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Halotolerance

Halotolerance is the adaptation of living organisms to conditions of high salinity.[1] Halotolerant species tend to live in areas such as hypersaline lakes, coastal dunes, saline deserts, salt marshes, and inland salt seas and springs. Halophiles are organisms that live in highly saline environments, and require the salinity to survive, while halotolerant organisms (belonging to different domains of life) can grow under saline conditions, but do not require elevated concentrations of salt for growth. Halophytes are salt-tolerant higher plants. Halotolerant microorganisms are of considerable biotechnological interest.[2]

Applications edit

Fields of scientific research relevant to halotolerance include biochemistry, molecular biology, cell biology, physiology, ecology, and genetics.

An understanding of halotolerance can be applicable to areas such as arid-zone agriculture, xeriscaping, aquaculture (of fish or algae), bioproduction of desirable compounds (such as phycobiliproteins or carotenoids) using seawater to support growth, or remediation of salt-affected soils. In addition, many environmental stressors involve or induce osmotic changes, so knowledge gained about halotolerance can also be relevant to understanding tolerance to extremes in moisture or temperature.

Goals of studying halotolerance include increasing the agricultural productivity of lands affected by soil salination or where only saline water is available. Conventional agricultural species could be made more halotolerant by gene transfer from naturally halotolerant species (by conventional breeding or genetic engineering) or by applying treatments developed from an understanding of the mechanisms of halotolerance. In addition, naturally halotolerant plants or microorganisms could be developed into useful agricultural crops or fermentation organisms.

Cellular functions in halophytes edit

Tolerance of high salt conditions can be obtained through several routes. High levels of salt entering the plant can trigger ionic imbalances which cause complications in respiration and photosynthesis, leading to reduced rates of growth, injury and death in severe cases. To be considered tolerant of saline conditions, the protoplast must show methods of balancing the toxic and osmotic effects of the increased salt concentrations. Halophytic vascular plants can survive on soils with salt concentrations around 6%, or up to 20% in extreme cases. Tolerance of such conditions is reached through the use of stress proteins and compatible cytoplasm osmotic solutes.[3]

To exist in such conditions, halophytes tend to be subject to the uptake of high levels of salt into their cells, and this is often required to maintain an osmotic potential lower than that of the soil to ensure water uptake. High salt concentrations within the cell can be damaging to sensitive organelles such as the chloroplast, so sequestration of salt is seen. Under this action, salt is stored within the vacuole to protect such delicate areas. If high salt concentrations are seen within the vacuole, a high concentration gradient will be established between the vacuole and the cytoplasm, leading to high levels of energy investment to maintain this state. Therefore, the accumulation of compatible cytoplasmic osmotic solutes can be seen to prevent this situation from occurring. Amino acids such as proline accumulate in halophytic Brassica species, quaternary ammonium bases such as Glycine Betaine and sugars have been shown to act in this role within halophytic members of Chenopodiaceae and members of Asteraceae show the buildup of cyclites and soluble sugars. The buildup of these compounds allow for the balancing of the osmotic effect while preventing the establishment of toxic concentrations of salt or requiring the maintenance of high concentration gradients.[citation needed]

Bacterial halotolerance edit

The extent of halotolerance varies widely amongst different species of bacteria.[4] A number of cyanobacteria are halotolerant; an example location of occurrence for such cyanobacteria is in the Makgadikgadi Pans, a large hypersaline lake in Botswana.[5]

Fungal halotolerance edit

Fungi from habitats with high concentration of salt are mostly halotolerant (i.e. they do not require salt for growth) and not halophilic. Halophilic fungi are a rare exception.[6] Halotolerant fungi constitute a relatively large and constant part of hypersaline environment communities, such as those in the solar salterns.[7] Well studied examples include the yeast Debaryomyces hansenii and black yeasts Aureobasidium pullulans and Hortaea werneckii.[8] The latter can grow in media without salt, as well as in almost saturated NaCl solutions. To emphasize this unusually wide adaptability, some authors describe H. werneckii as "extremely halotolerant".[9]

