NaCl homoeostasis as a factor for the survival of the evergreen halophyte Armeria maritima (Mill.) Willd. under salt stress in winter

Abstract

The combination of NaCl and low temperature stress makes winter a critical time for evergreen halophytes at temperate latitudes. As part of a study of ecotypic differentiation of the evergreen Armeria maritima (Mill.) Willd., inland and salt‐marsh populations were compared with respect to their growth and survival, osmotic adjustment and NaCl concentrations (based on dry weight) under salt stress in pot experiments in winter. Increased leaf necrosis in all populations under salt stress indicated a higher NaCl sensitivity in winter than in summer. Plants from inland populations were more sensitive than salt‐marsh populations. Inland and salt‐marsh populations showed similar capacities for seasonal osmotic adjustment, high seasonal increase of praline concentration and long‐term betaine accumulation. Inland and salt‐marsh populations allocated Na and Cl preferentially to the shoot. In inland populations, Na and Cl accumulated to high concentrations in leaves, whereas the much lower NaCl concentration in salt‐marsh populations suggested that in these plants, Na uptake was regulated to match the growth‐dependent ion demand of the shoot. The prevention of NaCl accumulation in times of slow growth by a NaCl homoeostasis system seemed to be an important adaptation with respect to the survival of evergreen plants in salt marshes.

Salinity Tolerance, Ion Accumulation Potential and Osmotic Adjustment In Vitro and In Planta of Different Armeria maritima Accessions from a Dry Coastal Meadow

“…Given high ecological variability of A. maritima accessions, two earlier studies addressed question on possible differences in adaptations of A. maritima to high soil salinity between different geographically and ecologically isolated micropopulations [ 35 , 37 ]. In general, both salt marsh and inland populations of A. maritima showed relatively high salinity tolerance, possibly related to the ability of plants to allocate Na + to leaves and to accumulate organic osmolytes.…”

Rapid determination of comparative drought tolerance traits: using an osmometer to predict turgor loss point

“…Methods have been described for measuring π o using a thermocouple psychrometer or osmometer (i.e. a psychrometer with Peltier cooling) (Turner 1981) for samples of extracted (expressed) sap from crushed leaf tissue (Wenkert 1980; Eldredge & Shock 1990; Morgan 1992), hot water extractions from dried leaf tissue (Kohl 1996, 1997) or discs of leaf tissue that have been rapidly frozen and thawed to break cell walls and release protoplasmic contents (Kikuta & Richter 1992a; Ball & Oosterhuis 2005; Callister, Arndt & Adams 2006). Previous work towards cross‐validating π o measurement methods found correlations between measurements made with the p–v curve and estimates based on psychrometry measurements of vacuolar fluid (Shackel 1987), and osmometer measurements of freeze‐thawed tissue, wherein leaf tissue is frozen to rupture cells and allow vapour pressure measurements based on evaporation from the cytoplasm (Nonami & Schulze 1989), although the choice of method influenced π o values (Ball & Oosterhuis 2005).…”

Comparison of four methods for measuring osmotic potential of tree leaves

“…Alternatives to expressing sap include hot water extraction. The osmolality of hot water extracts [( n / V ) HWE ] can be converted to leaf π at a given RWC and apoplastic water content (Kohl 1996, 1997). The potential advantage of HWE samples over those obtained using a press (ES) is that a consistent extract concentration and volume is obtained regardless of the leaf water status or sclerophylly.…”