scholarly journals Supraoptimal Iron Nutrition of Brassica napus Plants Suppresses the Iron Uptake of Chloroplasts by Down-Regulating Chloroplast Ferric Chelate Reductase

2021 ◽  
Vol 12 ◽  
Author(s):  
Máté Sági-Kazár ◽  
Helga Zelenyánszki ◽  
Brigitta Müller ◽  
Barnabás Cseh ◽  
Balázs Gyuris ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Photosynthetic Apparatus ◽  
Iron Nutrition ◽  
Fe Deficiency ◽  
Chloroplast Envelope ◽  
Substrate Affinity ◽  
Mesophyll Cells ◽  
Ferric Chelate Reductase ◽  
Fe Uptake ◽  
Fe Nutrition

Iron (Fe) is an essential micronutrient for plants. Due to the requirement for Fe of the photosynthetic apparatus, the majority of shoot Fe content is localised in the chloroplasts of mesophyll cells. The reduction-based mechanism has prime importance in the Fe uptake of chloroplasts operated by Ferric Reductase Oxidase 7 (FRO7) in the inner chloroplast envelope membrane. Orthologue of Arabidopsis thaliana FRO7 was identified in the Brassica napus genome. GFP-tagged construct of BnFRO7 showed integration to the chloroplast. The time-scale expression pattern of BnFRO7 was studied under three different conditions: deficient, optimal, and supraoptimal Fe nutrition in both leaves developed before and during the treatments. Although Fe deficiency has not increased BnFRO7 expression, the slight overload in the Fe nutrition of the plants induced significant alterations in both the pattern and extent of its expression leading to the transcript level suppression. The Fe uptake of isolated chloroplasts decreased under both Fe deficiency and supraoptimal Fe nutrition. Since the enzymatic characteristics of the ferric chelate reductase (FCR) activity of purified chloroplast inner envelope membranes showed a significant loss for the substrate affinity with an unchanged saturation rate, protein level regulation mechanisms are suggested to be also involved in the suppression of the reduction-based Fe uptake of chloroplasts together with the saturation of the requirement for Fe.

Nitrate metabolism in relation to the aspartate-type C-4 pathway of photosynthesis in Eleusine coracana

1974 ◽  
Vol 52 (12) ◽  
pp. 2599-2605 ◽  
Author(s):  
C. K. M. Rathnam ◽  
V. S. R. Das
Keyword(s):  
Glutamate Dehydrogenase ◽  
Eleusine Coracana ◽  
Bundle Sheath ◽  
Chloroplast Envelope ◽  
Mesophyll Cells ◽  
Bundle Sheath Cells ◽  
Nitrate Metabolism ◽  
Type C ◽  
Envelope Membranes ◽  
Sheath Cells

The intercellular and intracellular distributions of nitrate assimilating enzymes were studied. Nitrate reductase was found to be localized on the chloroplast envelope membranes. The chloroplastic NADPH – glutamate dehydrogenase was concentrated in the mesophyll cells. The extrachloroplastic NADH – glutamate dehydrogenase was localized in the bundle sheath cells. Glutamate synthesized in the mesophyll chloroplasts was interpreted to be utilized exclusively in the synthesis of aspartate, while in the bundle sheath cells it was thought to be consumed in other cellular metabolic processes. Based on the results, a scheme is proposed to account for the nitrate metabolism in the leaves of Eleusine coracana Gaertn. in relation to its aspartate-type C-4 pathway of photosynthesis.

scholarly journals Iron nutrition in the UK: getting the balance right

2004 ◽  
Vol 63 (4) ◽  
pp. 519-528 ◽  
Author(s):  
Susan J. Fairweather-Tait
Keyword(s):  
Negative Impact ◽  
Iron Nutrition ◽  
Fe Deficiency ◽  
Adaptive Responses ◽  
Childbearing Age ◽  
Related Factors ◽  
High Fibre ◽  
Single Meal ◽  
Fe Homeostasis ◽  
The Uk

