Abstract
Stomatal pores in the epidermis of plants function to enable gas exchange between plants and the atmosphere. Pairs of guard cells surround stomata. CO2 acts an environmental signal that regulates stomatal movements. To study the molecular processes that mediate CO2 signaling in guard cells, we have screened for mutants with altered CO2 responses using thermal imaging of leaves. Leaf temperature is a good indicator of stomatal aperture, since leaf temperature correlates with water transpiration rates due to evaporative cooling. We isolated a low-leaf-temperature mutant coin1 (CO2 insensitive 1 ) from approximately 5,000 individual activation tagged T4 lines of Arabidopsis thaliana ecotype Columbia (Col-0). coin1 did not exhibit stomatal closing in response to high CO2 concentration (700 ppm) but abscisic acid and dark triggered normal stomatal closure. Positional cloning of coin1 is in progress.
