Elucidating the molecular basis of sugar-mediated PTMs of NLP7 in regulating carbon-nitrogen metabolic coupling in plants

Nitrogen is an indispensable nutrient for plant growth, essential for synthesizing proteins, nucleic acids, and chlorophyll. It is often the rate-limiting macronutrient in agricultural practices. Applications of nitrogen fertilizers effectively boost crop growth and yield. However, overuse of nitrogen fertilizers raises farming costs and poses a great threat to the environment, causing issues like soil acidification, compaction, and eutrophication. Improving nitrogen use efficiency (NUE) is vital for sustainable agriculture. Nitrate, the primary form of nitrogen in soil, not only serves as a macronutrient but also acts as a signaling molecule that regulates nitrogen uptake, metabolism, growth, and many developmental processes. Thus, elucidating the regulatory mechanisms of nitrate signaling is critical for improving NUE in crops and paves the way for greener farming practices.

Nitrogen (N) and carbon (C) metabolism are tightly coupled during plant growth and development, and their balance is critical for crop productivity and environmental adaptation. Sugar produced by photosynthesis in the aerial parts of plants provides energy to the roots for assimilating and metabolizing nitrogen, which is often the limiting factor for building and supporting the photosynthetic apparatus. It has been proposed that the interactions between sugar and nitrate signaling pathways contribute to CN balance in plants by coupling carbon-nitrogen metabolism, but the molecular underpinnings of such interactions are not fully understood. In this project, my collaborator and I will analyse how conserved energy and sugar signaling pathways mediated by TOR, SnRK1, and SPY modulate the activity of key nitrate sensor NLP7 to facilitate the metabolic coupling of sugar and nitrogen. Our studies will not only shed light on the regulatory mechanisms underlying nitrate signaling, CN metabolic coupling, and CN homeostasis in plants, but could also provide guidance and genetic resources for improving crop NUE in diverse growth conditions.