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Molecular and Metabolic Aspects of Plant and Bacterial Salt Tolerance

Olsson, Peter LU (2005)
Abstract (Swedish)
Popular Abstract in Swedish

Salt ackumulering på jordbruksmark är en historisk såväl som ett av de potentiellt största problem som mänskor har haft och har. Forskare har undersökt och försökt lösa detta problem under en lång tid. Över 20 reviewer har publicerats om ämnet under de senaste fem åren.



I denna avhandling redogörs summariskt för utbredningen av salt stress i dagens jordbruk, samt de toxiska och skadliga effekterna av salt på växter och bakterier. Mer omfattande sammanställningar om osmotisk skyddande och potentiellt osmotiskt skyddande molekyler, glycin betaine (GB) och ?-aminbutyrate (GABA) ges. Dessutom pressenteras en översikt över modern microarray transkriptions analys teknik.

... (More)
Popular Abstract in Swedish

Salt ackumulering på jordbruksmark är en historisk såväl som ett av de potentiellt största problem som mänskor har haft och har. Forskare har undersökt och försökt lösa detta problem under en lång tid. Över 20 reviewer har publicerats om ämnet under de senaste fem åren.



I denna avhandling redogörs summariskt för utbredningen av salt stress i dagens jordbruk, samt de toxiska och skadliga effekterna av salt på växter och bakterier. Mer omfattande sammanställningar om osmotisk skyddande och potentiellt osmotiskt skyddande molekyler, glycin betaine (GB) och ?-aminbutyrate (GABA) ges. Dessutom pressenteras en översikt över modern microarray transkriptions analys teknik.



Det är allmänt accepterat att GB är en av de mest effektiva osmolyterna som hjälper organismer att motstå många sorters stress som inte har ett biologiskt ursprung såsom salt och kyla. En undersökning av GBs effekt på transkriptomet indikerade att GB kan ha effekter som påminner om växthormoner i Arabidopsis. Många gener med förhöjda transcribtionsnivåer på grund av GB behandling verkar ha en tillväxtinhiberande effekt på Arabidopsis. I Escherichia coli påverkar GB flera heat shock proteins transkriptions nivåer. Denna effekt stöder tidigare studier som föreslagit att GB kan verka som kemiska chaperon. GB påverkade också E. colis tillväxthastighet positivt i medium med höga salt halter och hjälpte hyperosmotisk chokade Arabidopsis att överleva.



GABA har tillskrivits flera viktiga funktioner för t.ex. salt och köld tolerans i växter. Dessa funktioner inkluderar: GABA kanske fungerar som en signaleringsmolekyl och GABA kan vara inblandad i skyddet mot reaktiva syremolekyler. Tobaksfröer transformerad med en calmodulin gen från oxe grodde snabbare på medium med höga salthalter jämfört med kontroll fröer. Dessa transgena tobaksfröer och groddar hade dessutom en högre transient nivåer av GABA under groningen. GABA producerade troligen med hjälp av Ca2+/calmodulin stimulerat glutamat decarboxylase. En analys av groningshastigheten på medier med olika tillsatser och kombinationer av NaCl, LaCl3, EGTA, CaCl2 och GABA och en analys av fria aminosyrors nivåer i utvecklade tobaksplantor chock behandlade med NaCl indikerade att GABA troligen inte fungerar som en osmolyt utan snarare som en signaleringsmolekyl i salt stressad tobak.



Det är väl belagt att höga salthalter i jord och vatten minskar syres löslighet. Därför undersöktes hemoglobin syntetiserande E. colis tillväxt egenskaper i medium med höga salthalter. E. coli som syntetiserade Vitreoscilla hemoglobin uppnådde en högre optisk cell densitet och hade en lägre nivå av fettsyra-peroxidation än kontroller. Dessa iakttagelser kan betyda att Vitreoscilla hemoglobin kan öka E. colis motståndskraft mot reaktiva syremolekyler in vivo under salt stress. (Less)
Abstract
Salt stress is one of the historically as well as potentially largest agriculture problem humans have faced. Researchers have investigated and tried to solve this problem for a long time. Over 20 reviews have been written on this topic the last five years.



In this thesis the extent of salt stress in today's agriculture, the toxic and damaging effects on plants and bacteria exposed to salt stress, and the molecular responses of plants and bacteria exposed to salt stress have been summarised. More extensive analysis on a osmo-protective and a potentially osmo-protective molecule, glycine betaine (GB) and -aminobutyric acid (GABA) are given. In addition, an overview of modern microarray transcription analysis technology is... (More)
Salt stress is one of the historically as well as potentially largest agriculture problem humans have faced. Researchers have investigated and tried to solve this problem for a long time. Over 20 reviews have been written on this topic the last five years.



In this thesis the extent of salt stress in today's agriculture, the toxic and damaging effects on plants and bacteria exposed to salt stress, and the molecular responses of plants and bacteria exposed to salt stress have been summarised. More extensive analysis on a osmo-protective and a potentially osmo-protective molecule, glycine betaine (GB) and -aminobutyric acid (GABA) are given. In addition, an overview of modern microarray transcription analysis technology is included.



GB is generally accepted as one of the most efficient osmolytes helping organisms to cope with several abiotic stresses such as salt and osmotic stress. An investigation on GBs influence on transcription indicated that GB may have properties resembling hormones in Arabidopsis. Many of the transcriptional effects by GB in Arabidopsis suggest that elevated internal levels of GB may inhibit growth. GB also influenced heat shock proteins transcription levels in NaCl stressed Escherichia coli. This effect support earlier findings that GB functions as a chemical chaperone. GB was also showed to improve growth rate of E. coli and enhance survival of hyperosmotically NaCl shocked Arabidopsis.



