What are hemoglobins doing in plants?

1998 ◽  
Vol 76 (5) ◽  
pp. 707-712 ◽  
Author(s):  
Robert D Hill
Keyword(s):  
Plant Community ◽  
Plant Cells ◽  
Gold Medal ◽  
Plant Biology ◽  
Flooding Tolerance ◽  
Energy Status ◽  
Low Oxygen ◽  
Oxygen Stress ◽  
Oxygen Dissociation ◽  
Oxygen Tensions

Within the last 3-4 years, evidence has accumulated to indicate that hemoglobin proteins exist widely in the plant community. This review presents some of the evidence to support this view and describes some of the properties of a barley hemoglobin. Barley hemoglobin has a strong avidity for oxygen, having an oxygen dissociation constant for oxyhemoglobin of 3 nmol L-1. It is induced under low oxygen tensions, with the induction regulated by ATP, or some consequence of ATP action. Experiments with transformed maize cells indicate that hemoglobin acts to improve the energy status of plant cells under low oxygen stress. It is postulated that hemoglobin acts as an oxygenase in plants. The review is a consequence of a CSPP Gold Medal Presentation at the Plant Biology 1997 Meeting in Vancouver, B.C.Key words: nonsymbiotic hemoglobins, hypoxia, barley, flooding tolerance.

Pyrophosphate as an alternative energy currency in plants

2021 ◽  
Vol 478 (8) ◽  
pp. 1515-1524
Author(s):  
Abir U. Igamberdiev ◽  
Leszek A. Kleczkowski
Keyword(s):  
Metabolic Pathways ◽  
Energy Efficient ◽  
Alternative Energy ◽  
Plant Cells ◽  
Atp Synthesis ◽  
Continuous Operation ◽  
Low Oxygen ◽  
Pyruvate Phosphate Dikinase ◽  
Oxygen Stress ◽  
Membrane Bound

In the conditions of [Mg2+] elevation that occur, in particular, under low oxygen stress and are the consequence of the decrease in [ATP] and increase in [ADP] and [AMP], pyrophosphate (PPi) can function as an alternative energy currency in plant cells. In addition to its production by various metabolic pathways, PPi can be synthesized in the combined reactions of pyruvate, phosphate dikinase (PPDK) and pyruvate kinase (PK) by so-called PK/PPDK substrate cycle, and in the reverse reaction of membrane-bound H+-pyrophosphatase, which uses the energy of electrochemical gradients generated on tonoplast and plasma membrane. The PPi can then be consumed in its active forms of MgPPi and Mg2PPi by PPi-utilizing enzymes, which require an elevated [Mg2+]. This ensures a continuous operation of glycolysis in the conditions of suppressed ATP synthesis, keeping metabolism energy efficient and less dependent on ATP.

Dynamic changes of antioxidants and fermentative metabolites in apple peel in relation to storage, controlled atmosphere, and initial low oxygen stress

2021 ◽  
Vol 288 ◽  
pp. 110312
Author(s):  
Marina Buccheri ◽  
Valentina Picchi ◽  
Maurizio Grassi ◽  
Davide Gandin ◽  
Giulia Bianchi ◽  
...  
Keyword(s):  
Controlled Atmosphere ◽  
Low Oxygen ◽  
Dynamic Changes ◽  
Oxygen Stress ◽  
Apple Peel

scholarly journals Identification and Functional Analysis of ThADH1 and ThADH4 Genes Involved in Tolerance to Waterlogging Stress in Taxodium hybrid ‘Zhongshanshan 406’

Genes ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 225
Author(s):  
Lei Xuan ◽  
Jianfeng Hua ◽  
Fan Zhang ◽  
Zhiquan Wang ◽  
Xiaoxiao Pei ◽  
...  
Keyword(s):  
Ethanol Metabolism ◽  
Flooding Tolerance ◽  
Transcriptome Data ◽  
Low Oxygen ◽  
Anaerobic Conditions ◽  
Waterlogging Tolerance ◽  
Waterlogging Stress ◽  
Adh Genes ◽  
Oxygen Conditions ◽  
Stems And Leaves

The Taxodium hybrid ‘Zhongshanshan 406’ (T. hybrid ‘Zhongshanshan 406’) [Taxodium mucronatum Tenore × Taxodium distichum (L.). Rich] has an outstanding advantage in flooding tolerance and thus has been widely used in wetland afforestation in China. Alcohol dehydrogenase genes (ADHs) played key roles in ethanol metabolism to maintain energy supply for plants in low-oxygen conditions. Two ADH genes were isolated and characterized—ThADH1 and ThADH4 (GenBank ID: AWL83216 and AWL83217—basing on the transcriptome data of T. hybrid ‘Zhongshanshan 406’ grown under waterlogging stress. Then the functions of these two genes were investigated through transient expression and overexpression. The results showed that the ThADH1 and ThADH4 proteins both fall under ADH III subfamily. ThADH1 was localized in the cytoplasm and nucleus, whereas ThADH4 was only localized in the cytoplasm. The expression of the two genes was stimulated by waterlogging and the expression level in roots was significantly higher than those in stems and leaves. The respective overexpression of ThADH1 and ThADH4 in Populus caused the opposite phenotype, while waterlogging tolerance of the two transgenic Populus significantly improved. Collectively, these results indicated that genes ThADH1 and ThADH4 were involved in the tolerance and adaptation to anaerobic conditions in T. hybrid ‘Zhongshanshan 406’.

