In vitro selection of microspores for resistance to oxidative stress resulted in chilling tolerance in doubled haploid maize lines

2011 ◽  
Vol 59 (3) ◽  
pp. 209-216
Author(s):  
Eva Darkó ◽  
H. Ambrus ◽  
A. Szenzenstein ◽  
B. Barnabás
Keyword(s):  
Oxidative Stress ◽  
Electron Transport ◽  
Antioxidant Capacity ◽  
Doubled Haploid ◽  
Chilling Stress ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Chilling Tolerance ◽  
Chlorophyll Breakdown ◽  
Induced Changes

The chilling tolerance of doubled haploid (DH) maize plants selected and regenerated from microspores exposed to prooxidants, paraquat or tert-butyl hydroperoxide was determined by monitoring cold-induced changes in the photosynthetic electron transport, CO2 assimilation processes and chlorophyll breakdown in young leaves after cold treatment (8°C for 5 days). The results were compared to those of the non-selected DH line and the original hybrid plants. Chilling stress caused a great reduction in the Fv/Fm, qP and ΔF/Fm’ fluorescence parameters, related to the photosynthetic electron transport processes, and in carbon assimilation, and resulted in chlorophyll breakdown. These changes were less extensive in the selected DH plants, which showed elevated antioxidant capacity both at ambient and at low temperature. Among the antioxidant enzymes tested, the activity of GR and GST was induced by chilling stress to the greatest extent. Correlations between cold-induced changes in the photosynthetic apparatus and the antioxidant capacity of the plants suggested that the better protection against oxidative stress induced by the elevated antioxidant capacity of the plants contributed to protecting the photosynthetic apparatus from cold.

Enhanced Tolerance to Oxidative Stress with Elevated Antioxidant Capacity in Doubled Haploid Maize Derived from Microspores Exposed to Paraquat

Crop Science ◽  
2009 ◽  
Vol 49 (2) ◽  
pp. 628-636 ◽  
Author(s):  
Éva Darkó ◽  
Helga Ambrus ◽  
József Fodor ◽  
Zoltán Király ◽  
Beáta Barnabás
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Capacity ◽  
Doubled Haploid

scholarly journals Flavodiiron proteins act as safety valve for electrons in Physcomitrella patens

2016 ◽  
Vol 113 (43) ◽  
pp. 12322-12327 ◽  
Author(s):  
Caterina Gerotto ◽  
Alessandro Alboresi ◽  
Andrea Meneghesso ◽  
Martina Jokel ◽  
Marjaana Suorsa ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Physcomitrella Patens ◽  
Safety Valve ◽  
Cell Metabolism ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Flowering Plants ◽  
Knock Out ◽  
Electron Sink

Photosynthetic organisms support cell metabolism by harvesting sunlight to fuel the photosynthetic electron transport. The flow of excitation energy and electrons in the photosynthetic apparatus needs to be continuously modulated to respond to dynamics of environmental conditions, and Flavodiiron (FLV) proteins are seminal components of this regulatory machinery in cyanobacteria. FLVs were lost during evolution by flowering plants, but are still present in nonvascular plants such as Physcomitrella patens. We generated P. patens mutants depleted in FLV proteins, showing their function as an electron sink downstream of photosystem I for the first seconds after a change in light intensity. flv knock-out plants showed impaired growth and photosystem I photoinhibition when exposed to fluctuating light, demonstrating FLV’s biological role as a safety valve from excess electrons on illumination changes. The lack of FLVs was partially compensated for by an increased cyclic electron transport, suggesting that in flowering plants, the FLV’s role was taken by other alternative electron routes.

scholarly journals Photosynthesis Regulation in Response to Fluctuating Light in the Secondary Endosymbiont Alga Nannochloropsis gaditana

2019 ◽  
Vol 61 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Alessandra Bellan ◽  
Francesca Bucci ◽  
Giorgio Perin ◽  
Alessandro Alboresi ◽  
Tomas Morosinotto
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Incident Light ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Nannochloropsis Gaditana ◽  
Fluctuating Light ◽  
Light Fluctuations

