scholarly journals ‘Green’ …yet wasting energy?: Mitochondrial respiration in plants

2006 ◽  
Vol 28 (4) ◽  
pp. 13-16
Author(s):  
Anthony L. Moore ◽  
Mary S. Albury ◽  
Paul G. Crichton
Keyword(s):  
Plant Growth ◽  
Mitochondrial Respiration ◽  
Alternative Oxidase ◽  
Plant Mitochondria ◽  
Carboxylate Group ◽  
Defence Mechanism ◽  
Alternative Pathways ◽  
Warm Environment ◽  
Inner Surface ◽  
Iron Carboxylate

Plant mitochondria are characterized by the presence of both phosphorylating (cytochrome) and non-phosphorylating (alternative) pathways, the activity of which directly affects the efficiency of mitochondrial energy conservation. The cyanide-insensitive AOX (alternative oxidase) is located on the inner surface of the inner membrane, results in the oxidation of ubiquinol and the net reduction of oxygen to water, is non-protonmotive and is considered to be one of the newest members of the di-iron carboxylate group of proteins. In thermogenic tissues it plays a key role in pollination and the maintenance of a warm environment for the flower, whereas in non-thermogenic tissues functions include acting as an energy overflow, part of the oxygen defence mechanism and maintaining plant growth homoeostasis.

The uncoupling of respiration in plant mitochondria: keeping reactive oxygen and nitrogen species under control

2020 ◽  
Author(s):  
Vasily N Popov ◽  
Mikhail Y Syromyatnikov ◽  
Alisdair R Fernie ◽  
Subhra Chakraborty ◽  
Kapuganti Jagadis Gupta ◽  
...  
Keyword(s):  
Mitochondrial Respiration ◽  
Uncoupling Protein ◽  
Plant Mitochondria ◽  
Reactive Oxygen ◽  
Stress Factors ◽  
Atp Production ◽  
Alternative Pathways ◽  
Mitochondrial Functions ◽  
Far From Equilibrium

Abstract Plant mitochondrial respiration involves the operation of various alternative pathways. These pathways participate, both directly and indirectly, in the maintenance of mitochondrial functions though they do not contribute to energy production, being uncoupled from the generation of an electrochemical gradient across the mitochondrial membrane and thus from ATP production. Recent findings suggest that uncoupled respiration is involved in reactive oxygen species (ROS) and nitric oxide (NO) scavenging, regulation, and homeostasis. Here we discuss specific roles and possible functions of uncoupled mitochondrial respiration in ROS and NO metabolism. The mechanisms of expression and regulation of the NDA-, NDB- and NDC-type non-coupled NADH and NADPH dehydrogenases, the alternative oxidase (AOX), and the uncoupling protein (UCP) are examined in relation to their involvement in the establishment of the stable far-from-equilibrium state of plant metabolism. The role of uncoupled respiration in controlling the levels of ROS and NO as well as inducing signaling events is considered. Secondary functions of uncoupled respiration include its role in protection from stress factors and roles in biosynthesis and catabolism. It is concluded that uncoupled mitochondrial respiration plays an important role in providing rapid adaptation of plants to changing environmental factors via regulation of ROS and NO.

scholarly journals Functions of PPR Proteins in Plant Growth and Development

2021 ◽  
Vol 22 (20) ◽  
pp. 11274
Author(s):  
Xiulan Li ◽  
Mengdi Sun ◽  
Shijuan Liu ◽  
Qian Teng ◽  
Shihui Li ◽  
...  
Keyword(s):  
Plant Growth ◽  
Stress Responses ◽  
Rna Processing ◽  
Growth And Development ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Plant Mitochondria ◽  
Research Progress ◽  
Plant Growth And Development ◽  
Ppr Proteins

Pentatricopeptide repeat (PPR) proteins form a large protein family in land plants, with hundreds of different members in angiosperms. In the last decade, a number of studies have shown that PPR proteins are sequence-specific RNA-binding proteins involved in multiple aspects of plant organellar RNA processing, and perform numerous functions in plants throughout their life cycle. Recently, computational and structural studies have provided new insights into the working mechanisms of PPR proteins in RNA recognition and cytidine deamination. In this review, we summarized the research progress on the functions of PPR proteins in plant growth and development, with a particular focus on their effects on cytoplasmic male sterility, stress responses, and seed development. We also documented the molecular mechanisms of PPR proteins in mediating RNA processing in plant mitochondria and chloroplasts.

scholarly journals Characterization of Suspension Cultures of Arabidopsis thaliana (L.) Heynh Cells with Altered Expression of the Gene of Alternative Mitochondrial Oxidase Aox1a and Analysis of their Frost Resistance