Fe homeostasis is considered in the context of the UK diet, using information on Fe intake and status from the National Diet and Nutrition Surveys. The importance of assessing Fe availability rather than total Fe intake is discussed. Dietary and host-related factors that determine Fe bioavailability (Fe utilised for Hb production) are reviewed using information from single-meal studies. When adaptive responses are taken into consideration, foods associated with higher Fe status include meat (haem-Fe and the ‘meat factor’) and fruits and fruit juice (vitamin C). Foods that may have a negative impact include dairy products (Ca), high-fibre foods (phytate) and tea and coffee (polyphenols), but the effects are more apparent in groups with marginal Fe deficiency, such as women of childbearing age. Analysis of dietary intake data on a meal-by-meal basis is needed to predict the influence of changing dietary patterns on Fe nutrition in the UK. Current information suggests that in the UK Fe deficiency is a greater problem than Fe overload.

scholarly journals Iron absorption in hepcidin1 knockout mice

2011 ◽  
Vol 105 (11) ◽  
pp. 1583-1591 ◽  
Author(s):  
Patarabutr Masaratana ◽  
Abas H. Laftah ◽  
Gladys O. Latunde-Dada ◽  
Sophie Vaulont ◽  
Robert J. Simpson ◽  
...  
Keyword(s):  
Knockout Mice ◽  
Iron Absorption ◽  
Fe Deficiency ◽  
Acute Effects ◽  
Regulatory Peptide ◽  
Fe Uptake

Hepcidin, the Fe-regulatory peptide, has been shown to inhibit Fe absorption and reticuloendothelial Fe recycling. The present study was conducted to explore the mechanism of in vivo Fe regulation through genetic disruption of hepcidin1 and acute effects of hepcidin treatment in hepcidin1 knockout (Hepc1− / − ) and heterozygous mice. Hepcidin1 disruption resulted in significantly increased intestinal Fe uptake. Hepcidin injection inhibited Fe absorption in both genotypes, but the effects were more evident in the knockout mice. Hepcidin administration was also associated with decreased membrane localisation of ferroportin in the duodenum, liver and, most significantly, in the spleen of Hepc1− / −  mice. Hypoferraemia was induced in heterozygous mice by hepcidin treatment, but not in Hepc1− / −  mice, 4 h after injection. Interestingly, Fe absorption and serum Fe levels in Hepc1− / −  and heterozygous mice fed a low-Fe diet were not affected by hepcidin injection. The present study demonstrates that hepcidin deficiency causes increased Fe absorption. The effects of hepcidin were abolished by dietary Fe deficiency, indicating that the response to hepcidin may be influenced by dietary Fe level or Fe status.

scholarly journals MNB1 gene is involved in regulating the iron-deficiency stress response in Arabidopsis thaliana

2021 ◽  
Author(s):  
Hui Song ◽  
Feng Chen ◽  
Xi Wu ◽  
Min Hu ◽  
Qingliu Geng ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Arabidopsis Thaliana ◽  
Normal Growth ◽  
Developmental Changes ◽  
Fe Deficiency ◽  
Oxygen Species ◽  
Mineral Element ◽  
Wild Type ◽  
Transcription Level ◽  
Fe Uptake

