional level and enzymatic activity of the genes encoding GS, glutamate synthase, glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase, were significantly upregulated, especially from leaf tissues of the DvGS1-transgenic line under two nitrate conditions. The DvGS1-transgenic line showed increased total nitrogen content and decreased carbon: nitrogen ratio compared to wild-type plants. Significant reduced concentrations of free nitrate, ammonium, sucrose, glucose and starch, together with higher concentrations of total amino acids, individual amino acids (glutamate, aspartate, asparagine, methionine), soluble proteins and fructose in leaf tissues confirmed that the DvGS1-transgenic line demonstrated a higher efficiency of nitrogen assimilation, which subsequently affected carbon metabolism. These improved metabolisms of nitrogen and carbon conferred the DvGS1-transgenic Arabidopsis higher NUE, more biomass and better growth phenotype compared with the wild-type plants.

scholarly journals ROS-Scavengers, Osmoprotectants and Violaxanthin De-Epoxidation in Salt-Stressed Arabidopsis thaliana with Different Tocopherol Composition

2021 ◽  
Vol 22 (21) ◽  
pp. 11370
Author(s):  
Ewa Surówka ◽  
Dariusz Latowski ◽  
Michał Dziurka ◽  
Magdalena Rys ◽  
Anna Maksymowicz ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Salt Stress ◽  
Transgenic Line ◽  
Wild Type ◽  
Carbon And Nitrogen ◽  
Nacl Concentration ◽  
Tocopherol Composition ◽  
Ros Scavengers ◽  
Excessive Accumulation

To determine the role of α- and γ-tocopherol (TC), this study compared the response to salt stress (200 mM NaCl) in wild type (WT) Arabidopsis thaliana (L.) Heynh. And its two mutants: (1) totally TC-deficient vte1; (2) vte4 accumulating γ-TC instead of α-TC; and (3) tmt transgenic line overaccumulating α-TC. Raman spectra revealed that salt-exposed α-TC accumulating plants were more flexible in regulating chlorophyll, carotenoid and polysaccharide levels than TC deficient mutants, while the plants overaccumulating γ-TC had the lowest levels of these biocompounds. Tocopherol composition and NaCl concentration affected xanthophyll cycle by changing the rate of violaxanthin de-epoxidation and zeaxanthin formation. NaCl treated plants with altered TC composition accumulated less oligosaccharides than WT plants. α-TC deficient plants increased their oligosaccharide levels and reduced maltose amount, while excessive accumulation of α-TC corresponded with enhanced amounts of maltose. Salt-stressed TC-deficient mutants and tmt transgenic line exhibited greater proline levels than WT plants, lower chlorogenic acid levels, and lower activity of catalase and peroxidases. α-TC accumulating plants produced more methylated proline- and glycine- betaines, and showed greater activity of superoxide dismutase than γ-TC deficient plants. Under salt stress, α-TC demonstrated a stronger regulatory effect on carbon- and nitrogen-related metabolites reorganization and modulation of antioxidant patterns than γ-TC. This suggested different links of α- and γ-TCs with various metabolic pathways via various functions and metabolic loops.

Vein density is independent of epidermal cell size in Arabidopsis mutants

2017 ◽  
Vol 44 (4) ◽  
pp. 410 ◽  
Author(s):  
Madeline R. Carins Murphy ◽  
Graham J. Dow ◽  
Gregory J. Jordan ◽  
Timothy J. Brodribb
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Size ◽  
Epidermal Cell ◽  
Cell Expansion ◽  
Vascular Plants ◽  
Cost Ratio ◽  
Wild Type ◽  
Vein Density ◽  
Leaf Tissues ◽  
Epidermal Cell Size

