Soil salinity is an abiotic stress that reduces agricultural productivity. For decades, halophytes have been studied to elucidate the physiological and biochemical processes involved in alleviating cellular ionic imbalance and conferring salt tolerance. Recently, several interesting genes with proven influence on salt tolerance were isolated from the Mediterranean halophyte Lobularia maritima (L.) Desv. A better understanding of salt response in this species is needed to exploit its potential as a source of stress-related genes. We report the characterisation of L. maritima’s response to increasing NaCl concentrations (100–400 mM) at the physiological, biochemical and molecular levels. L. maritima growth was unaffected by salinity up to 100 mM NaCl and it was able to survive at 400 mM NaCl without exhibiting visual symptoms of damage. Lobularia maritima showed a Na+ and K+ accumulation pattern typical of a salt-includer halophyte, with higher contents of Na+ in the leaves and K+ in the roots of salt-treated plants. The expression profiles of NHX1, SOS1, HKT1, KT1 and VHA-E1 in salt-treated plants matched this Na+ and K+ accumulation pattern, suggesting an important role for these transporters in the regulation of ion homeostasis in leaves and roots of L. maritima. A concomitant stimulation in phenolic biosynthesis and antioxidant enzyme activity was observed under moderate salinity, suggesting a potential link between the production of polyphenolic antioxidants and protection against salt stress in L. maritima. Our findings indicate that the halophyte L. maritima can rapidly develop physiological and antioxidant mechanisms to adapt to salt and manage oxidative stress.

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responses that involve antioxidant enzymes and molecules, rather than isolated responses of these antioxidants to salt stress.

Lobularia maritima or sweet alyssum (Brassicaceae) is an annual littoral halophyte, naturally thriving on sandy beaches. In addition to its obvious interest as a naturally salt-tolerant plant, this species is mainly cultivated as an ornamental plant in many countries. Laboratory experiments were carried out to assess the effects of salinity on seed germination and on germination recovery from the effects of saline conditions after transfer to distilled water. Seed germination responses were determined at 0, 50, 100, 200 and 300 mM NaCl. Salt (NaCl) does not affect the germination of L. maritima if applied at a moderate dose of 50 mM. For higher concentrations of NaCl, there is a decrease in the germination rate at 100 and 200 mM NaCl or even a total inhibition of germination at 300 mM. Salt lowers or inhibits germination only through osmotic effects. To improve the germination of L. maritima under high salinity, seeds were pretreated with KNO3, thiourea, proline and salicylic acid. The germination of seeds is improved by KNO3 in the presence or absence of salt, while thiourea increases the final germination without affecting the germination rate. Salicylic acid amplifies the effect of salt, while proline delays germination without stopping it completely. These findings indicate that the application of KNO3 and thiourea may be used to improve seed germination of L. maritima, which is of great interest for cultivating this plant for landscaping purposes in saline soils.