Molecular Mechanisms of Light Signalling in Root Architecture: From Photoreception to Developmental Regulation

As the primary energy source for photosynthesis, light also serves as a critical environmental cue regulating developmental plasticity through photomorphogenesis. While extensive research has characterized light-mediated shoot development, including hypocotyl de-etiolation, cotyledon expansion and chloroplast biogenesis, emerging evidence demonstrates that light signals also profoundly influence the root. Phenotypic analyses of photoreceptor mutants have revealed that roots, like above-ground tissues, perceive and respond to light signals through sophisticated signalling networks. This review synthesizes current understanding of core light signalling cascades and the systemic mechanisms facilitating shoot-to-root signal transmission. We highlight recent advances in understanding how light quality and intensity modulate root development through hormonal crosstalk and transcriptional reprogramming. By integrating molecular mechanisms with agronomic applications, we further provide a detailed summary of the application of plant photobiology. It suggests practical strategies for optimizing root development through light-mediated control.