Characterization of Arabidopsis high leaf temperature mutants with altered response to CO₂.

Abstract

Leaf temperature provides an indicator of the transpiration of plants, because evaporation of water causes leaf cooling. Atmospheric CO₂ concentrations are predicted to affect stomatal apertures and transpiration. To investigate the CO₂ signalling mechanism of plants, we isolated two novel Arabidopsis mutants (ht1 and ht2) which have an altered dependence of leaf temperature on CO₂ concentration. The ht1 is hyper sensitive to the change of CO₂ concentration. In contrast, ht2 is relatively insensitive to the change of CO₂ concentration. Stomatal conductance and stomatal aperture of ht1 and ht2 were lower level compared with those of the wild type under low CO₂ concentration. These results indicate that ht1 and ht2 are deficient in stomatal response to CO₂.