Abstract
The phytohormone abscisic acid (ABA) regulates physiologically important developmental processes and stress responses. Previously, we reported on Arabidopsis L. Heynh. ahg mutants, which are hypersensitive to ABA during germination and early seedling growth. Among them, we found that AHG1 and AHG3 are identical to At5g51760 and AtPP2CA, respectively, which encode protein phosphatase 2Cs (PP2C). We demonstrated physiologically AHG1 and AHG3 function as negative regulators of the ABA signaling during seed germination. Multiple PP2Cs are known to be negative regulators of the ABA signaling, but the precise molecular function of these proteins are not elucidated because of luck of information about physiological substrates. In the past, some PP2C-interacting proteins have been isolated by mainly yeast two-hybrid system. We are trying to identify the targets of AHG1 and AHG3/AtPP2CA by some proteomic approaches such as the two-dimensional electrophoresis and the pull down assay. We will show the progress of these attempts.
