Nitric Oxide Enhances Salt Tolerance in Ginger Seedlings Through Phytohormone Homeostasis and Starch and Sugar Metabolism.

Nitric oxide (NO) is a key signaling molecule regulating plant stress responses. In our study, the NO donor sodium nitroprusside (SNP) significantly promoted ginger seedling growth under salt stress, while treatment with the NO scavenger cPTIO resulted in an opposite response, supporting the involvement of NO in salt-stress responses. Transcriptome profiling of ginger leaves identified 2252 differentially expressed genes (DEGs), which were enriched in 55 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Further, analysis showed that 19 DEGs were enriched in plant hormone signal transduction, while 16 DEGs were enriched in starch and sugar metabolism. NO treatment increased the levels of indole-3-acetic acid (IAA), gibberellin 3 (GA3), and trans-zeatin (ZR), while reducing the levels of abscisic acid (ABA), methyl jasmonate (MeJA), and brassinosteroid (BR). Moreover, NO promoted the accumulation of soluble sugars and sucrose and enhanced the activities of key enzymes involved in starch and sucrose metabolism, thereby effectively improving osmotic adjustment. Collectively, NO improves antioxidant capacity, maintains endogenous phytohormone balance, and enhances osmotic adjustment, ultimately alleviating salt stress damage in ginger seedlings.