The growth and accumulation of osmotic solutes of the halophyte common glasswort (Salicornia europaea) under salinity conditions

Abstract

A halophyte, common glasswort (Salicornia europaea L.), showed no phytotoxic or deficiency symptom at 100 and 300 mM NaCl, whereas plant growth was stunted at 0, 500, and 700 mM NaCl. In addition, the water content was lower within the shoots at 0 mM NaCl, as compared with the range of NaCl treatments. Under NaCl treatment, Na+ levels increased in the shoot and the root, whereas the levels of other cations (K+, Ca2+, and Mg2+) decreased. Na+ accumulated to a greater amount in the shoot than it did in the root. At 0 mM NaCl, cations such as K+, Ca2+, and Mg2+ were highly accumulated, but Na+ was significantly reduced. Furthermore, the total free amino-acid content in the shoots was higher non non-NaCl treatments than it was in NaCl treatments. In particular, the proline levels showed marked increase at 500 and 700 mM NaCl. The increase in glycine betaine accumulation under NaCl conditions correlated to the increase of salinity, and the pattern corresponded to the induction of betaine aldehyde dehydrogenase (BADH) activity. Even though the BADH activity was lowest, more glycine betaine accumulated under non-NaCl condition than it did under NaCl conditions. These results indicate that Na+ is an essential element for the normal growth of common glasswort, and the accumulation of osmotic solutes, such as proline and glycine betaine, in cells occur under inhibitory NaCl concentrations.