Miller Lab
ROS metabolism and signalling in the plant stress response
Research projects
Heat stress response in pollen.
Reproductive development in flowering plants is highly sensitive to temperature stress, with even a single hot day or cold night sometimes being fatal. In many plants, pollen development, and fertilization are often the most stress-sensitive compared to all other plant tissues. With the expected rise in global warming, and with human food supply largely dependent on seeds, our study of pollen thermotolerance is aimed at finding ways to improve plant's reproductive success.
Studying an apx2 mutant with increased pollen thermotolerance, which produces more seeds than the wild type under high temperatures, we identified several potential pollen-specific heat-stress mechanisms. We also use flow cytometry as a tool to evaluate pollen viability and other physiological aspects, as well as pollen cell biology.
Effect of heat stress on seed production and silique length in control (WT), apx1, apx2. (From Suzuki et al. J. Exp. Bot 2013, 64:253-63.
ROS-mediated rapid systemic responses to stress.
Long distance cellular signaling (i.e., systemic signaling) pathways enable multicellular organisms to prepare their tissues and cells for an upcoming challenge that may only have initially been sensed by a few local cells (6-10). They are induced in plants in response to different stimuli including mechanical injury, pathogen infection, or abiotic stresses, and enable the plant to achieve a higher level of tolerance by activating acclimation mechanisms that improve the overall survival and yield under stress. Systemic acquired acclimation (SAA), triggered by abiotic stress stimuli such as high light, temperatures, and osmotic stresses. In Arabidopsis, the development of SAA is mediated by a ROS signal that rapidly propagates in a cell-to-cell manner, which is dependent on the activity of the NADPH oxidase, respiratory burst oxidase homolog D (RbohD).
Recently we identified novel ROS-responsive regulatory components that are being tested for mediating both local responses to stress and SAA.
Rapid induction of Luciferase reporter gene
controlled by Zat12 promoter in locally wounded and systemic (distal non-wounded) leaves
Roles of the cAPXs in the plant's development and stress response.
The cytosolic (c)APXs, APX1,2 and 6, although sharing a high degree of similarity, are distinct in their regulation and their function in development and stress responses.This study combines several projects aiming at understanding how the three cAPXs by regulating ROS and redox signaling impact key developmental and stress-related processes.
Current projects:
1. Role of APX6 in seed development and leaf senescence
2. Impact of cAPX on acclimation to abiotic stresses such as drought tolerance, salinity and heat.
3. Involvement of cAPXs in mediating rapid long distance cell-to -cell communication (i.e. systemic signaling) in response to high light intensity and heat stress.