GABA has been assigned several potential roles important for abiotic stress tolerance such as: function as a signalling molecule, being involved in reactive oxygen species scavenging and being a signalling molecule. Tobacco transformed with a bovine calmodulin gene showed a faster germination on saline media compared to control. This transgenic tobacco also showed enhanced transient levels of GABA during germination. GABA may have been produced by Ca2+/calmodulin-stimulated glutamate decarboxylase. Analysis of germination on media containing combinations of NaCl, LaCl3, EGTA, CaCl2 and GABA in combination with analysis of free amino acid levels in NaCl shock treated mature tobacco plants suggest that GABA rather may work as a signalling molecule than as an osmolyte in salt stressed tobacco.



It is well established that high salt level containing soils and water solutions have decreased aeration properties. Therefore growth properties of E. coli expressing haemoglobin growing in high NaCl concentrations were investigated. It was found that E. coli expressing Vitreoscilla haemoglobin probably reached a higher cell density and showed a lower level of lipid peroxidation compared with control. This data suggest that Vitreoscilla haemoglobin may improve reactive oxygen species scavenging in vivo under salt stress. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Einset, John, Department of Plant and Environmental Sciences, Agricultural University of Norway, Ås, Norway
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Biotechnology, Bioteknik, metabolism, gamma-aminobutyric acid, Nicotiana tabacum, salinity, hypoxia, heamoglobin, microarray, glycine betaine, NaCl, GABA, Vitreoscilla, calmodulin, Esherichia coli, tobacco, Biokemi, Metabolism, Biochemistry, Arabidopsis
pages
125 pages
publisher
Department of Pure and Applied Biochemistry, Lund University
defense location
Hörsal B, Kemicentrum, Sölvegatan 39, LUND
defense date
2005-05-12 10:30
ISBN
91-628-6494-7
language
English
LU publication?
yes
id
52acc861-da26-41cc-99c0-cca7b10b4af5 (old id 544742)
date added to LUP
2007-10-13 12:55:07
date last changed
2016-09-19 08:45:10
@misc{52acc861-da26-41cc-99c0-cca7b10b4af5,
  abstract     = {Salt stress is one of the historically as well as potentially largest agriculture problem humans have faced. Researchers have investigated and tried to solve this problem for a long time. Over 20 reviews have been written on this topic the last five years.<br/><br>
<br/><br>
In this thesis the extent of salt stress in today's agriculture, the toxic and damaging effects on plants and bacteria exposed to salt stress, and the molecular responses of plants and bacteria exposed to salt stress have been summarised. More extensive analysis on a osmo-protective and a potentially osmo-protective molecule, glycine betaine (GB) and -aminobutyric acid (GABA) are given. In addition, an overview of modern microarray transcription analysis technology is included.<br/><br>
<br/><br>
GB is generally accepted as one of the most efficient osmolytes helping organisms to cope with several abiotic stresses such as salt and osmotic stress. An investigation on GBs influence on transcription indicated that GB may have properties resembling hormones in Arabidopsis. Many of the transcriptional effects by GB in Arabidopsis suggest that elevated internal levels of GB may inhibit growth. GB also influenced heat shock proteins transcription levels in NaCl stressed Escherichia coli. This effect support earlier findings that GB functions as a chemical chaperone. GB was also showed to improve growth rate of E. coli and enhance survival of hyperosmotically NaCl shocked Arabidopsis.<br/><br>
<br/><br>
GABA has been assigned several potential roles important for abiotic stress tolerance such as: function as a signalling molecule, being involved in reactive oxygen species scavenging and being a signalling molecule. Tobacco transformed with a bovine calmodulin gene showed a faster germination on saline media compared to control. This transgenic tobacco also showed enhanced transient levels of GABA during germination. GABA may have been produced by Ca2+/calmodulin-stimulated glutamate decarboxylase. Analysis of germination on media containing combinations of NaCl, LaCl3, EGTA, CaCl2 and GABA in combination with analysis of free amino acid levels in NaCl shock treated mature tobacco plants suggest that GABA rather may work as a signalling molecule than as an osmolyte in salt stressed tobacco.<br/><br>
<br/><br>
It is well established that high salt level containing soils and water solutions have decreased aeration properties. Therefore growth properties of E. coli expressing haemoglobin growing in high NaCl concentrations were investigated. It was found that E. coli expressing Vitreoscilla haemoglobin probably reached a higher cell density and showed a lower level of lipid peroxidation compared with control. This data suggest that Vitreoscilla haemoglobin may improve reactive oxygen species scavenging in vivo under salt stress.},
  author       = {Olsson, Peter},
  isbn         = {91-628-6494-7},
  keyword      = {Biotechnology,Bioteknik,metabolism,gamma-aminobutyric acid,Nicotiana tabacum,salinity,hypoxia,heamoglobin,microarray,glycine betaine,NaCl,GABA,Vitreoscilla,calmodulin,Esherichia coli,tobacco,Biokemi,Metabolism,Biochemistry,Arabidopsis},
  language     = {eng},
  pages        = {125},
  publisher    = {ARRAY(0x9232110)},
  title        = {Molecular and Metabolic Aspects of Plant and Bacterial Salt Tolerance},
  year         = {2005},
}