Maintenance respiration (or maintenance energy) refers to

metabolism Metabolism (, from ''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 cellular processes; the co ...

occurring in an

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

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 the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s refers to the amount of

cellular respiration Cellular respiration is the process of oxidizing biological fuels using an inorganic electron acceptor, such as oxygen, to drive production of adenosine triphosphate (ATP), which stores chemical energy in a biologically accessible form. Cell ...

, measured by the

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

(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 N ...

, 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 ade ...

) 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 residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

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. Bi ...

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), ...

) 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 system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

(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 ...

) 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