Plants respond to a reduction in the red/far-red ratio (R:FR) of light, caused by the proximity of other plants, by initiating morphological changes that improve light capture. In Arabidopsis, this response (shade avoidance syndrome, SAS) is controlled by phytochromes (particularly phyB), and is dependent on the TAA1 pathway of auxin biosynthesis. However, when grown in real canopies, we found ...