Genetic variation in Fe toxicity tolerance is associated with the regulation of translocation and chelation of iron along with antioxidant defence in shoots of rice

2016 ◽  
Vol 43 (11) ◽  
pp. 1070 ◽  
Author(s):  
Ahmad Humayan Kabir ◽  
Most Champa Begum ◽  
Ariful Haque ◽  
Ruhul Amin ◽  
A. M. Swaraz ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Growth Parameters ◽  
Reductase Activity ◽  
Total Soluble Protein ◽  
Antioxidant Defence ◽  
Excess Iron ◽  
Antioxidant Metabolites ◽  
Fe Toxicity ◽  
Excess Fe ◽  
Chelation Of Iron

Excess iron (Fe) is phytotoxic and causes reduced growth and productivity in rice. In this study we elucidated the mechanisms conferring differential tolerance to Fe-toxicity in rice seedlings. Excess Fe caused retardation in roots of both Pokkali and BRRI 51, but it caused no significant changes on growth parameters, Fe accumulation and OsIRT1 expression in shoots of Pokkali only compared with control plants. These results suggest that the Pokkali genotype does have mechanisms in shoots to withstand Fe toxicity. Pokkali maintained membrane stability and total soluble protein in shoots due to Fe toxicity, further confirming its ability to tolerate excess Fe. Furthermore, a significant decrease of Fe-chelate reductase activity and OsFRO1 expression in shoots of Pokkali suggests that limiting Fe accumulation is possibly regulated by Fe-reductase activity. Our extensive expression analysis on the expression pattern of three chelators (OsDMAS1, OsYSL15, OsYSL2 and OsFRDL1) showed no significant changes in expression in shoots of Pokkali due to Fe toxicity, whereas these genes were significantly upregulated under Fe-toxicity in sensitive BRRI 51. These results imply that regulation of Fe chelation in shoots of Pokkali contributes to its tolerance to Fe toxicity. Finally, increased catalase (CAT), peroxidase (POD), glutathione reductase (GR) and superoxide dismutase (SOD), along with elevated ascorbic acid, glutathione, cysteine, methionine and proline in shoots of Pokkali caused by Fe toxicity suggests that strong antioxidant defence protects rice plants from oxidative injury under Fe toxicity. Taking these results together, we propose that genetic variation in Fe-toxicity tolerance in rice is shoot based, and is mainly associated with the regulation of translocation and chelation of Fe together with elevated antioxidant metabolites in shoots.

scholarly journals How Does Rice Defend Against Excess Iron?: Physiological and Molecular Mechanisms

2020 ◽  
Vol 11 ◽  
Author(s):  
May Sann Aung ◽  
Hiroshi Masuda
Keyword(s):  
Molecular Mechanisms ◽  
Low Ph ◽  
Ion Concentration ◽  
Growth And Yield ◽  
Association Analyses ◽  
Excess Iron ◽  
Fe Uptake ◽  
Fe Toxicity ◽  
Fe Excess ◽  
Excess Fe

Iron (Fe) is an essential nutrient for all living organisms but can lead to cytotoxicity when present in excess. Fe toxicity often occurs in rice grown in submerged paddy fields with low pH, leading dramatical increases in ferrous ion concentration, disrupting cell homeostasis and impairing growth and yield. However, the underlying molecular mechanisms of Fe toxicity response and tolerance in plants are not well characterized yet. Microarray and genome-wide association analyses have shown that rice employs four defense systems to regulate Fe homeostasis under Fe excess. In defense 1, Fe excess tolerance is implemented by Fe exclusion as a result of suppression of genes involved in Fe uptake and translocation such as OsIRT1, OsYSL2, OsTOM1, OsYSL15, OsNRAMP1, OsNAS1, OsNAS2, OsNAAT1, OsDMAS1, and OsIRO2. The Fe-binding ubiquitin ligase, HRZ, is a key regulator that represses Fe uptake genes in response to Fe excess in rice. In defense 2, rice retains Fe in the root system rather than transporting it to shoots. In defense 3, rice compartmentalizes Fe in the shoot. In defense 2 and 3, the vacuolar Fe transporter OsVIT2, Fe storage protein ferritin, and the nicotinamine synthase OsNAS3 mediate the isolation or detoxification of excess Fe. In defense 4, rice detoxifies the ROS produced within the plant body in response to excess Fe. Some OsWRKY transcription factors, S-nitrosoglutathione-reductase variants, p450-family proteins, and OsNAC4, 5, and 6 are implicated in defense 4. These knowledge will facilitate the breeding of tolerant crops with increased productivity in low-pH, Fe-excess soils.