Densities of leaf minor veins and stomata are co-ordinated within and across vascular plants. This maximises the benefit-to-cost ratio of leaf construction by ensuring stomata receive the minimum amount of water required to maintain optimal aperture. A ‘passive dilution’ mechanism in which densities of veins and stomata are co-regulated by epidermal cell size is thought to facilitate this co-ordination. However, unlike stomata, veins are spatially isolated from the epidermis and thus may not be directly regulated by epidermal cell expansion. Here, we use mutant genotypes of Arabidopsis thaliana (L.) Heynh. with altered stomatal and epidermal cell development to test this mechanism. To do this we compared observed relationships between vein density and epidermal cell size with modelled relationships that assume veins and stomata are passively diluted by epidermal cell expansion. Data from wild-type plants were consistent with the ‘passive dilution’ mechanism, but in mutant genotypes vein density was independent of epidermal cell size. Hence, vein density is not causally linked to epidermal cell expansion. This suggests that adaptation favours synchronised changes to the cell size of different leaf tissues to coordinate veins and stomata, and thus balance water supply with transpirational demand.

Molecular-Genetics of Nitrogen Assimilation into Amino Acids in Arabidopsis thaliana

1994 ◽  
pp. 141-150
Author(s):  
Gloria Coruzzi ◽  
Karen Coschigano ◽  
Hon-Ming Lam ◽  
Rosana Oliveira ◽  
Sheila Peng ◽  
...  
Keyword(s):  
Amino Acids ◽  
Arabidopsis Thaliana ◽  
Molecular Genetics ◽  
Nitrogen Assimilation

scholarly journals Improving the Thermostability of Raw-Starch-Digesting Amylase from a Cytophaga sp. by Site-Directed Mutagenesis

2003 ◽  
Vol 69 (4) ◽  
pp. 2383-2385 ◽  
Author(s):  
Rong-Jen Shiau ◽  
Hui-Chen Hung ◽  
Chii-Ling Jeang
Keyword(s):  
Amino Acids ◽  
Enzymatic Activity ◽  
Half Life ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Wild Type ◽  
Raw Starch ◽  
Heat Stable ◽  
Independent Mechanism

ABSTRACT A heat-stable raw-starch-digesting amylase (RSDA) was generated through PCR-based site-directed mutagenesis. At 65°C, the half-life of this mutant RSDA, which, compared with the wild-type RSDA, lacks amino acids R178 and G179, was increased 20-fold. While the wild type was inactivated completely at pH 3.0, the mutant RSDA still retained 41% of its enzymatic activity. The enhancement of RSDA thermostability was demonstrated to be via a Ca2+-independent mechanism.

scholarly journals The Impact of Photorespiratory Glycolate Oxidase Activity on Arabidopsis thaliana Leaf Soluble Amino Acid Pool Sizes during Acclimation to Low Atmospheric CO2 Concentrations

Metabolites ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 501
Author(s):  
Younès Dellero ◽  
Caroline Mauve ◽  
Mathieu Jossier ◽  
Michael Hodges
Keyword(s):  
Amino Acids ◽  
Arabidopsis Thaliana ◽  
Amino Acid ◽  
Atmospheric Co2 ◽  
Glycolate Oxidase ◽  
Wild Type ◽  
Low Co2 ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations ◽  
The Impact

Photorespiration is a metabolic process that removes toxic 2-phosphoglycolate produced by the oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase. It is essential for plant growth under ambient air, and it can play an important role under stress conditions that reduce CO2 entry into the leaf thus enhancing photorespiration. The aim of the study was to determine the impact of photorespiration on Arabidopsis thaliana leaf amino acid metabolism under low atmospheric CO2 concentrations. To achieve this, wild-type plants and photorespiratory glycolate oxidase (gox) mutants were given either short-term (4 h) or long-term (1 to 8 d) low atmospheric CO2 concentration treatments and leaf amino acid levels were measured and analyzed. Low CO2 treatments rapidly decreased net CO2 assimilation rate and triggered a broad reconfiguration of soluble amino acids. The most significant changes involved photorespiratory Gly and Ser, aromatic and branched-chain amino acids as well as Ala, Asp, Asn, Arg, GABA and homoSer. While the Gly/Ser ratio increased in all Arabidopsis lines between air and low CO2 conditions, low CO2 conditions led to a higher increase in both Gly and Ser contents in gox1 and gox2.2 mutants when compared to wild-type and gox2.1 plants. Results are discussed with respect to potential limiting enzymatic steps with a special emphasis on photorespiratory aminotransferase activities and the complexity of photorespiration.

