scholarly journals Antisense Inhibition of Sorbitol Synthesis Leads to Changes in the Activity of the Antioxidant System in Apple Leaves

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 887E-887
Author(s):  
Rui Zhou* ◽  
Lailiang Cheng ◽  
Abhaya Dandekar
Keyword(s):  
Transgenic Plants ◽  
Antioxidant System ◽  
Developmental Stages ◽  
Reductase Activity ◽  
Physiological Role ◽  
Monodehydroascorbate Reductase ◽  
Antisense Inhibition ◽  
Ros Scavenging ◽  
Fruit Species ◽  
Apple Leaves

Sorbitol is the primary photosynthetic end product in the leaves of many tree fruit species in the Rosaceae family, but its physiological role remains unclear. In this study, we determined the effect of decreased sorbitol synthesis on the antioxidant system that scavenges reactive oxygen species (ROS) in apple leaves. Sorbitol synthesis was decreased in apple leaves by antisense inhibition of aldose-6-phosphate reductase activity. Dehydroascorbate reductase (DHAR), glutathione reductase, and catalase (CAT) activities increased in the leaves of the transgenic plants with decreased sorbitol synthesis, whereas superoxide dismutase, ascorbate peroxidase, NADH dependent and NADPH dependent monodehydroascorbate reductase activity did not show significant changes. Ascorbate and glutathione concentrations were higher in leaves of the transgenic plants compared with the control. The effect of decreased sorbitol synthesis on the antioxidant enzyme activity was dependent on leaf developmental stages. Larger changes in the enzyme activities of CAT, DHAR, and GR were observed in the old leaves than in the young leaves. These results suggest that sorbitol may play a role in ROS scavenging in apple leaves.

scholarly journals Understanding the Role of the Antioxidant System and the Tetrapyrrole Cycle in Iron Deficiency Chlorosis

Plants ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 348 ◽  
Author(s):  
Carla S. Santos ◽  
Rengin Ozgur ◽  
Baris Uzilday ◽  
Ismail Turkan ◽  
Mariana Roriz ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Iron Deficiency ◽  
Antioxidant System ◽  
Reductase Activity ◽  
Activity Levels ◽  
Alkaline Soils ◽  
Ferric Reductase ◽  
Ros Scavenging ◽  
Iron Deficiency Chlorosis ◽  
No Formation

Iron deficiency chlorosis (IDC) is an abiotic stress often experienced by soybean, owing to the low solubility of iron in alkaline soils. Here, soybean lines with contrasting Fe efficiencies were analyzed to test the hypothesis that the Fe efficiency trait is linked to antioxidative stress signaling via proper management of tissue Fe accumulation and transport, which in turn influences the regulation of heme and non heme containing enzymes involved in Fe uptake and ROS scavenging. Inefficient plants displayed higher oxidative stress and lower ferric reductase activity, whereas root and leaf catalase activity were nine-fold and three-fold higher, respectively. Efficient plants do not activate their antioxidant system because there is no formation of ROS under iron deficiency; while inefficient plants are not able to deal with ROS produced under iron deficiency because ascorbate peroxidase and superoxide dismutase are not activated because of the lack of iron as a cofactor, and of heme as a constituent of those enzymes. Superoxide dismutase and peroxidase isoenzymatic regulation may play a determinant role: 10 superoxide dismutase isoenzymes were observed in both cultivars, but iron superoxide dismutase activity was only detected in efficient plants; 15 peroxidase isoenzymes were observed in the roots and trifoliate leaves of efficient and inefficient cultivars and peroxidase activity levels were only increased in roots of efficient plants.

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 A Novel WRKY Transcription Factor from Ipomoea trifida, ItfWRKY70, Confers Drought Tolerance in Sweet Potato

2022 ◽  
Vol 23 (2) ◽  
pp. 686
Author(s):  
Sifan Sun ◽  
Xu Li ◽  
Shaopei Gao ◽  
Nan Nie ◽  
Huan Zhang ◽  
...  
Keyword(s):  
Drought Stress ◽  
Transgenic Plants ◽  
Drought Tolerance ◽  
Sweet Potato ◽  
Stress Responses ◽  
Leaf Tissue ◽  
Stomatal Aperture ◽  
Ros Scavenging ◽  
Ipomoea Trifida ◽  
Positive Role

WRKY transcription factors are one of the important families in plants, and have important roles in plant growth, abiotic stress responses, and defense regulation. In this study, we isolated a WRKY gene, ItfWRKY70, from the wild relative of sweet potato Ipomoea trifida (H.B.K.) G. Don. This gene was highly expressed in leaf tissue and strongly induced by 20% PEG6000 and 100 μM abscisic acid (ABA). Subcellar localization analyses indicated that ItfWRKY70 was localized in the nucleus. Overexpression of ItfWRKY70 significantly increased drought tolerance in transgenic sweet potato plants. The content of ABA and proline, and the activity of SOD and POD were significantly increased, whereas the content of malondialdehyde (MDA) and H2O2 were decreased in transgenic plants under drought stress. Overexpression of ItfWRKY70 up-regulated the genes involved in ABA biosynthesis, stress-response, ROS-scavenging system, and stomatal aperture in transgenic plants under drought stress. Taken together, these results demonstrated that ItfWRKY70 plays a positive role in drought tolerance by accumulating the content of ABA, regulating stomatal aperture and activating the ROS scavenging system in sweet potato.

