Ca 2+ ‐Calmodulin is Involved in Betacyanin Accumulation Induced by Dark in C 3 Halophyte Suaeda salsa

The C 3 halophyte Suaeda salsa was used to investigate the roles of Ca 2+ , Ca 2+ channels, and calmodulin (CaM) in betacyanin metabolism. Seeds of S. salsa were cultured in both the dark and light for 3 days. The fresh weight and betacyanin content were much higher in S. salsa seedlings formed in the dark than in seedlings formed in the light. The addition of Ca 2+ to the half‐strength MS nutrient solution promoted betacyanin accumulation in the dark, whereas Ca 2+ depletion by EGTA suppressed the dark‐induced betacyanin accumulation in shoots of S. salsa . The Ca 2+ channel blocker LaCl 3 also inhibited dark‐induced betacyanin accumulation. The highest activity of CaM and the maximum betacyanin content decreased by 51% and 45%, respectively, in shoots of S. salsa seedlings treated with the potent CaM antagonist chlorpromazine in the dark. Furthermore, the other CaM antagonist N ‐(6‐aminohexyl)‐5‐chloro‐1‐naphthalenesulfonamide (W‐7) also inhibited the activity of CaM and dark‐dependent betacyanin accumulation, whereas its less active structural analog N ‐(6‐aminohexyl)‐1‐naphthalenesulfonamide (W‐5) had little effect on the responses to dark of S. salsa seedlings. These results suggest that Ca 2+ , Ca 2+ ‐regulated ion channels, and CaM play an important role in dark‐induced betacyanin accumulation in the shoots of the C 3 halophyte S. salsa .