EFFECTS OF NACL ON THE CARBOXYLATING ACTIVITY OF RUBISCO FROM TAMARIX-JORDANIS IN THE PRESENCE AND ABSENCE OF PROLINE-RELATED COMPATIBLESOLUTES

The effects of NaCl on the carboxylating activity of ribulose-1,5-bisp hosphate carboxylase/oxygenase (Rubisco) were investigated in the pres ence of two proline-related analogues found in Tamarix jordanis. N-met hyl-L-proline ameliorated the inhibition of the activity of Rubisco by NaCl. Full amelioration was reached at 200 mM of this protectant. Pro tection by N-methyl-trans-4-hydroxy-L-proline was less effective. Sign ificant differences in the Rubisco protein content from different popu lations of Tamarix jordanis were observed. Moreover, higher carboxylat ion rates were obtained for Rubisco preparations from plants that had been grown in saline media. These results are discussed with respect t o the adaptation strategies of Tamarix jordanis to saline conditions.