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.

Enzymatic antioxidant defence mechanisms of maize and sorghum after exposure to and recovery from pre- and post-flowering dehydration

2009 ◽  
Vol 57 (4) ◽  
pp. 445-459 ◽  
Author(s):  
A. Takele ◽  
J. Farrant
Keyword(s):  
Antioxidant System ◽  
Developmental Stages ◽  
Antioxidant Activities ◽  
Limiting Factor ◽  
Enzymatic Antioxidants ◽  
Antioxidant Protection ◽  
Protection Mechanism ◽  
Enzymatic Antioxidant ◽  
Mda Content ◽  
Sorghum Production

Drought stress is often the most limiting factor for maize and sorghum production in the semi-arid areas. This study evaluates the enzymatic antioxidant protection mechanism response of maize (cv Melkassa-2) and sorghum (cv. Macia) after exposure to and recovery from pre- and post-flowering dehydration.The response of enzymatic antioxidant protection systems revealed that in both test crops dehydration during both the pre- and post-flowering stages resulted in increased activities of enzymatic antioxidant protection mechanisms (SOD, GR, CAT and APX). There were, however, differences between the species in the type and extent of enhanced developmentally-induced and dehydration-induced antioxidant activities. Differences were also noticed in the relative water contents at which changes in enzymatic antioxidant activities occurred. Under dehydration conditions, sorghum was generally found to have relatively higher enzymatic antioxidant activities, providing it better protection against oxidative stress by minimizing the level of lipid peroxidation.Lipid peroxidation, measured as MDA content, was increased in both species during pre- and post-flowering dehydration, but the increase was greater in maize than in sorghum during both developmental stages. Sorghum appeared to be able to reduce MDA on rehydration, but maize contained only 85% less MDA after rehydration as compared to the control following pre-flowering rehydration. During post-flowering rehydration, neither species was able to decrease the MDA content to the control level.The results indicated that tolerance to drought in sorghum is well associated with the consistent enhanced capacity of the enzymatic antioxidant system under both pre- and post-flowering dehydration conditions, and that the sensitivity of maize to drought is linearly correlated to the decreased capacity of the antioxidant system. It may be concluded that, since differences were observed between the species in the response of enzymatic antioxidants to pre- and post-flowering dehydration/rehydration, with sorghum exhibiting comparatively higher overall activities of enzymatic antioxidants and a lower level of MDA than maize during both pre- and post-flowering dehydration, selection based on these criteria may help in the development of genotypes tolerant to dehydration.

scholarly journals Characterization of membrane polypeptides from pea leaf peroxisomes involved in superoxide radical generation

1999 ◽  
Vol 337 (3) ◽  
pp. 531-536 ◽  
Author(s):  
Eduardo LÓPEZ-HUERTAS ◽  
Francisco J. CORPAS ◽  
Luisa M. SANDALIO ◽  
Luis A. DEL RÍO
Keyword(s):  
Cytochrome C ◽  
Electron Donor ◽  
Polyclonal Antibodies ◽  
Reductase Activity ◽  
Monodehydroascorbate Reductase ◽  
Peroxisomal Membrane ◽  
Cytochrome C Reductase ◽  
Ferricyanide Reductase ◽  
Sds Page ◽  
O2 Production

The production of superoxide radicals (O2-•) and the activities of ferricyanide reductase and cytochrome c reductase were investigated in peroxisomal membranes from pea (Pisum sativum L.) leaves using NADH and NADPH as electron donors. The generation of O2-• by peroxisomal membranes was also assayed in native polyacrylamide gels using an in situ staining method with NitroBlue Tetrazolium (NBT). When peroxisomal membranes were assayed under native conditions using NADH or NADPH as inducer, two different O2-•-dependent Formazan Blue bands were detected. Analysis by SDS/PAGE of these bands demonstrated that the NADH-induced NBT reduction band contained several polypeptides (PMP32, PMP61, PMP56 and PMP18, where PMP is peroxisomal membrane polypeptide and the number indicates molecular mass in kDa), while the NADPH-induced band was due exclusively to PMP29. PMP32 and PMP29 were purified by preparative SDS/PAGE and electroelution. Reconstituted PMP29 showed cytochrome c reductase activity and O2-• production, and used NADPH specifically as electron donor. PMP32, however, had ferricyanide reductase and cytochrome c reductase activities, and was also able to generate O2-• with NADH as electron donor, whereas NADPH was not effective as an inducer. The reductase activities of, and O2-• production by, PMP32 were inhibited by quinacrine. Polyclonal antibodies against cucumber monodehydroascorbate reductase (MDHAR) recognized PMP32, and this polypeptide is likely to correspond to the MDHAR reported previously in pea leaf peroxisomal membranes.