See also edit

References edit

  1. ^ Walter Larcher (2001) Physiological Plant Ecology ISBN 3-540-43516-6
  2. ^ Margesin, R.; Schinner, F. (2001). "Potential of halotolerant and halophilic microorganisms for biotechnology". Extremophiles: Life Under Extreme Conditions. 5 (2): 73–83. doi:10.1007/s007920100184. PMID 11354458. S2CID 22371046.
  3. ^ Gupta, Bhaskar; Huang, Bingru (3 April 2014). "Mechanism of Salinity Tolerance in Plants: Physiological, Biochemical, and Molecular Characterization". International Journal of Genomics. 2014: 701596. doi:10.1155/2014/701596. PMC 3996477. PMID 24804192.
  4. ^ Dieter Häussinger and Helmut Sies (2007) Osmosensing and Osmosignaling, Academic Press, 579 pages ISBN 0-12-373921-7
  5. ^ C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham
  6. ^ Gostinčar, C.; Grube, M.; De Hoog, S.; Zalar, P.; Gunde-Cimerman, N. (2010). "Extremotolerance in fungi: Evolution on the edge". FEMS Microbiology Ecology. 71 (1): 2–11. doi:10.1111/j.1574-6941.2009.00794.x. PMID 19878320.
  7. ^ Zajc, J.; Zalar, P.; Plemenitaš, A.; Gunde-Cimerman, N. (2012). "The Mycobiota of the Salterns". Biology of Marine Fungi. Progress in Molecular and Subcellular Biology. Vol. 53. pp. 133–158. doi:10.1007/978-3-642-23342-5_7. ISBN 978-3-642-23341-8. PMID 22222830.
  8. ^ Gunde-Cimerman, N.; Ramos, J.; Plemenitaš, A. (2009). "Halotolerant and halophilic fungi". Mycological Research. 113 (11): 1231–1241. doi:10.1016/j.mycres.2009.09.002. PMID 19747974.
  9. ^ Gostinčar, C.; Lenassi, M.; Gunde-Cimerman, N.; Plemenitaš, A. (2011). Fungal Adaptation to Extremely High Salt Concentrations. Advances in Applied Microbiology. Vol. 77. pp. 71–96. doi:10.1016/B978-0-12-387044-5.00003-0. ISBN 9780123870445. PMID 22050822.

