The effect of external Ca2+ and Ca(2+)-channel modulators on red-light-induced swelling of protoplasts of Phaseolus radiatus L.
Red-light-induced swelling of the protoplasts isolated from hypocotyl of etiolated mung bean (Phaseolus radiatus L.) was observed only when Ca2+ ions were present in the medium. The optimal CaCl2 concentration was 250 microM. Swelling response declined when Ca2+ was supplied into the medium after red light irradiation. The Ca(2+)-chelator EGTA eliminated the red-light-induced swelling and 45Ca2+ accumulation in the protoplasts. In contrast, A23187, a Ca(2+)-ionophore, could mimic the effect of red light in darkness. These results indicate that Ca2+ may play a role in light signal transduction. In addition, swelling response was prevented by TFP and CPZ (both are CaM antagonists), implying the involvement of CaM in red-light-induced and Ca(2+)-dependent protoplast swelling.
Long
C
C
Department of Biology, South China Normal University, Guangzhou, China.
Wang
X J
XJ
Pan
R C
RC
D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D002122:Calcium Chloride / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000502:physiology; D002413:Cations, Divalent; D048429:Cell Size / Q000528:radiation effects; D002614:Chelating Agents / Q000494:pharmacology; D002746:Chlorpromazine / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D007887:Fabaceae / Q000528:radiation effects*; D017136:Ion Transport / Q000528:radiation effects; D007476:Ionophores / Q000494:pharmacology; D008027:Light; D010946:Plants, Medicinal; D011523:Protoplasts / Q000528:radiation effects*; D015398:Signal Transduction; D014268:Trifluoperazine / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002147:Calmodulin; D002413:Cations, Divalent; D002614:Chelating Agents; D007476:Ionophores; D014268:Trifluoperazine; D000001:Calcimycin; D004533:Egtazic Acid; D002122:Calcium Chloride; D002118:Calcium; D002746:Chlorpromazine