Abstract Abstract Iron (Fe) is an indispensable mineral element for normal growth of plants. Fe deficiency induces a complex series of responses in plants, involving physiological and developmental changes, to increase Fe uptake from soil. However, the molecular mechanism involved in plant Fe-deficiency is not well understood. Here, we found that the MNB1 gene is involved in modulating Fe-deficiency response in Arabidopsis thaliana . The expression of MNB1 was inhabited by Fe-deficiency stress. Knockout of MNB1 led to enhanced Fe accumulation and tolerance, whereas the MNB1-overexpressing plants were sensitive to Fe-deficiency stress. Lower H 2 O 2 concentrations in mnb1 mutant plants were examined under Fe deficiency circumstances compared to wild-type. On the contray, higher H 2 O 2 concentrations were found in MNB1-overexpressing plants, which was adversely linked with malondialdehyde (MDA) concentrations. Furthermore, in mnb1 mutants, the transcription level of the Fe-uptake and translocation genes, FIT , IRT1 , FRO2 , Z IF , FRD3 , NAS4 , PYE and MYB72 , were considerably elevated during Fe-deficiency stress, resulting in higher Fe accumulation. Together, our findings show that the MNB1 gene negatively controls the Fe-deficiency response in Arabidopsis via modulating reactive oxygen species (ROS) levels and the ROS-mediated signaling pathway, thereby affecting the expression of Fe-uptake and translocation genes.

scholarly journals FIT, a regulatory hub for iron deficiency and stress signaling in roots, and FIT-dependent and -independent gene signatures

2020 ◽  
Vol 71 (5) ◽  
pp. 1694-1705 ◽  
Author(s):  
Birte Schwarz ◽  
Petra Bauer
Keyword(s):  
Transcription Factor ◽  
Protein Interactions ◽  
Fe Deficiency ◽  
Bhlh Transcription Factor ◽  
Root Cells ◽  
Gene Signatures ◽  
Helix Loop Helix ◽  
Independent Gene ◽  
Fe Uptake ◽  
Fe Acquisition

Abstract Iron (Fe) is vital for plant growth. Plants balance the beneficial and toxic effects of this micronutrient, and tightly control Fe uptake and allocation. Here, we review the role of the basic helix–loop–helix (bHLH) transcription factor FIT (FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR) in Fe acquisition. FIT is not only essential, it is also a central regulatory hub in root cells to steer and adjust the rate of Fe uptake by the root in a changing environment. FIT regulates a subset of root Fe deficiency (–Fe) response genes. Based on a combination of co-expression network and FIT-dependent transcriptome analyses, we defined a set of FIT-dependent and FIT-independent gene expression signatures and co-expression clusters that encode specific functions in Fe regulation and Fe homeostasis. These gene signatures serve as markers to integrate novel regulatory factors and signals into the –Fe response cascade. FIT forms a complex with bHLH subgroup Ib transcription factors. Furthermore, it interacts with key regulators from different signaling pathways that either activate or inhibit FIT function to adjust Fe acquisition to growth and environmental constraints. Co-expression clusters and FIT protein interactions suggest a connection of –Fe with ABA responses and root cell elongation processes that can be explored in future studies.

Transcriptional and physiological changes in relation to Fe uptake under conditions of Fe-deficiency and Cd-toxicity in roots of Vigna radiata L.

2014 ◽  
Vol 127 (6) ◽  
pp. 731-742 ◽  
Author(s):  
Sowbiya Muneer ◽  
Byoung Ryong Jeong ◽  
Tae-Hwan Kim ◽  
Jeong Hyun Lee ◽  
Prabhakaran Soundararajan
Keyword(s):  
Vigna Radiata ◽  
Fe Deficiency ◽  
Physiological Changes ◽  
Cd Toxicity ◽  
Fe Uptake

Effects of different foliar iron applications on activity of ferric chelate reductase and concentration of iron in sweet potato (Ipomoea batatas)

2019 ◽  
Vol 70 (4) ◽  
pp. 359
Author(s):  
Xiaoli Tan ◽  
Xin Yang ◽  
Yinan Xie ◽  
Han Xiao ◽  
Mengjiao Liu ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Ipomoea Batatas ◽  
Block Design ◽  
Fe Deficiency ◽  
Relative Efficacy ◽  
Ferric Chelate Reductase ◽  
Deficiency Symptoms ◽  
Leaf Chlorosis ◽  
And Control ◽  
Effective Compound

