Identification of a novel cis-acting element conferring sulfur deficiency response in Arabidopsis roots

Abstract

SULTR1;1 high-affinity sulfate transporter is highly regulated in the epidermis and cortex of Arabidopsis roots responding to sulfur deficiency (-S). We identified a novel cis-acting element involved in the -S-inducible expression of sulfur-responsive genes in Arabidopsis. The promoter region of SULTR1;1 was dissected for deletion and gain-of-function analysis using luciferase (LUC) reporter gene in transgenic Arabidopsis. The 16-bp sulfur-responsive element (SURE) from -2777 to -2762 of SULTR1;1 promoter was sufficient and necessary for the -S-responsive expression, which was reversed when supplied with cysteine and glutathione (GSH). The SURE sequence contained an auxin response factor (ARF) binding sequence (GAGACA). However, SURE was not responsive to naphthalene acetic acid, indicating its specific function in the sulfur response. The base substitution analysis indicated the significance of a 5-bp sequence (GAGAC) within the conserved ARF binding site as a core element for the -S response. Microarray analysis of early -S response in Arabidopsis roots indicated the presence of SURE core sequences in the promoter regions of -S-inducible genes on a full genome GeneChip array. It is suggested that SURE core sequences may commonly regulate the expression of a gene set required for adaptation to the -S environment.