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Biophysical and biochemical constraints imposed by salt stress: learning from halophytes.

Duarte B, Sleimi N, Caçador I - Front Plant Sci (2014)

Bottom Line: Otherwise, the lack of adaptation to a salt environment would negatively affect their electron transduction pathways and the entire energetic metabolism, the foundation of every plant photosynthesis and biomass production.The maintenance of ionic homeostasis is in the basis of all cellular counteractive measures, in particular in terms of redox potential and energy transduction.In the present work the biophysical mechanisms underlying energy capture and transduction in halophytes are discussed alongside with their relation with biochemical counteractive mechanisms, integrating data from photosynthetic light harvesting complexes, electron transport chains to the quinone pools, carbon fixation, and energy dissipation metabolism.

View Article: PubMed Central - PubMed

Affiliation: Centre of Oceanography, Faculty of Sciences, University of Lisbon Lisbon, Portugal ; Marine and Environmental Sciences Centre, Faculty of Sciences, University of Lisbon Lisbon, Portugal.

ABSTRACT
Soil salinization is one of the most important factors impacting plant productivity. About 3.6 billion of the world's 5.2 billion ha of agricultural dry land, have already suffered erosion, degradation, and salinization. Halophytes are typically considered as plants able to complete their life cycle in environments where the salt concentration is above 200 mM NaCl. Salinity adjustment is a complex phenomenon but essential mechanism to overcome salt stress, with both biophysical and biochemical implications. At this level, halophytes evolved in several directions, adopting different strategies. Otherwise, the lack of adaptation to a salt environment would negatively affect their electron transduction pathways and the entire energetic metabolism, the foundation of every plant photosynthesis and biomass production. The maintenance of ionic homeostasis is in the basis of all cellular counteractive measures, in particular in terms of redox potential and energy transduction. In the present work the biophysical mechanisms underlying energy capture and transduction in halophytes are discussed alongside with their relation with biochemical counteractive mechanisms, integrating data from photosynthetic light harvesting complexes, electron transport chains to the quinone pools, carbon fixation, and energy dissipation metabolism.

No MeSH data available.


Related in: MedlinePlus

Rapid transient OJIP curve calculated parameters (Phi P0, maximum yield of primary photochemistry; Phi E0, probability that an absorbed photon will move an electron into the ETC; N, the number of quinone turnovers until maximum fluorescence is attained; Sm, the number of electrons that flow from the quinones to the ETC) radar plot in field stressed (white) and non-stressed individuals (black) of S. fruticosa and H. portulacoides species (average values, N = 5).
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Figure 6: Rapid transient OJIP curve calculated parameters (Phi P0, maximum yield of primary photochemistry; Phi E0, probability that an absorbed photon will move an electron into the ETC; N, the number of quinone turnovers until maximum fluorescence is attained; Sm, the number of electrons that flow from the quinones to the ETC) radar plot in field stressed (white) and non-stressed individuals (black) of S. fruticosa and H. portulacoides species (average values, N = 5).

Mentions: A closer investigation of the photochemical mechanisms (Figure 6) shows that in S. fruticosa the salinity adverse effects are mostly felt at the quinone level, affecting both the electron flow from reduced quinone to the electron transport chain (ETC) and also the quinone pool (Sm). Sm and the quinone reduction turnover rate (N) were severely reduced (Figure 6), leading to an excessive accumulation of reduced compounds and low redox potential (Kalaji et al., 2011). In H. portulacoides, the negative effects driven by salt stress result in lower light use efficiencies (LUE) due to high amounts of dissipated energy (Rintamäki et al., 1995). In these individuals, alongside with a lower probability that an incident photon can initiate an electron transfer via the ETC there is also a reduced efficiency for a trapped electron to move further than the oxidized quinone. This leads to an inevitable reduction in the maximum yield of primary photochemical processes (Kalaji et al., 2011).


Biophysical and biochemical constraints imposed by salt stress: learning from halophytes.

Duarte B, Sleimi N, Caçador I - Front Plant Sci (2014)

Rapid transient OJIP curve calculated parameters (Phi P0, maximum yield of primary photochemistry; Phi E0, probability that an absorbed photon will move an electron into the ETC; N, the number of quinone turnovers until maximum fluorescence is attained; Sm, the number of electrons that flow from the quinones to the ETC) radar plot in field stressed (white) and non-stressed individuals (black) of S. fruticosa and H. portulacoides species (average values, N = 5).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4273624&req=5

Figure 6: Rapid transient OJIP curve calculated parameters (Phi P0, maximum yield of primary photochemistry; Phi E0, probability that an absorbed photon will move an electron into the ETC; N, the number of quinone turnovers until maximum fluorescence is attained; Sm, the number of electrons that flow from the quinones to the ETC) radar plot in field stressed (white) and non-stressed individuals (black) of S. fruticosa and H. portulacoides species (average values, N = 5).
Mentions: A closer investigation of the photochemical mechanisms (Figure 6) shows that in S. fruticosa the salinity adverse effects are mostly felt at the quinone level, affecting both the electron flow from reduced quinone to the electron transport chain (ETC) and also the quinone pool (Sm). Sm and the quinone reduction turnover rate (N) were severely reduced (Figure 6), leading to an excessive accumulation of reduced compounds and low redox potential (Kalaji et al., 2011). In H. portulacoides, the negative effects driven by salt stress result in lower light use efficiencies (LUE) due to high amounts of dissipated energy (Rintamäki et al., 1995). In these individuals, alongside with a lower probability that an incident photon can initiate an electron transfer via the ETC there is also a reduced efficiency for a trapped electron to move further than the oxidized quinone. This leads to an inevitable reduction in the maximum yield of primary photochemical processes (Kalaji et al., 2011).

Bottom Line: Otherwise, the lack of adaptation to a salt environment would negatively affect their electron transduction pathways and the entire energetic metabolism, the foundation of every plant photosynthesis and biomass production.The maintenance of ionic homeostasis is in the basis of all cellular counteractive measures, in particular in terms of redox potential and energy transduction.In the present work the biophysical mechanisms underlying energy capture and transduction in halophytes are discussed alongside with their relation with biochemical counteractive mechanisms, integrating data from photosynthetic light harvesting complexes, electron transport chains to the quinone pools, carbon fixation, and energy dissipation metabolism.

View Article: PubMed Central - PubMed

Affiliation: Centre of Oceanography, Faculty of Sciences, University of Lisbon Lisbon, Portugal ; Marine and Environmental Sciences Centre, Faculty of Sciences, University of Lisbon Lisbon, Portugal.

ABSTRACT
Soil salinization is one of the most important factors impacting plant productivity. About 3.6 billion of the world's 5.2 billion ha of agricultural dry land, have already suffered erosion, degradation, and salinization. Halophytes are typically considered as plants able to complete their life cycle in environments where the salt concentration is above 200 mM NaCl. Salinity adjustment is a complex phenomenon but essential mechanism to overcome salt stress, with both biophysical and biochemical implications. At this level, halophytes evolved in several directions, adopting different strategies. Otherwise, the lack of adaptation to a salt environment would negatively affect their electron transduction pathways and the entire energetic metabolism, the foundation of every plant photosynthesis and biomass production. The maintenance of ionic homeostasis is in the basis of all cellular counteractive measures, in particular in terms of redox potential and energy transduction. In the present work the biophysical mechanisms underlying energy capture and transduction in halophytes are discussed alongside with their relation with biochemical counteractive mechanisms, integrating data from photosynthetic light harvesting complexes, electron transport chains to the quinone pools, carbon fixation, and energy dissipation metabolism.

No MeSH data available.


Related in: MedlinePlus