Focus

The plant response to shade

This work addresses the plant response to conditions of shade. Plants grown under canopies perceive the reduction in the ratio of red (R) to far-red (FR)
light as a warning of competition, and they enhance elongation
growth in an attempt to overgrow their neighbors. Here, Dr. Ida Ruberti's
group report that the same low R/FR signal that induces hypocotyl elongation also triggers a rapid arrest of leaf primordium growth, ensuring that plant resources are redirected into extension growth. We find that the growth arrest induced by low R/FR depends on auxin-induced cytokinin breakdown in developing primordia. On the whole, therefore, these findings identify a previously unrecognized regulatory circuit underlying the plant response to shade.
Canopy shade causes a rapid and transient arrest in leaf development through auxin-induced cytokinin oxidase activity. Carabelli M, Possenti M, Sessa G, Ciolfi A, Sassi M, Morelli G, Ruberti I. Genes Dev. 2007 vol. 21:1863-8.