Throughout 1994 remarkable progress was made with molecular and genetic studies on signal transduction pathways of photomorphogenesis, the lightdependent development of plants. Analysis of Arabidopsis DET and COP genes suggests that they are involved in suppression of photomorphogenic development in the dark and that this is then reversed by light. Studies with COP1 indicate that this is achieved by redistribution of COP1 from the nucleus, in the dark, to the cytosol in the light(1). Overexpression of COP1 in the light, however, (...) was able to partially suppress photomorphogenic development, confirming its role as a light‐inactivatable repressor(2). Evidence also suggests that some of the COP gene products may interact directly to form a large complex(3). (shrink)