Effects of NaCl on the carboxylating activity of Rubisco from Tamarix jordanis in the presence and absence of proline‐related compatible solutes

The effects of NaCl on the carboxylating activity of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) were investigated in the presence of two proline‐related analogues found in Tamarix jordanis. N‐methyl‐L‐proline ameliorated the inhibition of the activity of Rubisco by NaCl. Full amelioration was reached at 200 mM of this protectant. Protection by N‐methyl‐trans‐4‐hydroxy‐L‐proline was less effective. Significant differences in the Rubisco protein content from different populations of Tamarix jordanis were observed. Moreover, higher carboxylation rates were obtained for Rubisco preparations from plants that had been grown in saline media. These results are discussed with respect to the adaptation strategies of Tamarix jordanis to saline conditions.