2021 ◽  
Vol 35 ◽  
pp. 3-18
Author(s):  
A. V. Stepanov ◽  
◽  
S. A. Kashin ◽  
N. S. Zabanova ◽  
O. A. Fedotova ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Suspension Culture ◽  
Mitochondrial Respiration ◽  
Frost Resistance ◽  
Alternative Oxidase ◽  
Uncoupling Protein ◽  
Living Cells ◽  
Subzero Temperature ◽  
Wild Type ◽  
Culture Cells

The enzyme alternative cyanide-resistant oxidase (AOX) localized in mitochondria is involved in the processes of plant adaptation to various unfavorable biotic and abiotic factors. Transfer of electrons from ubiquinone to oxygen by alternative oxidase has a nonprotonmotive character and, by bypassing two sites of H+ pumping in complexes III and IV, lowers the energy efficiency of respiration and energy of electron flow through AOX is released as heat. In this work, we characterized heterotrophic suspension cultures of Arabidopsis thaliana (L.) Heynh cells obtained from seeds of plants with altered (reduced (AS-12 line) and increased (XX-2 line)) expression of the alternative oxidase gene AOX1a and studied their viability under subzero temperature (-10 °С for 3, 6, 9 hours). Cell viability and reactive oxygen species (ROS) production were assessed using fluorescence microscopy with fluorescein diacetate (FDA) and propidium iodide (PI) for cell viability measurement and H2DCF-DA for ROS measurement. The proportion of living cells was calculated as the proportion of FDApositive and PI-negative cells. Differences between the studied lines were determined in the content of mitochondrial proteins of the respiratory chain (AOX, COXII, NDB) and uncoupling protein (UCP), as well as in the intensity of formation of ROS and frost resistance. The obtained results confirmed the higher content of the AOX protein and its high contribution to mitochondrial respiration in line XX-2. Suspension culture cells of the AS-12 line showed a decrease in the AOX protein content and its contribution to mitochondrial respiration, compared to the wild type (Col-0) and line XX-2. Simultaneously with a decrease in the AOX protein content in the AS-12 cell culture, an increase in the content of the uncoupling protein UCP and subunit II of cytochrome oxidase (COXII) was observed. ROS generation was reduced in cell cultures of both XX-2 and AS-12. The obtained results indicate that the cells of the wildtype (Col-0) suspension culture were subjected to the most significant effect of subzero temperature. Long-term exposure (for 9 h) under -10 °С revealed significant differences in the viability of wild-type culture cells and lines with altered AOX1a gene expression. Cells of line XX-2 with an increased content of AOX turned out to be more resistant to subzero temperature compared to wild-type and AS-12 cells. However, while the proportion of living cells in the culture of the AS-12 line 48 h after exposure remained at the same level as immediately after it, in the suspension culture of the wild type cell death developed over time. The obtained results indicate the importance of alternative oxidase in the development of frost resistance in plant cell.

Stress-Induced Changes in Ubiquinone Concentration and Alternative Oxidase in Plant Mitochondria

2001 ◽  
Vol 21 (3) ◽  
pp. 369-379 ◽  
Author(s):  
Vasily N. Popov ◽  
Albert C. Purvis ◽  
Vladimir P. Skulachev ◽  
Anneke M. Wagner
Keyword(s):  
Alternative Oxidase ◽  
Respiratory Activity ◽  
Plant Mitochondria ◽  
High Oxygen ◽  
Plant Tissues ◽  
Respiration Rates ◽  
Bell Peppers ◽  
Respiration Of Mitochondria ◽  
Induced Changes

We have investigated the influence of stress conditions such as incubation at 4°C and incubation in hyperoxygen atmosphere, on plant tissues. The ubiquinone (Q) content and respiratory activity of purified mitochondria was studied. The rate of respiration of mitochondria isolated from cold-treated green bell peppers (Capsicum annuum L) exceeds that of controls, but this is not so for mitochondria isolated from cold-treated cauliflower (Brassica oleracea L). Treatment with high oxygen does not alter respiration rates of cauliflower mitochondria. Analysis of kinetic data relating oxygen uptake with Q reduction in mitochondria isolated from tissue incubated at 4°C (bell peppers and cauliflowers) and at high oxygen levels (cauliflowers) reveals an increase in the total amount of Q and in the percentage of inoxidizable QH2. The effects are not invariably accompanied by an induction of the alternative oxidase (AOX). In those mitochondria where the AOX is induced (cold-treated bell pepper and cauliflower treated with high oxygen) superoxide production is lower than in the control. The role of reduced Q accumulation and AOX induction in the defense against oxidative damage is discussed.