scholarly journals C Terminus of DJ-1 Determines Its Homodimerization, Deglycation Activity and Suppression of Ferroptosis

2020 ◽  
Author(s):  
Li Jiang ◽  
Xiaobing Chen ◽  
Qian Wu ◽  
Haiying Zhu ◽  
Chengyong Du ◽  
...  
Keyword(s):  
Amino Acids ◽  
Parkinson Disease ◽  
Enzymatic Activity ◽  
Early Onset ◽  
Wild Type ◽  
Functional Protein ◽  
Point Mutant ◽  
C Terminus ◽  
Antioxidative Stress ◽  
The Relationship

AbstractDJ-1 is a multi-functional protein related to cancer and autosomal early-onset Parkinson disease (PD). Besides the well-documented antioxidative stress activity, recent studies suggest that DJ-1 has the deglycation enzymatic activity and the anti-ferroptosis function. Although it has been demonstrated that DJ-1 forms the homodimerization, which dictates its antioxidative stress activity, the relationship between the dimeric structure and newly reported activities remains largely elusive. In this study, we find that the deletion mutation of the last 3 amino acids at C terminus of DJ-1 disrupts its homodimerization in both transfected and purified DJ-1 protein. Further study shows that hydrophobic L187 residue is of great importance for DJ-1 homodimerization. In addition, the ability in methylglyoxal detoxification is almost abolished in the mutation of deleting last 3 residues at C terminus (ΔC3) and point mutant L187E compared with wild type DJ-1 (DJ-1 WT). We also find that the suppression of ferroptosis is fully inhibited by ΔC3 and L187E while partially suppressed by V51C. Thus, our findings show that C terminus of DJ-1 is crucial for its homodimerization, deglycation activity and suppression of ferroptosis.

scholarly journals Light-Independent Nitrogen Assimilation in Plant Leaves: Nitrate Incorporation into Glutamine, Glutamate, Aspartate, and Asparagine Traced by 15N

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1303
Author(s):  
Tadakatsu Yoneyama ◽  
Akira Suzuki
Keyword(s):  
Amino Acids ◽  
Nitrogen Assimilation ◽  
Nitrate Assimilation ◽  
Glutamate Synthase ◽  
Enzymatic Reactions ◽  
Nitrite Reductases ◽  
Leaf Tissues ◽  
Nitrate And Nitrite ◽  
Cellular Compartments ◽  
Donor System

Although the nitrate assimilation into amino acids in photosynthetic leaf tissues is active under the light, the studies during 1950s and 1970s in the dark nitrate assimilation provided fragmental and variable activities, and the mechanism of reductant supply to nitrate assimilation in darkness remained unclear. 15N tracing experiments unraveled the assimilatory mechanism of nitrogen from nitrate into amino acids in the light and in darkness by the reactions of nitrate and nitrite reductases, glutamine synthetase, glutamate synthase, aspartate aminotransferase, and asparagine synthetase. Nitrogen assimilation in illuminated leaves and non-photosynthetic roots occurs either in the redundant way or in the specific manner regarding the isoforms of nitrogen assimilatory enzymes in their cellular compartments. The electron supplying systems necessary to the enzymatic reactions share in part a similar electron donor system at the expense of carbohydrates in both leaves and roots, but also distinct reducing systems regarding the reactions of Fd-nitrite reductase and Fd-glutamate synthase in the photosynthetic and non-photosynthetic organs.

Sign in / Sign up

Export Citation Format

Share Document