Proximal–distal patterns of transcription factor gene expression during Arabidopsis root development

The expression pattern of genes can identify the cells in which the respective proteins are active during development. As a step towards defining the genetic network that controls the development of roots, a high-throughput method of whole-mount in situ hybridization has been developed that does not require expensive equipment and allows the definition of the expression patterns of 137 transcription factor genes in young developing roots. Of the 137 transcription factors, 81.8% were expressed in the root while 18.2% showed no detectable expression. In all three proximal distal zones (meristem, elongation, and differentiation) of the root, 52.6% were expressed whereas 21.2% were expressed in only two zones. Eight percent of the genes were expressed in a single proximal distal zone. Cell-specific gene expression patterns were also detected. This rapid approach identified potential key regulators of cell differentiation and provides important spatial information for the expression patterns of a large number of transcriptional regulators that function during root development.