Making the most of canopy light: shade avoidance under a fluctuating spectrum and irradiance.

In the field, plants face constantly changing light conditions caused by both atmospheric effects and neighbouring vegetation. This interplay creates a complex, fluctuating light environment within plant canopies. Shade-intolerant species rely on light cues from competitors to trigger shade avoidance responses, ensuring access to light for photosynthesis. While research often uses controlled growth chambers with steady light to study shade avoidance responses, the influence of light fluctuations in real-world settings remains unclear. This review examines the dynamic light environments found in woodlands, grasslands, and crops. We explore how plants respond to some fluctuations but not others, analyse the potential reasons for these differences, and discuss the possible molecular mechanisms regulating this sensitivity. We propose that studying shade avoidance responses under fluctuating light conditions offers a valuable tool to explore the intricate regulatory network behind them.