Physiological and morphological characterisation of Limonium species in their natural habitats: Insights into their abiotic stress responses

Abstract

Background and aims Morphological and biochemical traits of four halophytes of the genus Limonium were analysed in plants sampled from salt marshes in SE Spain. This work aimed to explore the mechanism(s) behind the adaptation of these species to stressful habitats, with particular emphasis on responses to drought.Methods Plants of each species together with soil samples were collected in summer, which is the most stressful season in the Mediterranean. Soil parameters and plant morphological traits were determined, and the levels of several biochemical stress markers in plants were measured using spectrophotometric assays. A multivariate analysis was performed to correlate soil and plant data. Results Morphological characteristics regarding the underground system topology and several biochemical traits (higher foliar Ca 2+ , sucrose and glucose, and lower proline, glycine-betaine and fructose) clearly separate L. santapolense individuals from plants of the other three species. Conclusions Drought tolerance of L. santapolense in the field is mostly dependent on morphological adaptations: when growing in an arid location, plants of this species develop long taproots that can extract water from the deep, moist layers of the soil.

Responses to Increased Salinity and Severe Drought in the Eastern Iberian Endemic Species Thalictrum maritimum (Ranunculaceae), Threatened by Climate Change

“…In contrast, even though T. maritimum is present in low-salinity zones of the salt marshes, the biochemical analysis of its responses to salt stress highlighted that the species has many attributes of typical halophytes; most important, its primary mechanism of tolerance appears to be based on the active transport of toxic ions to the aboveground organs of the plants. The concentrations of Na + and Cl − increased in all organs in parallel to the increase of the concentration of NaCl in the irrigation solution, but the ions accumulated mostly in the foliar tissue, as reported in many salt-tolerant plants (e.g., [ 28 , 29 , 30 ]). Accumulation of inorganic ions as ‘cheap’ osmotica (in terms of energy consumption), is a widespread strategy of tolerance in halophytes [ 31 , 32 ].…”

“…Registered soil moisture values were above those reported in other studies in the same area [ 26 , 27 ]. The percentage of organic matter in T. maritimum locations was also higher than that reported for soils with sand texture from other salt marshes in the Natural Park of Albufera [ 28 ].…”

Root Morphology and Rhizosphere Characteristics Are Related to Salt Tolerance of Suaeda salsa and Beta vulgaris L.

“…For suaeda, the shoot/root ratio was significantly lower under high salinity than under lower salinity ( p < 0.05), suggesting that this halophyte might reinforce certain root traits to promote salt resistance of below-ground parts. An adjustment in biomass allocation as an adaptive strategy to salt stress would ensure the growth of halophytes ( Yuan et al, 2010 ; González-Orenga et al, 2020 ).…”

“…Roots are the organ with the most direct exposure to salinity, and their structure and function are one of the main features in the life cycle of halophytes ( Shabala et al, 2015 ; González-Orenga et al, 2020 ). The root systems of many species exhibit morphological plasticity, which increases the ratio of fine roots and improves the contact area so that they can absorb more nutrients in low-nutrient soils ( Zhang et al, 2010 ; Li et al, 2014 ; Mai et al, 2018 ).…”

“…The patterns of salt distribution in the soil strongly affect the spatial distribution of plants, as well as the configuration, length, and size of their root systems. High salinity affects their root morphological traits and restricts the growth of halophytes ( Song, 2009 ; González-Orenga et al, 2020 ). The roots of halophytes responded directly to sodium (Na + ) and chlorine (Cl − ) ions are obviously affected by other soil characteristics.…”