Ca2+‐Calmodulin is Involved in Betacyanin Accumulation Induced by Dark in C3 Halophyte Suaeda salsa

Abstract

Abstract The C3 halophyte Suaeda salsa was used to investigate the roles of Ca2+, Ca2+ 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 Ca2+ to the half‐strength MS nutrient solution promoted betacyanin accumulation in the dark, whereas Ca2+ depletion by EGTA suppressed the dark‐induced betacyanin accumulation in shoots of S. salsa. The Ca2+ channel blocker LaCl3 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 Ca2+, Ca2+‐regulated ion channels, and CaM play an important role in dark‐induced betacyanin accumulation in the shoots of the C3 halophyte S. salsa.