Effect of salinity on osmotic adjustment, glycinebetaine accumulation and the betaine aldehyde dehydrogenase gene expression in two halophytic plants, Salicornia europaea and Suaeda maritima

Salicornia europaea and Suaeda maritima plants were exposed to salinity stress, and leaf water status, solute concentrations in the cell sap, plant growth, and levels of betaine aldehyde dehydrogenase (BADH) mRNA were measured. Salicornia europaea was able to maintain a higher tugor and relative water content at low leaf water potentials which was associated with a greater capacity for osmotic adjustment. The major osmotica in Salicornia europaea leaves was Na + and glycine betaine and these solutes were increased by salinity. A similar tendency for the Na + and glycine betaine concentration was observed in Suaeda maritima leaves but at lower concentrations Suaeda maritima plants accumulated higher levels of proline in their leaves under salt stress than Salicornia europaea. Betaine aldehyde dehydrogenase gene expression (BADH mRNA) in Salicornia europaea and Suaeda maritima leaves increased with salt stress and the expression pattern coincided with the observed betaine accumulation.