Differential analysis of oat leaf metabolism under salt and alkali stress

To compare the metabolism of oat under salt and alkali stress, we analyzed the main differential metabolites and the metabolic pathways under salt and alkali stress conditions using wide target metabolome and targeted metabolome assays. The results showed that lipid metabolites were the main differential metabolites in oat leaves under both salt and alkali stress conditions, whereas the differential metabolites between salt and alkali stress were organic acids. Enrichment analysis showed that the tricarboxylic acid cycle (TCA) cycle is the main pathway that responds to alkali stress, but not to salt stress. Organic acids in the TCA cycle detected using a targeted metabolome assay showed that citric, aconitic, succinic, fumaroid, malic, and oxaloacetic acids were higher under alkali stress than under salt stress. Among these, the content of aconitic acid under alkali stress was significantly higher than that of other organic acids in the TCA cycle. In conclusion, organic acid metabolism is the major difference between salt and alkali stress, and the TCA cycle is the main pathway of organic acid metabolism. To our knowledge, this is the first study to use a metabolomic approach to confirm that the TCA cycle is the main metabolic pathway of oat leaves that differentiates the response to alkali and salt stress. Aconitic acid plays a major role in the process of organic acid regulation in oat leaves in response to alkali stress, and the results may lay the foundation for the analysis of the differential mechanisms of oat response to salt and alkali stress.