Spatiotemporal auxin distribution in Arabidopsis tissues is regulated by anabolic and catabolic reactions under long-term ammonium stress

BACKGROUND: The plant hormone auxin is a major coordinator of plant growth and development in response to diverse environmental signals, including nutritional conditions. Sole ammonium (NH(4)(+)) nutrition is one of the unique growth-suppressing conditions for plants. Therefore, the quest to understand NH(4)(+)-mediated developmental defects led us to analyze auxin metabolism. RESULTS: Indole-3-acetic acid (IAA), the most predominant natural auxin, accumulates in the leaves and roots of mature Arabidopsis thaliana plants grown on NH(4)(+), but not in the root tips. We found changes at the expressional level in reactions leading to IAA biosynthesis and deactivation in different tissues. Finally, NH(4)(+) nutrition would facilitate the formation of inactive oxidized IAA as the final product. CONCLUSIONS: NH(4)(+)-mediated accelerated auxin turnover rates implicate transient and local IAA peaks. A noticeable auxin pattern in tissues correlates with the developmental adaptations of the short and highly branched root system of NH(4)(+)-grown plants. Therefore, the spatiotemporal distribution of auxin might be a root-shaping signal specific to adjust to NH(4)(+)-stress conditions. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12870-021-03385-9.