Carbon dioxide induces increases in guard cell cytosolic free calcium

✍ Scribed by Alex A.R. Webb; Martin R. McAinsh; Terry A. Mansfield; Alistair M. Hetherington

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 651 KB
• Volume: 9
• Category: Article
• ISSN: 0960-7412
• DOI: 10.1046/j.1365-313x.1996.09030297.x

✦ Synopsis

The hypothesis that increases in cytosolic free calcium ([Ca^2+^]~i~) are a component of the CO~2~ signal transduction pathway in stomatal guard cells of Commelina communis has been investigated. This hypothesis was tested using fura‐2 fluorescence ratio photometry to measure changes in guard cell [Ca^2+^]~i~ in response to challenge with 700 µl l^−1^ CO~2~. Elevated CO~2~ induced increases in guard cell [Ca^2+^]~i~ which were similar to those previously reported in response to abscisic acid. [Ca^2+^]~i~ returned to resting values following removal of the CO~2~ and further application of CO~2~ resulted in a second increase in [Ca^2+^]~i~. This demonstrated that the CO~2~‐induced increases in [Ca^2+^]~i~ were stimulus dependent. Removal of extracellular calcium both prevented the CO~2~‐induced increase in [Ca^2+^]~i~ and inhibited the associated reduction in stomatal aperture. These data suggest that Ca^2+^ acts as a second messenger in the CO~2~ signal transduction pathway and that an increase in [Ca^2+^]~i~ may be a requirement for the stomatal response to CO~2~.