Abiotic and biotic stress differentially stimulate as-1 element activity in Arabidopsis

As-1-type cis-elements enhance the expression of putative plant protective genes in response to xenobiotic chemical stress. Here we investigate the effect of developmental changes on as-1-dependent transcription activities under basal and stimulus-induction conditions. We show that different xenobiotic stress cues give rise to distinct, differential patterns of as-1 activity in planta, which are further effected by developmental control. Moreover, transcription through as-1 is potentiated by infection with a virulent strain of Pseudomonas syringae, in line with recent genetic evidence indicating a role for this element and its cognate TGA transcription factors in host-defense gene responses. Our results here are consistent with the notion that inputs from both developmental and stimulus induction pathways define the complex spatial and temporal expression pattern of as-1 activity in plants.