Integrated Transcriptomic and Metabolomic Analyses Reveal Key Responses of Cotton to Salt Stress Post-Germination.

Salt stress is a major environmental constraint that severely limits cotton seed germination. However, the regulatory mechanisms governing salt stress responses during the post-germination stage remain largely unclear. Here, we employed an integrated transcriptomic and metabolomic approach to investigate salt-responsive mechanisms in the salt-tolerant cotton cultivar ST022-1056m5 (ST) following exposure to 150 mM NaCl. Our analysis identified 4368 differentially expressed genes (DEGs) and 441 differentially accumulated metabolites (DAMs) under salt stress conditions. Multi-omics integration revealed that alpha-linolenic acid and linoleic acid metabolic pathways were particularly responsive to salt stress. In the α-linolenic acid pathway, salt stress triggered substantial accumulation of jasmonic acid (JA) precursors and concurrent upregulation of key JA biosynthetic genes. Simultaneously, the linoleic acid metabolism pathway exhibited increased metabolite levels and enhanced the relative gene expression. These findings provide compelling evidence that alpha-linolenic acid and linoleic acid metabolism pathways collectively modulate post-germination salt stress responses in cotton, offering new insights into the molecular mechanisms underlying salt tolerance and presenting potential targets for breeding resilient cotton varieties.