Abstract In nature, photosynthetic organisms are exposed to highly dynamic environmental conditions where the excitation energy and electron flow in the photosynthetic apparatus need to be continuously modulated. Fluctuations in incident light are particularly challenging because they drive oversaturation of photosynthesis with consequent oxidative stress and photoinhibition. Plants and algae have evolved several mechanisms to modulate their photosynthetic machinery to cope with light dynamics, such as thermal dissipation of excited chlorophyll states (non-photochemical quenching, NPQ) and regulation of electron transport. The regulatory mechanisms involved in the response to light dynamics have adapted during evolution, and exploring biodiversity is a valuable strategy for expanding our understanding of their biological roles. In this work, we investigated the response to fluctuating light in Nannochloropsis gaditana, a eukaryotic microalga of the phylum Heterokonta originating from a secondary endosymbiotic event. Nannochloropsis gaditana is negatively affected by light fluctuations, leading to large reductions in growth and photosynthetic electron transport. Exposure to light fluctuations specifically damages photosystem I, likely because of the ineffective regulation of electron transport in this species. The role of NPQ, also assessed using a mutant strain specifically depleted of this response, was instead found to be minor, especially in responding to the fastest light fluctuations.

Studies on the Mechanism of Copper Toxicity inChlorella

Weed Science ◽  
1974 ◽  
Vol 22 (5) ◽  
pp. 443-449 ◽  
Author(s):  
Arturo Cedeno-Maldonado ◽  
J. A. Swader
Keyword(s):  
Electron Transport ◽  
Photosynthetic Apparatus ◽  
Copper Toxicity ◽  
Photosynthetic Electron Transport ◽  
Autotrophic Growth ◽  
Intact Cells ◽  
Cupric Ion ◽  
High Concentrations ◽  
Short Time ◽  
Photosynthesis And Respiration

Autotrophic growth, photosynthesis, and respiration ofChlorella sorokinianaShihira and Krauss were inhibited by the cupric ion, but photosynthesis was more sensitive than respiration. The percent inhibition was determined by the ratio of cells to cupric ions present. Photosynthesis and respiration were inhibited within 2 and 5 min, respectively, after adding 1.0 mM cupric ions.Chlorellacells which had been incubated for a short time in concentrations of the cupric ion that completely inhibited photosynthesis were not able to grow when cultured in a fresh medium without cupric ions, indicating high concentrations of the ion may have destroyed the photosynthetic apparatus and deprived the cells of their ability for autotrophic growth. Dark preincubation of the cells, as well as high bicarbonate concentrations in the assay medium, decreased inhibition. Treatment with cupric ions reduced the cellular chlorophyll and sulfhydryl content, but anaerobiosis, a condition that increased toxicity, had little effect on the sulfhydryl content. Electron transport in photosystems I and II in intactChlorellacells was inhibited, but the specific sites of inhibition in the photosynthetic electron transport chain could not be determined using intact cells.

scholarly journals Photosynthetic signalling during high light stress and recovery: targets and dynamics

2020 ◽  
Vol 375 (1801) ◽  
pp. 20190406 ◽  
Author(s):  
Peter J. Gollan ◽  
Eva-Mari Aro
Keyword(s):  
Gene Expression ◽  
Electron Transport ◽  
Redox Homeostasis ◽  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
High Light ◽  
Abiotic Stress Response ◽  
High Light Stress ◽  
Retrograde Signalling

The photosynthetic apparatus is one of the major primary sensors of the plant's external environment. Changes in environmental conditions affect the balance between harvested light energy and the capacity to deal with excited electrons in the stroma, which alters the redox homeostasis of the photosynthetic electron transport chain. Disturbances to redox balance activate photosynthetic regulation mechanisms and trigger signalling cascades that can modify the transcription of nuclear genes. H 2 O 2 and oxylipins have been identified as especially prominent regulators of gene expression in response to excess light stress. This paper explores the hypothesis that photosynthetic imbalance triggers specific signals that target discrete gene profiles and biological processes. Analysis of the major retrograde signalling pathways engaged during high light stress and recovery demonstrates both specificity and overlap in gene targets. This work reveals distinct, time-resolved profiles of gene expression that suggest a regulatory interaction between rapidly activated abiotic stress response and induction of secondary metabolism and detoxification processes during recovery. The findings of this study show that photosynthetic electron transport provides a finely tuned sensor for detecting and responding to the environment through chloroplast retrograde signalling. This article is part of the theme issue ‘Retrograde signalling from endosymbiotic organelles’