The alternative oxidases: simple oxidoreductase proteins with complex functions

2013 ◽  
Vol 41 (5) ◽  
pp. 1305-1311 ◽  
Author(s):  
Luke Young ◽  
Tomoo Shiba ◽  
Shigeharu Harada ◽  
Kiyoshi Kita ◽  
Mary S. Albury ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Transport ◽  
Alternative Oxidase ◽  
Structural Features ◽  
Transport Proteins ◽  
Integral Membrane Proteins ◽  
Complex Functions ◽  
Membrane Bound ◽  
Iron Carboxylate ◽  
Electron Transport Proteins

The alternative oxidases are membrane-bound monotopic terminal electron transport proteins found in all plants and in some agrochemically important fungi and parasites including Trypansoma brucei, which is the causative agent of trypanosomiasis. They are integral membrane proteins and reduce oxygen to water in a four electron process. The recent elucidation of the crystal structure of the trypanosomal alternative oxidase at 2.85 Å (1 Å=0.1 nm) has revealed salient structural features necessary for its function. In the present review we compare the primary and secondary ligation spheres of the alternative oxidases with other di-iron carboxylate proteins and propose a mechanism for the reduction of oxygen to water.

Plant respiration in a high CO2 world: How will alternative oxidase respond to future atmospheric and climatic conditions?

2014 ◽  
Vol 94 (6) ◽  
pp. 1091-1101 ◽  
Author(s):  
Jia Wang ◽  
Melissa Cheung ◽  
Lara Rasooli ◽  
Sasan Amirsadeghi ◽  
Greg C. Vanlerberghe
Keyword(s):  
Climate Change ◽  
Water Availability ◽  
Alternative Oxidase ◽  
Climatic Factors ◽  
Plant Mitochondria ◽  
Climatic Conditions ◽  
Carbon Gain ◽  
Energy Yield ◽  
Combined Processes ◽  
Plant Respiration

Wang, J., Cheung, M., Rasooli, L., Amirsadeghi, S. and Vanlerberghe, G. C. 2014. Plant respiration in a high CO2 world: How will alternative oxidase respond to future atmospheric and climatic conditions? Can. J. Plant Sci. 94: 1091–1101. Plant mitochondria contain an alternative oxidase (AOX) that reduces the energy yield of respiration. While respiration and photosynthesis are known to interact, the role of AOX in the light remains poorly understood. This gap in our understanding of leaf metabolism extends to future conditions of high CO2 and climate change. While studies indicate that AOX respiration is quite responsive to growth conditions, few studies have examined AOX respiration at high CO2 and little is known regarding the combined impact of changes in both CO2 and other climatic factors such as temperature and water availability. Given its non-energy conserving nature, a fundamental response by AOX to these future conditions could impact the net carbon gain that results from the combined processes of photosynthesis and respiration. Here, we show that leaf AOX protein amount in Nicotiana tabacum is dependent upon growth irradiance and CO2 level, that AOX is subject to biochemical control by intermediates of photorespiration, and that photosynthesis is impacted in transgenic plants lacking AOX. We also review findings that tobacco AOX respiration is responsive to climatic variables (temperature, water availability), thus providing an excellent experimental system to investigate the interplay between AOX, photosynthesis at high CO2, and climate change.

Structure and Function of the Plant Alternative Oxidase: Its Putative Role in the Oxygen Defence Mechanism

1997 ◽  
Vol 17 (3) ◽  
pp. 319-333 ◽  
Author(s):  
Anneke M. Wagner ◽  
Anthony L. Moore
Keyword(s):  
Oxidative Stress ◽  
Alternative Oxidase ◽  
Structure And Function ◽  
Current Understanding ◽  
Defence Mechanism ◽  
Putative Role ◽  
And Function

Current understanding of the structure and function of the plant alternative oxidase is reviewed. In particular, the role of the oxidase in the protection of tissues against oxidative stress is developed.

A Comparison of the Respiratory Processes and Growth Rate of Selected Australian Alpine and Related Lowland Plant Species

1990 ◽  
Vol 17 (5) ◽  
pp. 517 ◽  
Author(s):  
OK Atkin ◽  
DA Day
Keyword(s):  
Growth Rates ◽  
Alternative Oxidase ◽  
Geographical Origin ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Alternative Pathways ◽  
Respiration Rates ◽  
Whole Plant ◽  
Two Temperatures ◽  
Plant Respiration

Respiratory processes and growth rates of alpine and lowland species of three genera (Ranunculus, Plantago and Luzula) were compared. Relative growth rates were determined for the first 14 weeks of growth at two temperatures (7-10°C and 12-15°C). Generally, the relative growth rates of the alpine species were lower than those of their lowland relatives. Whole-plant respiration rates were measured and leaf slices from each species were used for a detailed analysis of respiratory pathways. Major differences were found between genera, particularly in their alternative oxidase activity, but respiratory patterns (both whole-plant respiration rates and the relative rates of cytochrome and alternative pathways in leaf slices) were maintained within a given genus, independent of the environmental or geographical origin of each species from that genus. The lack of correlation between growth rates and respiration rates suggests that the alpine plants used their respiratory products less efficiently than did the lowland species.

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