Ionic Osmoregulation during Salt Adaptation of the Cyanobacterium <i>Synechococcus</i> 6311

Blumwald, Eduardo; Mehlhorn, Rolf J.; Packer, Lester

doi:10.1104/pp.73.2.377

Cited by 95 publications

(56 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The enhanced photosynthetic activity was essential to provide the energy demand for the process of salt adaptation which includes the biosynthesis of sugars for osmoregulation and efficient Na+ exclusion (4). The enhancement in photosynthetic activity observed during the 1st d of adaptation is only partially utilized for soluble sugar accumulation, and may provide the energetic demand for active Na+ extrusion (8).…”

Section: Cm-mentioning

confidence: 99%

See 1 more Smart Citation

Salt Adaptation of the Cyanobacterium Synechococcus 6311 Growing in a Continuous Culture (Turbidostat)

Blumwald

Tel‐Or²

1984

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

Physiological aspects of salt-adaptation in the cyanobacterium Synechococcus 6311 growing in a continuous culture (turbidostat) were studied. The process of salt-adaptation was completed within 3 days, as expressed by the specific growth rate of cells grown in the presence of 0.2 and 0.4 molar NaCl. An increase in photosynthetic activity during the adaptation period leads to the accumulation of soluble sugars, essential for osmoregulation in the salt-grown cells. Cells grown in the presence of 0.4 molar NaCI showed an initial inhibition in the rate of protein synthesis which was enhanced after the 1st day of salt stress. After adaptation, salt-grown cells showed an increase in phycobiliprotein synthesis and a higher phycobiliprotein to protein ratio. and illuminated with cool white fluorescent light, I = 20 mw/ cm-.Cell Parameters. Dry weight, Chl, protein, and phycobiliprotein content were determined as described previously (1) Cells were grown in a turbidostat as described in "Materials and Methods." NaCI was added after a constant specific growth rate was achieved.

show abstract

Section: Cm-mentioning

confidence: 99%

“…The salt stress challenges the energy requirement for the biosynthesis of soluble sugars, necessary for osmoregulation, and for active Na+ extrusion (4).…”

Section: Cm-mentioning

confidence: 99%

Salt Adaptation of the Cyanobacterium Synechococcus 6311 Growing in a Continuous Culture (Turbidostat)

Blumwald

Tel‐Or²

1984

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Salt acclimation in cyanobacteria occurs in five phases (Hagemann, 2011). A salt shock causes rapid shrinking of the cells due to loss of water (Blumwald et al, 1983) via aquaporins (Shapiguzov et al, 2005). In the second phase, ions including Na + and Cl 2 passively enter the cells and water flows back to the cells (Reed et al, 1985) but cellular processes including photosynthesis (Allakhverdiev et al, 2000) and gene expression (Hagemann et al, 1994;Fulda et al, 2006) remain slow due to high ion (especially Na + ) content of the cells.…”

mentioning

confidence: 99%

The SigB σ Factor Regulates Multiple Salt Acclimation Responses of the Cyanobacterium Synechocystis sp. PCC 6803

et al. 2011

View full text Add to dashboard Cite

Changing of principal s factor in RNA polymerase holoenzyme to a group 2 s factor redirects transcription when cyanobacteria acclimate to suboptimal environmental conditions. The group 2 sigma factor SigB was found to be important for the growth of the cyanobacterium Synechocystis sp. PCC 6803 in high-salt (0.7 M NaCl) stress but not in mild heat stress at 43°C although the expression of the sigB gene was similarly highly, but only transiently up-regulated at both conditions. The SigB factor was found to regulate many salt acclimation processes. The amount of glucosylglycerol-phosphate synthase, a key enzyme in the production of the compatible solute glucosylglycerol, was lower in the inactivation strain DsigB than in the control strain. Addition of the compatible solute trehalose almost completely restored the growth of the DsigB strain at 0.7 M NaCl. High-salt conditions lowered the chlorophyll and phycobilin contents of the cells while protective carotenoid pigments, especially zeaxanthin and myxoxanthophyll, were up-regulated in the control strain. These carotenoids were up-regulated in the DsigCDE strain (SigB is the only functional group 2 s factor) and down-regulated in the DsigB strain under standard conditions. In addition, the HspA heat shock protein was less abundant and more abundant in the DsigB and DsigCDE strains, respectively, than in the control strain in high-salt conditions. Some cellular responses are common to heat and salt stresses, but pretreatment with mild heat did not protect cells against salt shock although protection against heat shock was evident.

