Physiological and Biochemical Insights of Improved Salinity Tolerance in Limonium irtaense Through Recovery from Salt Exposure During Germination
Description
Limonium irtaense is a critically endangered and protected halophyte endemic to a coastal area north of Castellón, (Spain). Conservation efforts over the past decades have aimed to reinforce its natural populations and establish translocated populations in nearby regions. In this study, we assessed, for the first time, the soil characteristics of one remaining natural population and five translocated sites. Additionally, we examined the germination behaviour of seeds collected from one natural population under varying salinity levels (0, 50, 100, 200, and 300 mM NaCl), followed by recovery assays in distilled water for seeds that did not germinate under saline conditions. Seedlings were transplanted into pots containing a peat-vermiculite mix, and after one month, they were subjected to stress treatments by irrigation with water, 300 mM NaCl, or 600 mM NaCl for another month. Growth parameters (fresh weight, number of leaves, and water content of roots and leaves) were recorded. Leaves were analysed for photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids), osmolytes (proline, glycine betaine, total soluble sugars), oxidative stress markers (MDA, H₂O₂), non-enzymatic antioxidants (phenolics, flavonoids), and antioxidant enzyme activities (SOD, CAT, APX). Ion contents were measured in both roots and leaves. Soil analysis revealed comparable conditions between natural and translocated sites, with only one site showing higher salinity and organic matter, without negatively affecting plant performance. Salt treatments significantly influenced all growth parameters, with plant origin affecting only root and leaf fresh weights. Biochemical analyses indicated a strong treatment effect on photosynthetic pigments, proline, and monovalent ion concentrations, but minimal changes in oxidative stress markers. Notably, plants derived from control (non-saline) germination exhibited lower foliar K⁺ and proline levels under salt stress compared to those germinated under saline or recovery conditions. Overall, our results suggest that salt exposure during or prior to germination confers enhanced tolerance to salinity, as demonstrated by improved survival and biomass. The antioxidant system remained largely uninduced, indicating stress resilience. Proline accumulation and foliar potassium homeostasis emerged as key traits underpinning salt tolerance in seedlings from salt-primed seeds. These findings offer valuable insights into stress adaptation mechanisms in halophytes and provide practical guidelines for improving the conservation and translocation success of endangered plant species.
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Institutions
- Universitat Politecnica de ValenciaValenciana, Valencia