scholarly journals Genotypic Difference in the Responses to Nitrogen Fertilizer Form in Tibetan Wild and Cultivated Barley

Plants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 595
Author(s):  
Shama Naz ◽  
Qiufang Shen ◽  
Jonas Lwalaba Wa Lwalaba ◽  
Guoping Zhang
Keyword(s):  
Wild Barley ◽  
Growth Parameters ◽  
Inorganic Nitrogen ◽  
N Uptake ◽  
Total Soluble Protein ◽  
Organic N ◽  
Genotypic Difference ◽  
N Availability ◽  
Tibetan Wild Barley ◽  
Cultivated Barley

Nitrogen (N) availability and form have a dramatic effect on N uptake and assimilation in plants, affecting growth and development. In the previous studies, we found great differences in low-N tolerance between Tibetan wild barley accessions and cultivated barley varieties. We hypothesized that there are different responses to N forms between the two kinds of barleys. Accordingly, this study was carried out to determine the response of four barley genotypes (two wild, XZ16 and XZ179; and two cultivated, ZD9 andHua30) under 4Nforms (NO3−, NH4+, urea and glycine). The results showed significant reduction in growth parameters such as root/shoot length and biomass, as well as photosynthesis parameters and total soluble protein content under glycine treatment relative to other N treatments, for both wild and cultivated barley, however, XZ179 was least affected. Similarly, ammonium adversely affected growth parameters in both wild and cultivated barleys, with XZ179 being severely affected. On the other hand, both wild and cultivated genotypes showed higher biomass, net photosynthetic rate, chlorophyll and protein in NO3− treatment relative to other three N treatments. It may be concluded that barley undisputedly grows well under inorganic nitrogen (NO3−), however in response to the organic N wild barley prefer glycine more than cultivated barely.

scholarly journals Mechanistic understanding of iron toxicity tolerance in contrasting rice varieties from Africa: 2. Root oxidation ability and oxidative stress control

2020 ◽  
Vol 47 (2) ◽  
pp. 145
Author(s):  
Dorothy A. Onyango ◽  
Fredrickson Entila ◽  
James Egdane ◽  
Myrish Pacleb ◽  
Meggy Lou Katimbang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Sub Saharan Africa ◽  
Rice Varieties ◽  
Excess Iron ◽  
Improvement Programs ◽  
Sub Saharan ◽  
Breeding Efficiency ◽  
Biochemical Analyses ◽  
Fe Toxicity ◽  
And Control

To enhance breeding efficiency for iron (Fe) toxicity tolerance and boost lowland rice production in sub-Saharan Africa, we have characterised the morphological, physiological and biochemical responses of contrasting rice varieties to excess iron. Here, we report the capacity of four varieties (CK801 and Suakoko8 (tolerant), Supa and IR64 (sensitive)) to oxidise iron in the rhizosphere and control iron-induced oxidative stress. The experiments were conducted in hydroponic conditions using modified Magnavaca nutrient solution and 300 ppm of ferrous iron (Fe2+) supplied in the form of FeSO4. Severe oxidative stress was observed in sensitive varieties as revealed by their high levels of lipid peroxidation. Histochemical and biochemical analyses showed that tolerant varieties exhibited a better development of the aerenchyma and greater oxygen release than the sensitive varieties in response to excess Fe. Both suberin and lignin deposits were observed in the root, stem and leaf tissues but with varying intensities depending on the variety. Under iron toxic conditions, tolerant varieties displayed increased superoxide dismutase (SOD), glutathione reductase (GR), peroxidase (POX) and ascorbate peroxidase (APX) activities in both the roots and shoots, whereas sensitive varieties showed increased APX and catalase (CAT) activities in the roots. This study had revealed also that Suakoko8 mainly uses root oxidation to exclude Fe2+ from its rhizosphere, and CK801 possesses a strong reactive oxygen species scavenging system, in addition to root oxidation ability. Key traits associated with these tolerance mechanisms such as a well-developed aerenchyma, radial oxygen loss restricted to the root cap as well as strong activation of antioxidative enzymes (SOD, GR, POX and APX) could be useful selection criteria in rice varietal improvement programs for enhanced Fe toxicity tolerance.

