The transcriptome of Arabidopsis thaliana during systemic acquired resistance

Infected plants undergo transcriptional reprogramming during initiation of both local defence and systemic acquired resistance (SAR). We monitored gen e-expression changes in Arabidopsis thaliana under 14 different SAR-inducin g or SAR-repressing conditions using a DNA microarray representing approxim ately 25-30% of all A. thaliana genes. We derived groups of genes with comm on regulation patterns, or regulons. The regulon containing PR-1, a reliabl e marker gene for SAR in A. thaliana, contains known PR genes and novel gen es likely to function during SAR and disease resistance. We identified a co mmon promoter element in genes of this regulon that binds members of a plan t-specific transcription factor family. Our results extend expression profi ling to definition of regulatory networks and gene discovery in plants.