Ranking of 11 coastal halophytes from salt marshes in northwest Turkey according their salt tolerance

Salt-affected soils with high electrolyte contents limit the development of the majority of plants and serve as a habitat only for such species (halophytes) that can survive the conditions. To date, there is still much that is unknown about the physiological mechanisms, including ion relationships, that make plants salt-resistant. The primary aim of this study was to evaluate a method of ranking plants for their salt tolerance. A total of 11 coastal halophytes of the Kavak Delta were evaluated for their ability to cope with different soil salinities. For this, electrical conductivities of soils (of up to 135 dS m(-1)) were recorded and a total of 100 plant samples, including plant roots, were taken from a depth of 0-15 cm in the soil. The halophytes were ranked in the following order from highest to moderate salt tolerance: Halocnemum strobilaceum >= Salicornia fragilis >= Arthrocnemum fruticosum = Suaeda prostrata >= Salsola kali = Petrosimonia brachiata >= Juncus maritimus = Aeluropus littoralis >= Halimione portulacoides = Limonium graecum >= Artemisia santonicum. The Na+/K+ ratios of leaves perfectly reflected the salinity tolerance ranking of all halophytic species examined. It proved possible to rank the salt tolerance of halophytes by assessment of the electrical conductivity of the soil in which they grew naturally; tolerance was well predicted by the Na+/K+ ratio in the shoots

Metabolic responses of sugar beet to the combined effect of root hypoxia and NaCl-salinity

Behr JH, Bednarz H, Gödde V, Niehaus K, Zorb C. Metabolic responses of sugar beet to the combined effect of root hypoxia and NaCl-salinity. Journal of plant physiology. 2021;267: 153545.The combined occurrence of salt stress and hypoxia leads to increased growth reduction and severe toxic effects compared to salt stress alone. In the present work, we analyzed the metabolic response of sugar beet (Beta vulgaris L.) to salt stress combined with hypoxia in roots as well as in young and mature leaves. B. vulgaris plants were grown in a hydroponic culture under low and high salt concentrations combined with normoxic and hypoxic conditions. A non-targeted metabolic approach was used to identify the biochemical pathways underlying the metabolic and physiological adaptation mechanisms. Young and mature leaves showed a similar metabolic response to salt stress alone and combined stresses, accumulating sugar compounds. Osmoprotectants such as proline and pinitol were accumulated under combined stress. Roots exposed to hypoxic conditions showed increased TCA (tricarboxylic acid cycle) intermediates levels such as succinate, fumarate and malate. During hypoxia, the concentration of free amino acids as well as intermediates of the GABA (gamma-aminobutyric acid) shunt increased in roots as well as in leaves. The combination of salt stress and hypoxia results in a severe stress response in roots and leaves. A partial flux of the TCA cycle linked with the GABA shunt might be activated during hypoxia to regain reduction equivalents. Copyright © 2021 Elsevier GmbH. All rights reserved