Seeds and Seedlings: How Arabidopsis Thaliana Integrates Light Signalling in Its Earliest Life Stages

The ability to detect and respond to light signals is essential for a plant to maximise its fitness. These signals, including photoperiod, regulate key aspects of a plant's development, from the timing of seed germination through to the floral transition. How the photoperiod regulates hypocotyl elongation and the floral transition is now well understood at the molecular level. In contrast, how light and circadian signals are perceived and integrated in seeds is less clear. In this review, we highlight the latest insights into how light, photoperiod, and circadian signalling regulate development in seedlings and seeds. We also discuss how even though these two developmental stages employ many of the same components, re-wiring of the regulatory network that these components operate within enables the distinct developmental demands of germinating and seedling growth in responding to the environment cues. Finally, we highlight key knowledge gaps and future directions of research in how seedlings and seeds sense integrate light and circadian signals during development.