Nitrate signaling promotes plant growth by upregulating gibberellin biosynthesis and destabilization of DELLA proteins

Nitrate, one of the main nitrogen (N) sources for crops, acts as a nutrient and key signaling molecule coordinating gene expression, metabolism, and various growth processes throughout the plant life cycle. It is widely accepted that nitrate-triggered developmental programs cooperate with hormone synthesis and transport to finely adapt plant architecture to N availability. Here, we report that nitrate, acting through its signaling pathway, promotes growth in Arabidopsis and wheat, in part by modulating the accumulation of gibberellin (GA)-regulated DELLA growth repressors. We show that nitrate reduces the abundance of DELLAs by increasing GA contents through activation of GA metabolism gene expression. Consistently, the growth restraint conferred by nitrate deficiency is partially rescued in global-DELLA mutant that lacks all DELLAs. At the cellular level, we show that nitrate enhances both cell proliferation and elongation in a DELLA-dependent and -independent manner, respectively. Our findings establish a connection between nitrate and GA signaling pathways that allow plants to adapt their growth to nitrate availability. •Nitrate promotes plant growth in a DELLA-dependent manner•Nitrate promotes root elongation via DELLA-dependent action on cell proliferation•Nitrate signaling modulates DELLA protein accumulation•Nitrate supply enhances GA synthesis in Arabidopsis and wheat Nitrate is one of the main nitrogen sources for plants. Camut et al. demonstrate genetically that nitrate supply promotes plant growth through the activation of gibberellin biosynthesis, which in turn reduces the accumulation of growth-repressing DELLA proteins.