ABA and Ethylene
Song, Charlotte , Kwak, June .
MAP kinases in ROS-mediated ABA Signaling.
Drought causes severe damage and reduced yields for crops. The phytohormone, abscisic acid (ABA), plays an essential role in protection of plants from a variety of environmental stresses such as drought, salt, and cold. Guard cells are responsible for controlling CO2 uptake and water loss by regulating the size of stomatal pores. During drought stress, a rapid response of a plant is to close stomatal pores. This process is mediated by ABA. In stomatal guard cells, reactive oxygen species (ROS) have been suggested to function in ABA signaling. Despite extensive studies, molecular components working downstream of ROS in ABA signaling remain to be elucidated. In order to identify and characterize MAPK cascades mediating guard cell ABA/ROS signaling, we identified two MAPK genes, GCMAPK3 and GCMAPK4, that are preferentially and highly expressed in guard cells. To provide direct genetic evidence, RNAi-based gene silencing plant lines were generated in which both genes are silenced. In parallel, Arabidopsis single and double mutants carrying deleterious point mutations in these genes were generated. Interestingly, ABA-induced stomatal closure was strongly impaired in the RNAi lines in which both GCMAPK3 and GCMAPK4 transcripts were significantly silenced. Consistent with this result, the Arabidopsis mutants carrying point mutations in both genes showed a strong ABA-insensitive response in stomatal movement assays. Together, these results provide genetic evidence that GCMAPK3 and GCMAPK4 function in guard cell ABA signaling, and there is functional redundancy in these genes. Currently, we are trying to further determine functional contribution of these genes to the ABA/ROS signaling
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1 - University of Maryland, Cell Biology and Molecular Genetics, 2127 H. J. Patterson Hall, College Park, MD, 20742, USA
2 - University of Maryland, Cell Biology and Molecular Genetics
reactive oxygen species
Presentation Type: ASPB Minisymposium
Location: Continental B/Hilton
Date: Wednesday, July 11th, 2007
Time: 9:20 AM