Salt Tolerance of In vitro Activity of Leucine Aminopeptidase, Peroxidase, and Malate Dehydrogenase in the Halophytes Spartina alterniflora and S. patens

The salt tolerance of leucine aminopeptidase (LAP), peroxidase (PER), and malate dehydrogenase (MDH) was compared in leaf extracts of Spartina patens and the tall and short forms of S alterniflora. No significant differences were observed between the two forms of S. alterniflora, but in vitro activity of MDH and PER in S patens was more sensitive to NaCl than that in S. alterniflora The LAP from S. patens was significantly more active in salt-free medium than that of S. alterniflora These data correlate well with the greater salt tolerance of S. alterniflora and suggest that the salinity ranges of the two species may be due in part to differences in enzyme sensitivity. The MDH also was much more salt sensitive than PER and LAP in both species This may relate to LAP and PER being found in saltier cellular compartments than MDH.