Involvement of Calcium and Calmodulin in Protein and Amino Acid Metabolism in Rice Roots under Anoxia

摘要

The pretreatment of rice roots for 1 h in aerobic conditions with the Ca2+-channel blockers ruthenium red (RR) and verapamil and the calmodulin (CaM) antagonistsN-(6-aminohexyl)-5-chloro-1-naphtylenesulfonamide (W-7) and trifluoperazine, induced during 3 h of anoxia: (i) inhibition of amino acid andγ-aminobutyric acid (Gaba) accumulation; (ii) a decline in the protein content; (iii) a release of amino acids and K+into the growth media. The calcium ionophore A23187 reversed these effects in RR-treated roots. Moreover, the aerobic pretreatment of rice roots with A23187 alone or CaCl2increased the accumulation of amino acids and Gaba. These data indicate that the Ca2+/CaM complex is involved in the transduction of an anaerobic signal by inhibiting proteolysis and solute release, and activating the Ca2+/CaM-dependent glutamate decarboxylase