show abstract

“…NaCl directly inhibits the assemblage of the component proteins of nitrogenase by binding to Fe-protein. The inhibition of nitrogenase activity by NaCl in the Azolla fronds may be due to: (i) The disturbed electron transport (Tel-Or and Melhamed-Harel 1981), (ii) the disturbed plasmamembrane permeability (Blumwald et al 1983), and (iii) the inhibition in the photosynthetically generated ATP (Fernandez-Valiente et al 1984). …”

Section: Discussionmentioning

confidence: 99%

Physiological interactions inAzolla-Anabaenasystem adapting to the salt stress

Singh

Upadhyay

Mishra

2008

Journal of Plant Interactions

View full text Add to dashboard Cite

The effect of the different levels of salinity on some important physiological parameters among six species of Azolla has been investigated. Salinity reduced the growth (dry weight) and nitrogenase activity in AzollaAnabaena association while heterocyst frequency was sharply increased. Minimum sodium accumulation and electrolyte leakage (EL) was observed up to 20 mM NaCl whereas nitrate was accumulated significantly. Beyond 20 mM NaCl, fronds having higher amount of Na ' and EL inhibited the accumulation and reduction of nitrate suggests that 20 mM NaCl is the critical concentration. Highest superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and proline content might be the probable reason for the low level of EL, malondialdehyde (MDA) content and Na ' accumulation in Azolla species. Lower Na ' accumulation, solute leakage and lipid peroxidation along with the higher nitrogen demand and the proline accumulation with a high ability of oxygen radical scavenging in A. microphylla might be the reasons to grow at higher NaCl concentrations.Keywords: Azolla; salinity; antioxidants; electrolyte leakage; nitrate; proline IntroductionAzolla is a heterosporus, free floating, fast growing aquatic fern and is widespread in fresh water habitat of India, Sri Lanka, Japan, China and Philippines. The cyanobiont Anabaena azollae inhabits the leaf cavity of Azolla-Anabaena system and has the capacity to fulfill the total nitrogen demand of the association (Peters and Meeks 1989;Plazinski 1990). In comparison to the free-living cyanobacteria, Azolla association has several folds higher nitrogen fixation capacity and that is why the Azolla-Anabaena system is extensively used as a biofertilizer in rice and many other crops (Pabby et al. 2003;Nayak et al. 2004). However, salinity is a serious handicap for the cultivation and production of agricultural crops. High salinity not only affects the morphological, anatomical, developmental, physiological and biochemical processes of plants which can be observed in the form of plant productivity and/or as the death of the plants but also causes a water deficit condition, membrane disorganization and altered nutrition acquisition. This leads to the formation of reactive oxygen species (ROS) that disrupts normal metabolism through oxidative damage to the lipids (Wise and Naylor 1987) and to protein and nucleic acids (Imlay and Linn 1988). However, there is the ability in all the living systems, from bacteria to higher plants to adapt themselves to the osmotic stress with minor modifications. Plants always make various strategies to avoid the deleterious effect of NaCl (Munns et al. 2002;Parida and Das 2005). During the salt stress or adaptation towards salt, the usually associated mechanisms are major alteration in Na ' transport, i.e. influx and efflux. Salt-tolerant plants, besides involving in regulation of ion and water movements in the cells, also have an antioxidant system for effective removal of highly reactive oxygen species (ROS). It has been also reported that supe...

show abstract

Ionic Osmoregulation during Salt Adaptation of the Cyanobacterium Synechococcus 6311

Cited by 95 publications

References 11 publications

Salt Adaptation of the Cyanobacterium Synechococcus 6311 Growing in a Continuous Culture (Turbidostat)

Salt Adaptation of the Cyanobacterium Synechococcus 6311 Growing in a Continuous Culture (Turbidostat)

The SigB σ Factor Regulates Multiple Salt Acclimation Responses of the Cyanobacterium Synechocystis sp. PCC 6803

Physiological interactions inAzolla-Anabaenasystem adapting to the salt stress

Contact Info

Product

Resources

About