scholarly journals THE EFFECT OF PURIFIED AMOUNT OF TRITERPENE GLYCOSIDES AND THEIR ENRICHED EXTRACT FROM LEAVES OF SILPHIUM PERFOLIATUM L. ON THE GROWTH AND ACTIVITY OF NITRATE REDUCTASE OF WIN-TER WHEAT PLANTS

2019 ◽  
pp. 441-448 ◽  
Author(s):  
Eleonora Sergeyevna Davidyants
Keyword(s):  
Nitrate Reductase ◽  
Winter Wheat ◽  
Seed Treatment ◽  
Nitrate Reductase Activity ◽  
Growth Parameters ◽  
Reductase Activity ◽  
Dry Weight ◽  
Potassium Nitrate ◽  
Triterpene Glycosides ◽  
Nr Activity

The effect of seed treatment with solutions of a purified amount of triterpene glycosides (PATG) containing, as major components, oleanolic acid glycosides – sylphiosides B, C, E, G, and extract (E) enriched with sylphiosides, from Silphium perfoliatum L. (Asteraceae) leaves on growth parameters and nitrate reductase activity (NR, EC 1.6.6.1) of 7-day winter wheat plants (Tritium aestivum L.) was studied. It was shown that, seed treatment with PATG solutions in concentrations of 0.0005 and 0.001% and E in concentrations of 0.2 and 0.4% caused an increase in the length of roots, shoots, wet and dry weight of seedlings compared to the control. The stimulating effect of these concentrations of PATG and E on the total nitrate reductase activity of the roots and leaves of seedlings has been established, and an increase in the stimulating effect of preparations on the activity NR оf against the background of substrate activation of the enzyme potassium nitrate (KNO3) was observed. The greatest increase in the total NR activity of roots and leaves of winter wheat plants was observed when PATG acted at a concentration of 0.001% and E – at a concentration of 0.4%, which amounted respectively 122 and 116%, when adding 1 ml of 50 mM KNO3 solution into the growing medium of plants – 141 and 137% relative to the control. The stimulating effect of exogenous triterpene glycosides on NR activity has been established for the first time. The obtained data allow to theoretically substantiate the possibility of practical use of triterpene glycosides and preparations based on them for the regulation of growth and nitrogen metabolism of plants.

scholarly journals Role of ferritin in the rice tolerance to iron overload

2009 ◽  
Vol 66 (4) ◽  
pp. 549-555 ◽  
Author(s):  
Vivian Chagas da Silveira ◽  
Cristina Fadanelli ◽  
Raul Antonio Sperotto ◽  
Ricardo José Stein ◽  
Luiz Augusto Basso ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Iron Overload ◽  
Iron Homeostasis ◽  
Oryza Sativa L ◽  
Protein Accumulation ◽  
Tolerance Mechanisms ◽  
Protein Levels ◽  
Fe Toxicity ◽  
Excess Fe

Plants ordinarily face iron (Fe) deficiency, since this mineral is poorly available in soils under aerobic conditions. Nonetheless, wetland and irrigated rice plants can be exposed to excess, highly toxic Fe. Ferritin is a ubiquitous Fe-storage protein, important for iron homeostasis. Increased ferritin accumulation resulting from higher Fe availability was shown in some plant species. However, the role of ferritin in tolerance mechanisms to Fe overload in rice is yet to be established. In this study, recombinant rice ferritin was expressed in Escherichia coli, producing an anti-rice ferritin polyclonal antibody which was used to evaluate ferritin accumulation in two rice (Oryza sativa L.) cultivars, either susceptible (BR-IRGA 409) or tolerant (EPAGRI 108) to Fe toxicity. Increased ferritin mRNA and protein levels resulting from excess Fe treatment were detected in both cultivars, with higher ferritin protein accumulation in EPAGRI 108 plants, which also reached lower shoot Fe concentrations when submitted to iron overload. The tolerance mechanism to excess Fe in EPAGRI 108 seems to include both restricted Fe translocation and increased ferritin accumulation. This is the first work that shows higher accumulation of the ferritin protein in an iron-excess tolerant Oryza sativa cultivar, providing evidence of a possible role of this protein in iron tolerance mechanisms.

