12/27/2025
🚜Nitrogen (N) is essential for plant growth, but excessive fertilizer use decreases nitrogen use efficiency (NUE) and raises environmental concerns.
🚿This study investigated the effect of exogenous abscisic acid (ABA; 50 μM) application on rapeseed (Brassica napus L.) plants under hydroponic conditions with high (7.5 mM NO3−) and low (0.25 mM NO3−) nitrate.
📉N deficiency significantly reduced growth, chlorophyll, gas exchange, and stomatal size (length and width). Exogenous ABA application under low N conditions increased the N content (23.1%) and the activities of nitrate reductase (NR; 15.7%), glutamine synthetase (GS; 30.3%), and GS/glutamate synthase (GOGAT; 19.3%).
📊It also enhanced activities of antioxidant enzymes: superoxide dismutase (SOD; 18.3%), peroxidase (POD; 30.2%), ascorbate peroxidase (APX; 39%), catalase (CAT; 16.3%), and endogenous hormones: ABA (35.3%), salicylic acid (SA; 20.5%), indole acetic acid (IAA; 49.8%), and jasmonic acid (JA; 90.3%) compared to untreated low N conditions.
🔬Histochemical staining (NBT and DAB) confirmed that ABA alleviated oxidative stress under N deficiency. Transcriptomic analysis identified differentially expressed genes related to photosynthesis, antioxidant defense, N metabolism, and ABA signaling (PYL/PYR/RCAR receptors, PP2C phosphatases, SnRK2 kinases). Transcription factors from bZIP, MYB, and AP2/ERF families were significantly regulated.
👉These results highlight the mechanisms of ABA-mediated N stress mitigation and provide a basis for improving NUE in rapeseed through genetic approaches such as overexpression CRISPR/Cas9, supporting sustainable agriculture.
Read more https://bit.ly/4iuhjX2