Sensitivity of malaria parasites to nitric oxide at low oxygen tensions

The Lancet ◽  
1998 ◽  
Vol 351 (9116) ◽  
pp. 1630 ◽  
Author(s):  
AW Taylor-Robinson ◽  
M Looker
Keyword(s):  
Nitric Oxide ◽  
Low Oxygen ◽  
Malaria Parasites ◽  
Oxygen Tensions

Response of pomegranate arils (cv. Wonderful) to low oxygen stress under active modified atmosphere condition

2018 ◽  
Vol 99 (3) ◽  
pp. 1088-1097 ◽  
Author(s):  
Zinash A Belay ◽  
Oluwafemi J Caleb ◽  
Pramod V Mahajan ◽  
Umezuruike L Opara
Keyword(s):  
Modified Atmosphere ◽  
Low Oxygen ◽  
Oxygen Stress ◽  
Pomegranate Arils

Influence of carbon monoxide on hemoglobin-oxygen binding

1976 ◽  
Vol 41 (6) ◽  
pp. 893-899 ◽  
Author(s):  
M. P. Hlastala ◽  
H. P. McKenna ◽  
R. L. Franada ◽  
J. C. Detter
Keyword(s):  
Carbon Monoxide ◽  
Oxygen Affinity ◽  
Co2 Concentration ◽  
Bohr Effect ◽  
Oxygen Binding ◽  
Dissociation Curve ◽  
Low Oxygen ◽  
Oxygen Dissociation ◽  
Initial Binding ◽  
Fixed Acid

The oxygen dissociation curve and Bohr effect were measured in normal whole blood as a function of carboxyhemoglobin concentration [HbCO]. pH was changed by varying CO2 concentration (CO2 Bohr effect) or by addition of isotonic NaOH or HCl at constant PCO2 (fixed acid Bohr effect). As [HbCO] varied through the range of 2, 25, 50, and 75%, P50 was 26.3, 18.0, 11.6, and 6.5 mmHg, respectively. CO2 Bohr effect was highest at low oxygen saturations. This effect did not change as [HbCO] was increased. However, as [HbCO] was increased from 2 to 75%, the fixed acid Bohr factor increased in magnitude from -0.20 to -0.80 at very low oxygen saturations. The effect of molecular CO2 binding (carbamino) on oxygen affinity was eliminated at high [HbCO]. These results are consistent with the initial binding of O2 or CO to thealpha-chain of hemoglobin. The results also suggest that heme-heme interaction is different for oxygen than for carbon monoxide.

scholarly journals The effect of temperature on the oxygen dissociation curves of whole blood of larval and adult lampreys (Geotria australis)

1982 ◽  
Vol 97 (1) ◽  
pp. 253-261
Author(s):  
D. J. Macey ◽  
I. C. Potter
Keyword(s):  
Whole Blood ◽  
Life Cycle Stage ◽  
Effect Of Temperature ◽  
High Affinity ◽  
Oxygen Dissociation ◽  
Geotria Australis ◽  
Oxygen Tensions ◽  
Dissociation Curves ◽  
Hill Plots ◽  
Very High

1. Oxygen dissociation curves of the whole blood of larvae and adults of the Southern Hemisphere lamprey Geotria australis have been determined between pH 6.8 and 8.2 at 5, 15 and 25 degrees C. 2. The P50's at temperatures of 5, 15 and 25 degrees C and a pH of 7.75 were respectively 0.57, 0.92 and 1.19 mmHg in larvae and 6.9, 10.3 and 19.0 mmHg in adults. 3. The relatively very high affinity of larval blood for oxygen may reflect an adaptation to low environmental oxygen tensions. 4. The Bohr shift was not significantly affected by either temperature or life-cycle stage. 5. The slope (n) in Hill plots increased with temperature and oxygen saturation, and was greater in adults than in larvae.

scholarly journals Cytokinins Stimulate Plasmodesmatal Transport in Leaves

2021 ◽  
Vol 12 ◽  
Author(s):  
Wilson Horner ◽  
Jacob O. Brunkard
Keyword(s):  
Cell Walls ◽  
Fluorescent Protein ◽  
Plant Cells ◽  
Plant Biology ◽  
Negative Regulator ◽  
Cytokinin Signaling ◽  
Dynamic Changes ◽  
Cytokinin Receptors ◽  
Green Fluorescent ◽  
Development Regulation

Plant cells are connected by plasmodesmata (PD), nanoscopic channels in cell walls that allow diverse cytosolic molecules to move between neighboring cells. PD transport is tightly coordinated with physiology and development, although the range of signaling pathways that influence PD transport has not been comprehensively defined. Several plant hormones, including salicylic acid (SA) and auxin, are known to regulate PD transport, but the effects of other hormones have not been established. In this study, we provide evidence that cytokinins promote PD transport in leaves. Using a green fluorescent protein (GFP) movement assay in the epidermis of Nicotiana benthamiana, we have shown that PD transport significantly increases when leaves are supplied with exogenous cytokinins at physiologically relevant concentrations or when a positive regulator of cytokinin responses, ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 5 (AHP5), is overexpressed. We then demonstrated that silencing cytokinin receptors, ARABIDOPSIS HISTIDINE KINASE 3 (AHK3) or AHK4 or overexpressing a negative regulator of cytokinin signaling, AAHP6, significantly decreases PD transport. These results are supported by transcriptomic analysis of mutants with increased PD transport (ise1–4), which show signs of enhanced cytokinin signaling. We concluded that cytokinins contribute to dynamic changes in PD transport in plants, which will have implications in several aspects of plant biology, including meristem patterning and development, regulation of the sink-to-source transition, and phytohormone crosstalk.

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