Genetic screens to identify ROS signal transducers in Arabidopsis thaliana

In order to survive in constantly changing environments plants developed efficient systems that allow adaptation towards multiple stress conditions. The interactions with environment are associated with tailored expression of nuclear genes that ultimately lead to changes in cellular metabolism and at the whole organism level. Previously, we identified photorespiratory hydrogen peroxide as a signaling molecule that provokes changes in expression of over 700 genes (H2O2-induced genes; HIGs). To gain insight into the oxidative stress-related functions of these HIGs we took a reverse genetic approach and screened the corresponding T-DNA insertion mutants for ~ 200 of these genes for altered oxidative stress tolerance. A loss-of-function mutation in SUGAR TRANSPORT PROTEIN 13 (stp13-1) which encodes for a high affinity H+/D-hexose symporter, had a significant impact on oxidative stress resistance. Under stress conditions, plants lacking STP13 exhibited early decrease in PSII maximum efficiency that was associated with enhanced survival. Overexpression of STP13 led to opposite phenotypes and resulted in early progress of chlorosis. The analysis of loss- and gain-of-function STP13 transgenics indicated an important role for sugar availability in the oxidative stress response. Further experiments provided a link between energy signaling and plant stress responses with a major role of SNF1-RELATED PROTEIN KINASE 1.