Diverse salinity responses in Crithmum maritimum tissues at different salinities over time

Abstract

Crithmum maritimum (sea fennel) withstands high salinity, and to better understand how different protective mechanisms against salinity are activated, young seedlings were exposed to increasing concentrations of NaCl (0 to 512 mM) over six weeks. Plant survival and chlorophyll content were reduced at > 85 mM NaCl and growth was affected at ≥ 341 mM NaCl. Relative water content fell and Na + accumulated more in leaves than in roots. Induction of Na + /H + antiporter expression reached a maximum at 427 mM NaCl in both tissues. Salinity induced the accumulation of proline, soluble sugars and glycine betaine. All three accumulated to higher levels in leaves than roots and greatest accumulation was after 6 weeks and the highest salt concentrations. Hydrogen peroxide levels fell with increasing salinity in leaves, while ascorbic acid and catalase activity rose. Overall, the most dramatic changes occurred after six weeks of saline stress but different mechanisms were activated at different salinity thresholds and in the two tissues. Key salinity thresholds in the response of Crithmum maritimum to salinity stress are identified activating different mechanisms. At 85 mM NaCl roots reach osmotic adjustment, at 171 mM further osmolyte protection mechanisms are activated, at 256 mM NaCl leaves reach osmotic adjustment, at 341 mM plant growth is affected and at the highest salinity tested, 512 mM, protective mechanisms are affected in leaves but not in roots.

Recycled Wastewater and Reverse Osmosis Brine Use for Halophytes Irrigation: Differences in Physiological, Nutritional and Hormonal Responses of Crithmum maritimum and Atriplex halimus Plants

“…This fact might explain that the plants did not suffer salt stress or that salinity was not high enough to cause the accumulation of SC. Some studies showed that Crithmum maritimum is able to maintain growth at high salinity levels, even up to 340 mM NaCl [77,78]. However, Ben Hamed et al [79] found that DW biomass of Crithmum begun to reduce even at 50 (4.5 dS m −1 ) mM NaCl.…”

An Experimental Brackish Aquaponic System Using Juvenile Gilthead Sea Bream (Sparus aurata) and Rock Samphire (Crithmum maritimum)

“…All experimental procedures were conducted according to the guidelines by the EU Directive 2010/63/EU regarding the protection of animals used for scientific purposes and were applied by FELASA accredited scientists (functions A-D). The two salinities were selected for the following two reasons: (a) 8 ppt is the optimal salinity for rock samphire growth performance [27,28] in hydroponic facilities and (b) 20 ppt is the maximum salinity for the survival and growth for rock samphire.…”

“…Rock samphire is a facultative halophyte, meaning that it can grow in a wide range of salinity levels. While it thrives when the irrigation water contains up to 250 mM NaCl, it exhibits reduced growth rates when the salinity exceeds this limit [28]. Nevertheless, rock samphire can survive in seawater [63].…”

“…Nevertheless, rock samphire can survive in seawater [63]. Previous studies indicated that the range of optimal performance in a hydroponics system occurs between 35 and 171 mM NaCl [28], which corresponds to approximately 1.8-10 ppt. This finding is consistent with our results, where the optimal growth of rock samphire occurred at 8 ppt salinity.…”

Application of exogenous xyloglucan oligosaccharides affects molecular responses to salt stress in Arabidopsis thaliana seedlings .

“…The chlorophyll content reduction is another consequence of salt stress in plants (Taïbi et al, 2016;Hamdani et al, 2017 (Sade et al, 2018). However, it is not possible to conclude whether down-regulation of CV expression is a direct effect of the XGOs.…”