Maintenance respiration (or maintenance energy) refers to

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

occurring in an

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

that is needed to maintain that organism in a healthy, living state. Maintenance respiration contrasts with growth respiration, which is responsible for the synthesis of new structures in growth, nutrient uptake, nitrogen (N) reduction and phloem loading, whereas maintenance respiration is associated with protein and membrane turnover and maintenance of ion concentrations and gradients.

In plants

Maintenance respiration in

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

s refers to the amount of

cellular respiration Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Cellular respiration may be des ...

, measured by the

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

(CO₂) released or oxygen (O₂) consumed, during the generation of usable energy (mainly ATP,

NADPH Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NAD ...

, and

NADH Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an aden ...

) and metabolic intermediates used for (i) resynthesis of compounds that undergo renewal (turnover) in the normal process of

(examples are enzymatic

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s, ribonucleic acids, and membrane lipids); (ii) maintenance of chemical gradients of ions and metabolites across cellular

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. B ...

s that are necessary for cellular integrity and plant health; and (iii) operation of metabolic processes involved in physiological adjustment (i.e.,

acclimation Acclimatization or acclimatisation ( also called acclimation or acclimatation) is the process in which an individual organism adjusts to a change in its environment (such as a change in altitude, temperature, humidity, photoperiod, or pH), a ...

) to a change in the plant's environment.Penning de Vries FWT (1975). "The cost of maintenance processes in plant cells", ''Annals of Botany'', 39:77-92.Lambers H, Szaniawski RK, de Visser R (1983). "Respiration for growth, maintenance and ion uptake. An evaluation of concepts, methods, values and their significance", ''Physiologia Plantarum'', 58:556-563.Amthor JS (2000). "The McCree--de Wit--Penning de Vries--Thornley Respiration Paradigms: 30 Years Later", ''Annals of Botany'', 86:1-20. The metabolic costs of the repair of injury from biotic or abiotic stress may also be considered a part of maintenance respiration. Maintenance respiration is essential for biological health and growth of plants. It is estimated that about half of the respiration carried out by terrestrial plants during their lifetime is for the support of maintenance processes.Amthor JS (1989). ''Respiration and Crop Productivity'', Springer-Verlag. Because typically more than half of global terrestrial plant

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

(or gross

primary production In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...

) is used for plant respiration, more than one quarter of global terrestrial plant photosynthesis is presumably consumed in maintenance respiration. Maintenance respiration is a key component of most physiologically based mathematical models of plant growth, including models of crop growth and yield and models of ecosystem primary production and carbon balance.Canell MGR, Thornley JHM (2000) "Modelling the components of plant respiration: some guiding principles". ''Annals of Botany'' 85:45-54.Amthor JS, and 12 others (2001). "Boreal forest CO₂ exchange and evapotranspiration predicted by nine ecosystem process models: intermodel comparisons and relationships to field measurements". ''Journal of Geophysical Research'' 106:33,623-33,648.Thornley JHM, France J (2007). ''Mathematical Models in Agriculture'', CABI, Wallingford, UK.

References

{{Reflist *Thornley JHM (1970). "Respiration, growth and maintenance in plants", ''Nature'', 35:721-728. *Pirt SJ (1965) "The maintenance energy of bacteria in growing cultures". ''Proceedings of the Royal Society of London, Series B'' 163:224-231. Cellular respiration Metabolism Plant physiology