Transcriptomic analysis reveals light quality response and systemic nutrient allocation under monochromatic light environments in Nicotiana tabacum

Light quality plays a crucial role in plant growth and development. Nevertheless, mechanistic insights regarding the effects of monochromatic red light and monochromatic blue light on the development of tobacco seedlings remain limited. This study aims to elucidate how monochromatic red and blue light specifically affect the growth of tobacco seedlings, with a focus on systemic nutrient allocation from roots. By analyzing morphological, physiological and transcriptomic changes in both shoots and roots, we aim to fill the gaps in our understanding of the interaction between light quality and nutrient absorption mechanisms. Physiological results indicated that red light promoted seedling growth and enhanced nitrogen (N)and potassium (K) uptake, whereas blue light exerted the opposite effect by inhibiting growth and reducing nutrient uptake. Transcriptome analysis revealed that genes related to N uptake (e.g., NRT1.1 was induced by red light and suppressed by blue light), N assimilation and K uptake were significantly regulated by monochromatic light in roots. Furthermore, various transcription factors (TFs) involved in phytohormone signal transduction were significantly regulated by blue and red light. These findings suggest that red and blue light may modulate phytohormone metabolism through TF-mediated pathways in tobacco roots. Overall, this study provides valuable insights into the effects of light quality on plant growth and underscores the importance of elucidating light-mediated mechanisms for improving crop yield and quality.