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

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.

Salt-tolerant rootstock increases yield of pepper under salinity through maintenance of photosynthetic performance and sinks strength

“…Maintenance of shoot and root vigor is dependent mainly on photosynthetic capacity (Duarte et al, 2014;Penella et al, 2015). Photosynthetic activity remained unchanged in A/A25 plants under salt conditions compared to their controls and, therefore, also in the supply of photosynthates to plants, as confirmed by the absence of reduced plant growth.…”

Growth, chlorophyll fluorescence and mineral nutrition in the halophyte Tamarix gallica cultivated in combined stress conditions: Arsenic and NaCl

“…Additionally, T. gallica have an ability to dissipate excessive energy. This is one of the most common mechanisms by which halophytes overcome the accumulation of excessive reducing power, the primary source of ROS, avoiding this way the photo-destruction of the photosynthetic apparatus [54]. Gusman et al [49] showed the decrease in the quantum yield of photosynthetic electron transport and the electron transport rate followed by the increase in the non-photochemical quenching in lettuce plants treated with As, indicating that the most part of excitation energy was dissipated as non-photochemical process, probably as part of an internal protection mechanism of the photosynthetic apparatus, as suggested by Konrad et al [55].…”

Disentangling the photochemical salinity tolerance in Aster tripolium L.: connecting biophysical traits with changes in fatty acid composition

“…Additionally, ongoing climate change (increasing drought frequency and intensity, increased air temperature and salt water intrusion in coastal soils) must also be taken into account, as must the consequences (Duarte et al . ). Salt stress in glycophytes is associated with a reduction in leaf expansion, stomatal closure, reduced primary production, biomass losses and nutritional deficiencies, e.g .…”