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Abstract

The coordination of cellular behaviour within a tissue or organ requires intercellular communication that is poorly understood in plants. Signaling by the receptor-like kinase STRUBBELIG (SUB) is repeatedly required during Arabidopsis development in processes such as floral morphogenesis and ovule development1. At the cellular level SUB regulates cell shape and the cell division plane in a specific cell layer of floral meristems. In addition, SUB, also known as SCRAMBLED (SCM), affects root hair patterning2. Interestingly, we have previously shown that phosphotransfer activity of SUB is not required in vivo indicating that SUB is a so-called atypical or dead receptor-like kinase1. As little is known about signaling by atypical receptor kinases in plants and in animals SUB signal transduction also serves as an excellent model to investigate the mechanistic basis of signal transduction by this class of unusual receptor kinases. Here we provide evidence that SUB acts in a non-cell-autonomous fashion and mediates cell morphogenesis and cell fate across clonally distinct cell layers in a radial inside-out signaling process in floral primordia, young ovules and root meristems. Using a combination of forward genetics and a systematic comparison of whole genome transcriptome profiles we have also identified three genes, DETORQUEO (DOQ), QUIRKY (QKY), and ZERZAUST (ZET), that are involved in SUB-dependent processes. The data shed light on the mechanisms that depend on signaling through the atypical receptor-like kinase SUB.