Abstract
We have used forward genetic approach to isolate genes involved in CO2 responses in guard cells by screening for mutants with altered CO2 sensitivity through a high-throughput leaf thermal imaging. ht2 (high leaf temperature mutant 2) showed higher leaf temperature under low CO2 concentration, and altered in their ability to control stomatal movements in response to CO2. The ht2 also showed hypersensitivity in ABA induction of stomatal closure as well as ABA inhibition of seed germination. These suggest HT2 gene product is a component of the common signaling pathway of CO2 and ABA. Promoter-GUS analysis showed HT2 expressed in whole plant, especially in bundle sheath. Analysis of subcellular localization of HT2::GFP protein detected signals in cytosol. The function of HT2 in CO2 signalling pathway will be discussed.