We studied the relative efficacy of different forms of foliar iron (Fe) fertilisation on leaf re-greening in Fe-deficient, purple-fleshed sweet potato (Ipomoea batatas (L.) Lam.) varieties xuzi8 and xuzi6. Activities of ferric chelate reductase (FCR) and concentrations of Fe were measured in the leaves and roots at intervals over 5 days to quantify recovery from leaf chlorosis. Freshly expanded and chlorotic leaves were immersed in one of three different fertiliser compounds containing 9 mm Fe: FeSO4, Fe2(SO4)3, Fe(III)-EDTA. An Fe-sufficient treatment and an Fe-deficient control were included. The experiment had a completely randomised block design with five replications per treatment and was conducted in a sunlit glasshouse. For variety xuzi8, leaf FCR activity in the Fe2(SO4)3 treatment was highest at 1 h after application, and higher than all other treatments, whereas FeSO4 and Fe(III)-EDTA treatments showed their highest FCR at day 5 after application, both significantly higher than the Fe2(SO4)3 and control treatments. Furthermore, leaf Fe concentration reached a maximum in the FeSO4 treatment at day 1, and in the Fe2(SO4)3 treatment at day 3. By contrast, root Fe concentration was relatively constant and lower in the foliar Fe treatments than the Fe-sufficient and -deficient treatments. For variety xuzi6, leaf SPAD was higher with the Fe2(SO4)3 than the FeSO4 treatment at day 5 after application. In general, FCR activity and Fe concentrations in roots and leaves of xuzi6 were higher than those of xuzi8. Variations in leaf Fe concentrations were similar for both the FeSO4 and Fe2(SO4)3 treatments of the two varieties. Maximum leaf Fe levels in xuzi6 were ~4-fold those in xuzi8. The results of the study suggest that foliar-applied Fe2(SO4)3 was the most effective compound at correcting Fe-deficiency symptoms. The higher leaf and root FCR activity and Fe concentration in xuzi6 might explain its higher tolerance to Fe deficiency and better re-greening than xuzi8.

scholarly journals Studies on the control of iron uptake by rabbit small intestine

1982 ◽  
Vol 47 (2) ◽  
pp. 251-258 ◽  
Author(s):  
T. M. Cox ◽  
M. W. O'Donnell
Keyword(s):  
Regional Distribution ◽  
Maximum Velocity ◽  
Whole Body ◽  
Fe Deficiency ◽  
Distal Intestine ◽  
Body Retention ◽  
Fe Uptake ◽  
Active Transport Process

1. Whole-body retention in vivo and uptake of 59Fe-labelled ascorbate and nitrilotriacetate chelates by intestinal slices in vitro were determined in groups of normal control rabbits and rabbits with experimentally-induced Fe deficiency.2. Over-all absorption as measured by retention of doses of either chelate was greatly increased in conditions of Fe deficiency.3. Intestinal Fe uptake in vitro was inhibited up to 77% in the presence of 2,4-dinitrophenol and sodium fluoride. Initial rates showed saturation within the concentration range 18–450 μmol/l, suggesting that uptake was brought about by an active transport process.4. When studied at chelate concentrations of 450 μmol/l, significant regional differences in uptake rates were observed. Uptake in duodenal slices was increased when compared with slices from jejunum and ileum.5. Fe uptake from ferric and ferrous chelates was greatly enhanced in Fe deficiency. This was chiefly due to increases in uptake by slices from the duodenum, but uptake into slices of distal intestine was also stimulated.6. Kinetic analysis of Fe uptake by duodenal slices from animals rendered Fe deficient by diet or repeated bleeding indicated in both groups an increased apparent maximum velocity (Vmax) for influx of Fe without significant changes in apparent affinity for Fe.7. The experiments provide further insight into the nature and regional distribution of transport of Fe into the intestine and suggest, in the rabbit, that important control of Fe absorption may be exerted by an active process operating at this initial entry step.

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