Ecophysiological responses of Araucaria angustifolia seedlings to different irradiance levels.

2000 ◽  
Vol 48 (4) ◽  
pp. 531 ◽  
Author(s):  
Leandro da S. Duarte ◽  
Lúcia R. Dillenburg
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Growth Parameters ◽  
Reductase Activity ◽  
Chlorophyll Concentration ◽  
Shoot Biomass ◽  
Araucaria Angustifolia ◽  
Low Light ◽  
Pine Seedlings ◽  
Ecophysiological Responses

Brazilian pine (Araucaria angustifolia [Bert.] O.Ktze.) is an indigenous conifer of the southern region of South America, typically regarded as a sun-loving species. However, there is insufficient information on the species’ behaviour under different irradiances to characterise its plasticity to light. The purpose of this work was to measure some ecophysiological responses of Brazilian pine seedlings to three irradiance levels: 100, 45 and 10% full sunlight. Thirty seedlings were grown under each of the irradiance treatments and, after 5 months, growth parameters, leaf chlorophyll concentration and in vivo nitrate reductase activity, in both leaves and roots, were analysed. There was no increase in shoot biomass allocation in response to shading, in contrast to results from other experiments. Only low-light seedlings showed significant increase in specific leaf area, as well as in the ratio of height to shoot biomass. Chlorophyll content and the ratio of chlorophyll a to chlorophyll b did not vary among treatments. Nitrate reductase activity was detected only in roots and was reduced in the low-light treatment. An overall analysis of the results points to a normal growth of Brazilian pine seedlings at both high- and medium-light sites, at least in their initial stages of development.

scholarly journals Comparative Transcriptomics of Lowland Rice Varieties Uncovers Novel Candidate Genes for Adaptive Iron Excess Tolerance

2021 ◽  
Author(s):  
Saradia Kar ◽  
Hans-Jörg Mai ◽  
Hadeel Khalouf ◽  
Heithem Ben Abdallah ◽  
Samantha Flachbart ◽  
...  
Keyword(s):  
Leaf Growth ◽  
Expression Patterns ◽  
Reactive Oxygen Species Generation ◽  
Metal Homeostasis ◽  
Lowland Rice ◽  
Rice Varieties ◽  
Ontology Term ◽  
Fe Toxicity ◽  
Fe Excess ◽  
Excess Fe

Abstract Iron (Fe) toxicity is a major challenge for plant cultivation in acidic waterlogged soil environments, where lowland rice is a major staple food crop. Only few studies have addressed the molecular characterization of excess Fe tolerance in rice, and these highlight different mechanisms for Fe tolerance. Out of 16 lowland rice varieties, we identified a pair of contrasting lines, Fe-tolerant Lachit and -susceptible Hacha. The two lines differed in their physiological and morphological responses to excess Fe, including leaf growth, leaf rolling, reactive oxygen species generation and Fe and metal contents. These responses were likely due to genetic origin as they were mirrored by differential gene expression patterns, obtained through RNA sequencing, and corresponding gene ontology term enrichment in tolerant vs. susceptible lines. Thirty-five genes of the metal homeostasis category, mainly root expressed, showed differential transcriptomic profiles suggestive of an induced tolerance mechanism. Twenty-two out of these 35 metal homeostasis genes were present in selection sweep genomic regions, in breeding signatures, and/or differentiated during rice domestication. These findings suggest that Fe excess tolerance is an important trait in the domestication of lowland rice, and the identified genes may further serve to design the targeted Fe tolerance breeding of rice crops.

scholarly journals Population genetic structure and association mapping for iron toxicity tolerance in rice