scholarly journals Identification and Allelic Variation of Genes Involved in the Potato Glycoalkaloid Biosynthetic Pathway

2012 ◽  
Author(s):  
Idit Ginzberg ◽  
Richard E. Veilleux ◽  
James G. Tokuhisa
Keyword(s):  
Transgenic Plants ◽  
Candidate Genes ◽  
Biosynthetic Pathway ◽  
Developmental Stages ◽  
Allelic Variation ◽  
Mevalonic Acid ◽  
Transcript Abundance ◽  
Primary Metabolism ◽  
E Coli ◽  
Isoprenoid Pathway

Steroidal glycoalkaloids (SGAs) are secondary metabolites being part of the plant defense response. The two major SGAs in cultivated potato (Solanum tuberosum) are α-chaconine and α-solanine, which exhibit strong cellular lytic properties and inhibit acetylcholinesterase activity, and are poisonous at high concentrations for humans. As SGAs are not destroyed during cooking and frying commercial cultivars have been bred to contain low levels, and their content in tubers should not exceed 20 mg/100 g fresh weight. However, environmental factors can increase tuber SGA content above the safe level. The focus of the proposed research was to apply genomic approaches to identify candidate genes that control potato SGA content in order to develop tools for potato improvement by marker-assisted selection and/or transgenic approaches. To this end, the objectives of the proposal included identification of genes, metabolic intermediates and allelic variations in the potato SGAbiosynthetic pathway.   The SGAs are biosynthesized by the sterol branch of the mevalonic acid/isoprenoid pathway. Transgenic potato plants that overexpress 3-hydroxy-3-methylglutaryl-CoA reductase 1 (HMG1) or squalene synthase 1 (SQS1), key enzymes of the mevalonic acid/isoprenoid pathway, exhibited elevated levels of solanine and chaconine as well as induced expression of genes downstream the pathway. These results suggest of coordinated regulation of isoprenoid (primary) metabolism and SGA secondary metabolism. The transgenic plants were further used to identify new SGA-related candidate genes by cDNA-AFLP approach and a novel glycosyltransferase was isolated. In addition, genes involved in phytosterol biosynthesis may have dual role and synthesize defense-related steroidal metabolites, such as SGAs, via lanosterol pathway. Potato lanosterol synthase sequence (LAS) was isolated and used to prepare transgenic plants with overexpressing and silencing constructs. Plants are currently being analyzed for SGA content.   The dynamics of SGA accumulation in the various organs of a potato species with high SGA content gave insights into the general regulation of SGA abundance. Leaf SGA levels in S. chacoense were 10 to 20-fold greater than those of S. tuberosum. The leptines, SGAs with strong antifeedant properties against Colorado potato beetles, were present in all aerial tissues except for early and mid-developmental stages of above ground stolons, and accounted for the high SGA content of S. chacoense. These results indicate the presence of regulatory mechanisms in most tissues except in stolons that limit the levels of α-solanine and α-chaconine and confine leptine accumulation to the aerial tissues.   The genomes of cultivated and wild potato contain a 4-member gene family coding for SQS. Three orthologs were cloned as cDNAs from S. chacoense and heterologously expressed in E. coli. Squalene accumulated in all E. coli lines transformed with each of the three gene constructs. Differential transcript abundance in various organs and amino acid sequence differences in the conserved domains of three isoenzymes indicate subfunctionalization of SQS activity and triterpene/sterol metabolism.   Because S. chacoense and S. phureja differ so greatly for presence and accumulation of SGAs, we selected four candidate genes from different points along the biosynthetic pathway to determine if chcor phuspecific alleles were associated with SGA expression in a segregating interspecific diploid population. For two of the four genes (HMG2 and SGT2) F2 plants with chcalleles expressed significantly greater total SGAs compared with heterozygotes and those with phualleles. Although there are other determinants of SGA biosynthesis and composition in potato, the ability of allelic states at two genes to affect SGA levels confirms some of the above transgenic work where chcalleles at two other loci altered SGA expression in Desiree.   Present results reveal new opportunities to manipulate triterpene/sterol biosynthesis in more targeted ways with the objective of altering SGA content for both human health concerns and natural pesticide content without disrupting the essential metabolism and function of the phytosterol component of the membranes and the growth regulating brassinosteroids.

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