Avoiding the shadow: how plants perceive neighbors and reshape the crop light environment

Plants in typical agricultural stands inevitably experience mutual shading. As the canopy develops, neighbor cues progressively reduce the activity of photo-sensory receptors, de-repressing shade-avoidance responses (SARs) that drastically reshape plant architecture. This review synthesizes recent molecular advances in understanding the signaling mechanisms underlying SARs. We specifically delve into the photoreceptors, the complex transcriptional networks they regulate, and the signaling molecules that operate downstream or in parallel. A central focus is the dynamic features of the SAR network, which drive signal amplification initiated by brief interruptions of shade from direct sunlight, and the epigenetic memory that allows plants to recall and respond to previous shade events. Recent progress also reveals key similarities and differences in SAR mechanisms between Arabidopsis and major crop species. Ultimately, we consolidate information demonstrating that SARs can be either beneficial or detrimental to crop productivity, depending on the genetic material, environmental context, and specific management practices.