Natural variation in phytochrome signaling.

The phytochromes, photoreceptors sensitive to red and far-red light, are critical for sensing foliage shade, canopy breaks, and neighbor proximity. A combination of molecular genetic, evolutionary, and ecological techniques are being used to understand how phytochromes function in the natural environment. We discuss studies on the adaptive value of phytochrome mediated plasticity, as well as therole that variation in phytochrome expression and function might play in allowing plants to adapt to unique light environments. Continued study of phytochrome signaling variation may reveal how natural selection acts at the molecular level.