MAP kinases MPK9 and MPK12 are preferentially expressed in guard cells and positively regulate ROS-mediated ABA signaling

• DOI: 10.1073/pnas.0907205106
• Publication Date: 2009-11-13T03:17:50Z
• Authors: Fabien Jammes; Charlotte Song; Dongjin Shin; Shintaro Munemasa; Kouji Takeda; Dan Gu; Daeshik Cho; Sangmee Lee; Roberta Giordo; Somrudee Sritubtim; Nathalie Leonhardt; Brian E. Ellis; Yoshiyuki Murata; June M. Kwak
• Keywords: 0303 health sciences; Microscopy, Confocal; Arabidopsis Proteins; Blotting, Western; Arabidopsis; 03 medical and health sciences; Mutation; Plant Stomata; Immunoprecipitation; Calcium; RNA Interference; Mitogen-Activated Protein Kinases; Reactive Oxygen Species; Abscisic Acid; Signal Transduction

Reactive oxygen species (ROS) mediate abscisic acid (ABA) signaling in guard cells. To dissect cell ABA-ROS genetically, a type-specific functional genomics approach was used to identify 2 MAPK genes, MPK9 and MPK12, which are preferentially highly expressed provide genetic evidence for their function, Arabidopsis single double TILLING mutants that carry deleterious point mutations these genes were isolated. RNAi-based gene-silencing plant lines, both silenced simultaneously, generated also. Mutants carrying mutation only 1 of did not show any altered phenotype, indicating redundancy genes. ABA-induced stomatal closure strongly impaired independent RNAi lines MPK12 transcripts significantly silenced. Consistent with this result, mpk9-1/12-1 showed an enhanced transpirational water loss ABA- H(2)O(2)-insensitive response. Furthermore, ABA calcium failed activate anion channels cells mpk9-1/12-1, MPKs act upstream signaling. An MPK12-YFP fusion construct rescued the ABA-insensitive response phenotype demonstrating caused by mutations. The protein is localized cytosol nucleus, H(2)O(2) treatments enhance kinase activity MPK12. Together, results function downstream ROS regulate positively.