Differential submergence tolerance between juvenile and adult Arabidopsis plants involves the ANAC017 transcription factor.

Plants need to attune their stress responses to the ongoing developmental programs to maximize their efficacy. For instance, successful submergence adaptation is often associated with a delicate balance between saving resources and their expenditure to activate measures that allow stress avoidance or attenuation. We observed a significant decrease in submergence tolerance associated with aging in Arabidopsis thaliana, with a critical step between two and three weeks of post-germination development. This sensitization to flooding was concomitant with the transition from juvenility to adulthood. Transcriptomic analyses indicated that a group of genes related to ABA and oxidative stress response was more highly expressed in juvenile plants than in adult ones. These genes are induced by the endomembrane tethered transcription factor ANAC017 that was in turn activated by submergence-associated oxidative stress. A combination of molecular, biochemical and genetic analyses showed that these genes are located in genomic regions that move towards a heterochromatic state with adulthood, as marked by lysine 4 trimethylation of histone H3. We concluded that, while the mechanism of flooding stress perception and signal transduction were unaltered between juvenile and adult phases, the sensitivity that these mechanisms set into action is integrated, via epigenetic regulation, into the developmental programme of the plant. Supporting Information Fig. S1 SPL family gene expression in juvenile or adult plant. Fig. S2. Regulation of the ARuS genes in response to external perturbations. Fig. S3. Histochemical assessment of ROS production in juvenile and adult plants. Fig. S4 Profile of expression of ANAC013 (red line), 16 (blue), and 17 (green) across ten stages Arabidopsis development. Fig. S5 Expression of three submergence-responsive genes (CYP71E, GST25 and AOX1D) in the wild type and the anac017-1 mutant. Fig. S6 Phenotypical and molecular evaluation of pUBQ10:RFP-ANAC017-GFP transgenic plants. Fig. S7 Full immunoblot images related to Fig. 7d. Fig. S8 DNA methylation at the UBQ10 and SPL9 promoters.