Genome-wide analysis of AAAG and ACGT cis-elements in Arabidopsis thaliana reveals their involvement with genes downregulated under jasmonic acid response in an orientation independent manner

Abstract

Cis-regulatory elements are regions of noncoding DNA that regulate the transcription of neighboring genes. The study of cis-element architecture that functions in transcription regulation are essential. AAAG and ACGT are a class of cis-regulatory elements, known to interact with Dof and bZIP transcription factors respectively, and are known to regulate the expression of auxin response, gibberellin response, floral development, light response, seed storage proteins genes, biotic and abiotic stress genes in plants. Analysis of the frequency of occurrence of AAAG and ACGT motifs from varying spacer lengths (0-30 base pair) between these 2 motifs in both possible orientations-AAAG (N) ACGT and ACGT (N) AAAG, in the promoters and genome of Arabidopsis thaliana which indicated preferred orientation of AAAG (N) ACGT over ACGT (N) AAAG across the genome and in promoters. Further, microarray analysis revealed the involvement of these motifs in the genes downregulated under jasmonic acid response in an orientation-independent manner. These results were further confirmed by the transient expression studies with promoter-reporter cassettes carrying AAAG and ACGT motifs in both orientations. Furthermore, cluster analysis on genes with AAAG (N) ACGT and ACGT (N) AAAG motifs orientations revealed clusters of genes to be involved in ABA signaling, transcriptional regulation, DNA binding, and metal ion binding. These findings can be utilized in designing synthetic promoters for the development of stress-tolerant transgenic plants and also provides an insight into the roles of these motifs in transcriptional regulation.

Keywords: cis-regulatory elements; Dof; bZIP; promoter; transcription factor.