Integration of local and systemic signaling pathways for plant N responses

Nitrogen (N) is an essential macronutrient and a signal that has profound impacts on plant growth and development. In order to cope with changing N regimes in the soil, plants have developed complex regulatory mechanisms that involve short-range and long-range signaling pathways. These pathways act at the cellular and whole plant scale to coordinate plant N metabolism, growth and development according to external and internal N status. Although molecular components of local and systemic N signaling have been identified and characterized, an integrated view of how plants coordinate and organize the N response is still lacking. In this review, we discuss recent advances toward understanding the mechanisms of local and systemic N responses and provide an integrated model for how these responses are orchestrated.

► Nitrate transporter NRT1.1 is a nitrate transceptor. ► Nitrate treatments produce changes in gene expression at 12 min or earlier after treatment. ► Lateral root cap, pericycle and stele are the most nitrate-responsive cell types in roots. ► The systemic regulation of NRT2.1 depends on histone modification by HNI1-9/AtIWS1. ► The long-distance N signaling in roots is mediated by nitrate and cytokinins.