DARK SIDE: Plants use different growth mechanisms in dark and light conditions, called skotomorphogenesis and photomorphogenesis, respectively. A new study suggests pectin fragments in the cell wall signal other cells to maintain skotomorphogenesis in darkness. From these results, a model has emerged in which light somehow interrupts this pectin-based signaling so that photomorphogenesis can commence.© JULIA MOORE
The paper
S.A. Sinclair et al., “Etiolated seedling development requires repression of photomorphogenesis by a small cell-wall-derived dark signal,” Curr Biol, 27:3403-18.e7, 2017.
Plants don’t always need sunlight to grow. Through a process called skotomorphogenesis, seedlings germinated in the dark—say, too far under the soil surface—will stretch out into long, pale shoots, searching for light. Think of the spindly bean sprouts you might buy at the store, offers Ute Krämer, a plant physiologist at Ruhr-Universität Bochum in Germany. It’s an energy-saving tactic to get plants to the light. Once they do get there, they switch irreversibly to light-driven growth called photomorphogenesis—spreading out their roots and developing their leaves.
Krämer says that while the cellular components governing photomorphogenesis have been understood for decades, the cell-to-cell signaling ...
