NACL-INDUCED ACCUMULATION OF GLYCINEBETAINE IN 4 SUBTROPICAL HALOPHYTES FROM PAKISTAN

Variation in both the total content and the concentration of glycinebe taine in response to increasing soil salinity was studied in the salt- secreting Atriplex griffithii Meg., the leaf succulent Suaeda fruticos a (L.) Forssk., the stem succulent Haloxylon recurvum Bunge ex Boiss. and the osmotically adjusting desert grass Halopyrum mucronatum (L.) S tapf. collected From a subtropical maritime desert in Pakistan. Glycin ebetaine content (mmol kg(-1) dry weight) increased with increasing Na Cl in Atriplex griffithii, Haloxylon recurvum and Halopyrum mucronatum , but peaked at 600 mM NaCl for Suaeda fruticosa and declined thereaft er. Glycinebetaine concentration (mmol l(-1) tissue water) increased w ith increasing salinity in all four halophyte species and was sufficie ntly high to serve as an osmoticum in all cases.