Several mechanisms have been proposed to explain NH4+ toxicity. However, the core information about the biochemical regulation of plants in response to NH4+ toxicity is still lacking. In this study, the tissue NH4+ concentration is an important factor contributing to variations in plant growth even under nitrate nutrition and NH4+ tolerance under ammonium nutrition. Furthermore, NH4+ led to the reprogramming of the transcriptional profile, as genes related to trehalose-6-phosphate and zeatin biosynthesis were downregulated, whereas genes related to nitrogen metabolism, camalexin, stilbenoid an...