halotolerance, adaptation, living, organisms, conditions, high, salinity, halotolerant, species, tend, live, areas, such, hypersaline, lakes, coastal, dunes, saline, deserts, salt, marshes, inland, salt, seas, springs, halophiles, organisms, that, live, highly. Halotolerance is the adaptation of living organisms to conditions of high salinity 1 Halotolerant species tend to live in areas such as hypersaline lakes coastal dunes saline deserts salt marshes and inland salt seas and springs Halophiles are organisms that live in highly saline environments and require the salinity to survive while halotolerant organisms belonging to different domains of life can grow under saline conditions but do not require elevated concentrations of salt for growth Halophytes are salt tolerant higher plants Halotolerant microorganisms are of considerable biotechnological interest 2 Contents 1 Applications 2 Cellular functions in halophytes 3 Bacterial halotolerance 4 Fungal halotolerance 5 See also 6 ReferencesApplications editFields of scientific research relevant to halotolerance include biochemistry molecular biology cell biology physiology ecology and genetics An understanding of halotolerance can be applicable to areas such as arid zone agriculture xeriscaping aquaculture of fish or algae bioproduction of desirable compounds such as phycobiliproteins or carotenoids using seawater to support growth or remediation of salt affected soils In addition many environmental stressors involve or induce osmotic changes so knowledge gained about halotolerance can also be relevant to understanding tolerance to extremes in moisture or temperature Goals of studying halotolerance include increasing the agricultural productivity of lands affected by soil salination or where only saline water is available Conventional agricultural species could be made more halotolerant by gene transfer from naturally halotolerant species by conventional breeding or genetic engineering or by applying treatments developed from an understanding of the mechanisms of halotolerance In addition naturally halotolerant plants or microorganisms could be developed into useful agricultural crops or fermentation organisms Cellular functions in halophytes editTolerance of high salt conditions can be obtained through several routes High levels of salt entering the plant can trigger ionic imbalances which cause complications in respiration and photosynthesis leading to reduced rates of growth injury and death in severe cases To be considered tolerant of saline conditions the protoplast must show methods of balancing the toxic and osmotic effects of the increased salt concentrations Halophytic vascular plants can survive on soils with salt concentrations around 6 or up to 20 in extreme cases Tolerance of such conditions is reached through the use of stress proteins and compatible cytoplasm osmotic solutes 3 To exist in such conditions halophytes tend to be subject to the uptake of high levels of salt into their cells and this is often required to maintain an osmotic potential lower than that of the soil to ensure water uptake High salt concentrations within the cell can be damaging to sensitive organelles such as the chloroplast so sequestration of salt is seen Under this action salt is stored within the vacuole to protect such delicate areas If high salt concentrations are seen within the vacuole a high concentration gradient will be established between the vacuole and the cytoplasm leading to high levels of energy investment to maintain this state Therefore the accumulation of compatible cytoplasmic osmotic solutes can be seen to prevent this situation from occurring Amino acids such as proline accumulate in halophytic Brassica species quaternary ammonium bases such as Glycine Betaine and sugars have been shown to act in this role within halophytic members of Chenopodiaceae and members of Asteraceae show the buildup of cyclites and soluble sugars The buildup of these compounds allow for the balancing of the osmotic effect while preventing the establishment of toxic concentrations of salt or requiring the maintenance of high concentration gradients citation needed Bacterial halotolerance editThe extent of halotolerance varies widely amongst different species of bacteria 4 A number of cyanobacteria are halotolerant an example location of occurrence for such cyanobacteria is in the Makgadikgadi Pans a large hypersaline lake in Botswana 5 Fungal halotolerance editFungi from habitats with high concentration of salt are mostly halotolerant i e they do not require salt for growth and not halophilic Halophilic fungi are a rare exception 6 Halotolerant fungi constitute a relatively large and constant part of hypersaline environment communities such as those in the solar salterns 7 Well studied examples include the yeast Debaryomyces hanseniiand black yeasts Aureobasidium pullulans and Hortaea werneckii 8 The latter can grow in media without salt as well as in almost saturated NaCl solutions To emphasize this unusually wide adaptability some authors describe H werneckiias extremely halotolerant 9 See also editArabidopsis thaliana responses to salinity Biosalinity Use of salty water for irrigation Crop tolerance to seawater Crop tolerance to seawater is the ability of an agricultural crop to withstand the high salinity induced by irrigation with seawater Pages displaying wikidata descriptions as a fallback Salinity control Controlling the problem of soil salinityPages displaying short descriptions of redirect targets Salt tolerance of crops Sodium in biology Use of Sodium by organisms Soil salinity Salt content in the soil Soil salinity control Controlling the problem of soil salinityReferences edit Walter Larcher 2001 Physiological Plant Ecology ISBN 3 540 43516 6 Margesin R Schinner F 2001 Potential of halotolerant and halophilic microorganisms for biotechnology Extremophiles Life Under Extreme Conditions 5 2 73 83 doi 10 1007 s007920100184 PMID 11354458 S2CID 22371046 Gupta Bhaskar Huang Bingru 3 April 2014 Mechanism of Salinity Tolerance in Plants Physiological Biochemical and Molecular Characterization International Journal of Genomics 2014 701596 doi 10 1155 2014 701596 PMC 3996477 PMID 24804192 Dieter Haussinger and Helmut Sies 2007 Osmosensing and Osmosignaling Academic Press 579 pages ISBN 0 12 373921 7 C Michael Hogan 2008 Makgadikgadi The Megalithic Portal ed A Burnham Gostincar C Grube M De Hoog S Zalar P Gunde Cimerman N 2010 Extremotolerance in fungi Evolution on the edge FEMS Microbiology Ecology 71 1 2 11 doi 10 1111 j 1574 6941 2009 00794 x PMID 19878320 Zajc J Zalar P Plemenitas A Gunde Cimerman N 2012 The Mycobiota of the Salterns Biology of Marine Fungi Progress in Molecular and Subcellular Biology Vol 53 pp 133 158 doi 10 1007 978 3 642 23342 5 7 ISBN 978 3 642 23341 8 PMID 22222830 Gunde Cimerman N Ramos J Plemenitas A 2009 Halotolerant and halophilic fungi Mycological Research 113 11 1231 1241 doi 10 1016 j mycres 2009 09 002 PMID 19747974 Gostincar C Lenassi M Gunde Cimerman N Plemenitas A 2011 Fungal Adaptation to Extremely High Salt Concentrations Advances in Applied Microbiology Vol 77 pp 71 96 doi 10 1016 B978 0 12 387044 5 00003 0 ISBN 9780123870445 PMID 22050822 Retrieved from https en wikipedia org w index php title Halotolerance amp oldid 1186859579, wikipedia, wiki, book, books, library,

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