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0246232
Author(s):  
S. Pawar ◽  
E. Pandit ◽  
I. C. Mohanty ◽  
D. Saha ◽  
S. K. Pradhan
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Association Mapping ◽  
Stress Tolerance ◽  
Linear Model ◽  
Generalized Linear Model ◽  
Mixed Linear Model ◽  
Iron Toxicity ◽  
Rice Grain ◽  
Fe Toxicity

Iron (Fe) toxicity is a major abiotic stress which severely reduces rice yield in many countries of the world. Genetic variation for this stress tolerance exists in rice germplasms. Mapping of gene(s)/QTL controlling the stress tolerance and transfer of the traits into high yielding rice varieties are essential for improvement against the stress. A panel population of 119 genotypes from 352 germplasm lines was constituted for detecting the candidate gene(s)/QTL through association mapping. STRUCTURE, GenAlEx and Darwin softwares were used to classify the population. The marker-trait association was detected by considering both the Generalized Linear Model (GLM) and Mixed Linear Model (MLM) analyses. Wide genetic variation was observed among the genotypes present in the panel population for the stress tolerance. Linkage disequilibrium was detected in the population for iron toxicity tolerance. The population was categorized into three genetic structure groups. Marker-trait association study considering both the Generalized Linear Model (GLM) and Mixed Linear Model (MLM) showed significant association of leaf browning index (LBI) with markers RM471, RM3, RM590 and RM243. Three novel QTL controlling Fe-toxicity tolerance were detected and designated as qFeTox4.3, qFeTox6.1 and qFeTox10.1. A QTL reported earlier in the marker interval of C955-C885 on chromosome 1 is validated using this panel population. The present study showed that QTL controlling Fe-toxicity tolerance to be co-localized with the QTL for Fe-biofortification of rice grain indicating involvement of common pathway for Fe toxicity tolerance and Fe content in rice grain. Fe-toxicity tolerance QTL qFeTox6.1 was co-localized with grain Fe-biofortification QTLs qFe6.1 and qFe6.2 on chromosome 6, whereas qFeTox10.1 was co-localized with qFe10.1 on chromosome 10. The Fe-toxicity tolerance QTL detected from this mapping study will be useful in marker-assisted breeding programs.

Effect of salt stress on antioxidant defence system in soybean root nodules

1998 ◽  
Vol 25 (6) ◽  
pp. 665 ◽  
Author(s):  
María E. Comba ◽  
María P. Benavides ◽  
María L. Tomaro
Keyword(s):  
Superoxide Dismutase ◽  
Antioxidant Enzymes ◽  
Glutathione Reductase ◽  
Ascorbate Peroxidase ◽  
Reduced Glutathione ◽  
Nitrogenase Activity ◽  
Reductase Activity ◽  
Saline Stress ◽  
Antioxidant Defence ◽  
Antioxidant Defence System

The antioxidant defence systems of soybean (Glycine max (L.) Merr) nodules responded differently to 50 and 200 mM NaCl. At 50 mM NaCl, leghaemoglobin content and nitrogenase activity remained unaltered but there was an overall increase in the antioxidant enzymes (ascorbate peroxidase, catalase, glutathione reductase and superoxide dismutase) and in reduced glutathione. After returning the salinised nodules to a non-saline environment (recovery), the enzymatic activities returned to the initial values but reduced glutathione remained high with respect to the controls measured at the end of the experiment (final controls). Severe salt treatment reduced the leghaemoglobin content and nitrogenase activity by 31% and 50%, respectively. Ascorbate peroxidase, catalase and glutathione reductase activities decreased between 30 and 100% while superoxide dismutase and reduced glutathione increased over the controls by 19% and 30% respectively. After recovery, glutathione reductase increased over the final controls and reduced glutathione remained as under 50 mM NaCl. Malondialdehyde content and total protein remained unchanged in nodules treated with the two salt concentrations. These results suggest that under mild saline stress, the elevated levels of the antioxidant enzymes and reduced glutathione protect nodules against the activated oxygen species thus avoiding lipid and protein peroxidation, and leghaemoglobin breakdown. However, severe saline treatment produced an irreversible decay in the leghaemoglobin content and nitrogenase activity despite the high reduced glutathione level and glutathione reductase activity.

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