Abscisic Acid-Induced Chilling Tolerance in Maize Seedlings Is Mediated by Nitric Oxide and Associated with Antioxidant System

2011 ◽  
Vol 378-379 ◽  
pp. 423-427 ◽  
Author(s):  
Hai Yan Li ◽  
Wan Zhong Zhang
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Hydrogen Peroxide ◽  
Lipid Peroxidation ◽  
Abscisic Acid ◽  
Chilling Stress ◽  
Chilling Tolerance ◽  
Maize Seedlings ◽  
No Donor ◽  
Contrary Effect

Abscisic acid (ABA) and sodium nitroprusside (SNP) treatment significantly increased chilling tolerance in maize seedlings. ABA in combination with nitric oxide (NO) donor SNP further enhanced the ABA-induced chilling tolerance. But the addition of NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) nullified the increasing effect of SNP on chilling tolerance. In addition, the combination of ABA and PTIO decreased the ABA-induced chilling tolerance. Measurement of activities of superoxide dismutase (SOD) and catalase (CAT), hydrogen peroxide (H2O2) content and the level of lipid peroxidation (in terms of malondialdehyde) indicated that chilling stress induced an oxidative stress in maize seedlings. ABA treatment enabled maize seedlings to maintain higher SOD and CAT activities and lower level of H2O2 and lipid peroxidation under chilling stress. ABA in combination with SNP further enhanced the ABA-induced increase in SOD and CAT activities and lowered the chilling stress-induced lipid peroxidation in the ABA-treated seedlings. But the addition of PTIO scavenged the increasing effect of SNP. In addition, the combination of ABA and PTIO had a contrary effect with that of ABA and SNP. These results suggest that the ABA-induced chilling tolerance is mediated by NO, NO is involved in ABA-induced chilling tolerance by increasing activities of antioxidant enzymes and reduced endogenous H2O2 accumulation.

scholarly journals Oxidative Stress and Chilling Tolerance in Tomato Seedlings

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 645b-645
Author(s):  
Kanogwan Kerdnaimongkol ◽  
Anju Bhatia ◽  
Robert J. Joly ◽  
William R. Woodson
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Diurnal Variation ◽  
Chilling Stress ◽  
Chilling Injury ◽  
Chilling Tolerance ◽  
Light Period ◽  
Tomato Seedlings ◽  
Chilling Sensitivity

Diurnal variation in the chilling sensitivity of tomato seedlings was examined. Sensitivity to chilling in tomato seedlings is a response to light and not under the control of a circadian rhythm. Chilling sensitivity is highest in seedlings chilled at the end of the dark period, and these seedlings become more resistant to chilling injury upon exposure to the light. Diurnal variation in chilling sensitivity was associated with changes in catalase and superoxide dismutase activities. The results show an increase in catalase and superoxide dismutase activities at the end of the light period. The recovery of the net photosynthesis rate following chilling was faster in seedlings chilled at the end of the light period. It is suggested that an increase in catalase and superoxide dismutase activities at the end of light period before the chilling plays a role in the resistance to chilling stress in tomato seedlings. Forty-eight hours of 14°C acclimation or hydrogen peroxide pretreatment conferred chilling tolerance to tomato seedlings and were correlated with elevated catalase activity. Acclimated seedlings still exhibited diurnal variation in chilling sensitivity while hydrogen peroxide treated seedlings showed little evidence of a diurnal variation in chilling sensitivity. Transgenic tomato plants expressing an antisense catalase gene were generated. A several-fold decrease in total catalase has been detected in the leaf extracts of transformants. Preliminary analysis of these plants indicated that modification of reactive oxygen species scavenging in plant system can lead to change in oxidative stress tolerance.

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