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

Abstract

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 (NH4+) nutrition is one of the unique growth-suppressing conditions for plants. Therefore, the quest to understand NH4+-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 NH4+, 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, NH4+ nutrition would facilitate the formation of inactive oxidized IAA as the final product. Conclusions NH4+-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 NH4+-grown plants. Therefore, the spatiotemporal distribution of auxin might be a root-shaping signal specific to adjust to NH4+-stress conditions.

Ammonium/Nitrate Ratio Affects the Growth and Shikonin Accumulation in <em>Arnebia euchroma</em>

“…In the taproot grown in (NH4)2SO4, the nutrient and metabolic imbalance induced by ammonium was partially overcome by the increase of auxin level. Dziewit et al [55] studied the temporal and spatial distribution of auxin in Arabidopsis thaliana under long-term ammonium toxicity and found that auxin accumulated in leaves and roots, but not in root tips. The apparent auxin pattern in tissues is associated with the developmental adaptation of ammonium-growing plants with short branches and highly branched roots.…”

Colletotriauxins A–D, New Plant Growth Inhibitors from the Phytopathogenic Fungus Colletotrichum gloeosporioides

“…, growth inhibition at high concentrations and plant stimulation at low concentrations. This process is regulated by its biosynthesis, degradation, conjugation, and transport . IAA can also be formed from tryptophol by two subsequent oxidation steps .…”

“…This process is regulated by its biosynthesis, 4 degradation, 6 conjugation, 7 and transport. 8 IAA can also be formed from tryptophol by two subsequent oxidation steps. 4 Tryptophol glycosides, e.g., glucosides, galactosides, and arabinosides, often serve as a reservoir of IAA to keep the auxin balance in vascular plants.…”

The Integration of Metabolomics and Transcriptomics Provides New Insights for the Identification of Genes Key to Auxin Synthesis at Different Growth Stages of Maize

“…The compounds indole-3-acetic acid (IAA), 1H-indole-3-butanoic acid (IBA), 1-naphthalene-acetic acid (NAA), 2-naphthoxy-acetic acid (BNOA), 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-phenoxyacetic acid (4-CP), and 4-iodophenoxyacetic acid (4-iodo pyridine) are collectively termed auxins [ 4 ]. Indoleacetic acid was the first plant hormone to be discovered and is mainly distributed in actively growing tissues, such as stem meristems, leaf primordia, young leaves, developing fruit and seeds, and pollen grains [ 5 ]. Auxins promote the formation of lateral roots and adventitious roots, adjust flowering and sex differentiation, regulate fruit set and development, and control apical dominance [ 6 , 7 ].…”