Light signaling: back to space.

Recent work has increased our understanding of the molecular and cellular mechanisms of the phytochrome family of photoreceptors in controlling plant photomorphogenesis. However, the importance of long-distance communication in controlling light responses has received relatively little attention and is poorly understood. In this article, by taking a closer look at old and new experiments that extend the analysis of light signaling beyond the limits of the plant cell, we offer to look at the field in a new light. Furthermore, we discuss how intercellular and inter-organ communication might integrate with the transcriptional networks controlling light-regulated responses in plants, a novel view that might help to re-assess the parameters by which we screen for photomorphogenic mutants in the future.