Ammonium nutrition interacts with iron homeostasis in Brachypodium distachyon

12 Pags.- 7 Figs. © The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Experimental Biology. This pathway includes Open Access publishing (CC By License).Most plant species develop stress symptoms when exposed to high ammonium (NH4+) concentrations. The root is the first organ in contact with high NH4+ and therefore the first barrier to cope with ammonium stress. In this work, we focused on root adaptation to ammonium nutrition in the model plant Brachypodium distachyon. Proteome analysis revealed changes associated with primary metabolism, cell wall remodelling, and redox homeostasis. In addition, it showed a strong induction of proteins related to methionine (Met) metabolism and phytosiderophore (PS) synthesis in ammonium-fed plants. In agreement with this, we show how ammonium nutrition impacts Met/S-adenosyl-Met and PS metabolic pathways together with increasing root iron content. Nevertheless, ammonium-fed plants displayed higher sensitivity to iron deficiency, suggesting that ammonium nutrition triggers impaired iron utilization and root to shoot transport, which entailed an induction in iron-related responses. Overall, this work demonstrates the importance of iron homeostasis during ammonium nutrition and paves a new way to better understand and improve ammonium use efficiency and tolerance.This research was funded/supported by the Basque Government (IT932-16) and the Spanish Ministry of Economy and Competitiveness (BIO2017-84035-R and PID2020-113385RB-I00 co-funded by FEDER). MP held a doctoral scholarship (Conv. 672) associated with COLCIENCIAS (Department of Science, Technology and Innovation of Colombia) and the Department of Magdalena. LU holds a PhD grant from the Basque Government and AJMP from the Spanish Ministry of Economy and Competitiveness.Peer reviewe