Abstract
Leaf temperature provides a convenient indicator of the transpiration, and can be used to detect phenotype of mutants with altered stomatal control. We screened mutants impaired in CO2-dependent leaf temperature change from approximately 1,0000 EMS-mutagenized Arabidopsis M2 population. Until now, three genetically separable mutants, designated as cdi1, cdi2, and cdi3 (cdi ;carbon dioxide insensitive), have been isolated. We characterized cdi3 in detail. In this mutant, high CO2 induced leaf temperature change and stomatal closing were inhibited. Abscisic acid (ABA) is another signaling component related to stomatal movement. The cdi3 stomata failed to close in response to ABA. Genetic mapping located the cdi3 locus in the upper arm of Chromosome 1. In this genomic region, we did not found any previously known ABA insensitive mutant locus. These results suggest that the CDI3 gene product may be involved in both CO2 and ABA signaling cascades.
