REGULAR ARTICLES

Cell Research (1998)8:41-50
© 1998 SIBS, CAS All rights reserved 1001-0602/98

The effect of external Ca2+ and Ca(2+)-channel modulators on red-light-induced swelling of protoplasts of Phaseolus radiatus L.

Department of Biology, South China Normal University, Guangzhou, China.

Correspondence: Long C E-mail: bioll@ecnu.edu.cn

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Abstract

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.

Keywords : Calcium ions, red light, protoplast swelling, 45Ca2+ accomulation, Phaseolus radiatus.