Transcription profiling by array of serrate-1 mutant Arabidopsis seedlings

microRNAs function as sequence-specific guides to regulate genes by post-transcriptional gene silencing. Many miRNAs are involved in the control plant development by regulating the accumulation of transcripts encoding transcription factors. This causes pleiotropic developmental phenotypes of mutants defective in miRNA accumulation, such as dcl1, hen1, hyl1 and ago1. The serrate-1 (se-1) mutant of Arabidopsis also exhibits a highly pleiotropic phenotype which overlaps with phenotypes of mutants defective in miRNA accumulation. It has been proposed that SE functions specifically in miRNA-mediated repression of the leaf polarity genes PHABULOSA and PHAVOLUTA. Microarray analysis of transcript levels in se-1 compared to wild-type however revealed upregulation of many genes known to be targets of miRNA regulation. We show that SE is a general regulator of miRNA levels probably controlling processing of pri-miRNA to miRNA.