The sun doesn't shine equally on everyone

Abstract

For plants, light is not only a basic energ y staple but also a source ofcrucial environme ntal clues. Plant metabolic and developmentalresponses are exquisitely attuned to variations in light quantity,quality, direction and periodicity. Changes in light quantity anddirection unleash a full range of adaptive behaviours, fromreshuffling of photosyn thetic complexes to the reorganization ofthe cellular outfit of light harvesting organs and tropisms. Seasonaldaylength variations synchronize reproductive responses, and diellight cycles impinge on most, if not every, physiological processes.Finally, changes in light wavelength composition allow plants togauge their exposure to direct sunlight and modulate processes likegermination or differential growth to avoid shading by neighbours.Plants sense light conditions through a series of photoreceptors thatcover the range of photosynthetically useful, and potentiallydamaging, radiation. An enormous amount of work has beenamassed throughout several decades on the characterization of thesesensors. However, whether every cell in a plant perceives andresponds to light in a similar way, and how different inputs cometogether to mount coordinated responses in the organism as a wholeare questions that have only recently been tackled. In this issue ofNew Phytologist, Kirchenbauer et al.; (pp. 584-598) provide newevidence indicating that, ind eed, different tissues or cell typespreferentially coordinate certain responses to changes in lightquantity and quality.