Contents

23 March 2012
Vol 335, Issue 6075

About The Cover

Cover image expansion

COVER Spring sun lights up signaling pathways. In plants, the UVR8 protein senses ultraviolet-B (UV-B) wavelengths in sunlight, triggering changes in growth and development, including the production of a protective chemical sunscreen. Pyramids of tryptophan rings intrinsic to UVR8 create a built-in light switch; no separate chromophore is required. Understanding how plant growth varies with changes in sunlight becomes more important as we adapt to climate change. See page 1492. Photo: iStockphoto.com