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.

BPMP Univ Montpellier CNRS INRAE Montpellier SupAgro Montpellier France

Institut de Biologie Moléculaire des Plantes CNRS University of Strasbourg 67084 Strasbourg France

Instituto de Biología Molecular y Celular de Plantas CSIC UPV 46022 Valencia Spain

Plant Science Department Rothamsted Research Harpenden AL5 2JQ UK

Plant Science Department Rothamsted Research Harpenden AL5 2JQ UK; Laboratory of Growth Regulators Institute of Experimental Botany and Palacky University 78371 Olomouc Czech Republic

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