Physiological, ionomic, transcriptomic and metabolomic analyses reveal molecular mechanisms of root adaption to salt stress in water spinach

Water spinach (Ipomoea aquatica Forsk.) is an important leaf vegetable affected by salt stress, however, little is known about its salt adaption mechanism. Here, we integrated physiomics, ionomics, transcriptomics, and metabolomics to analyze the root adaptation response of two water spinach varieties, BG (salt-tolerant) and MF (salt-sensitive), at 150 mM NaCl. The results showed that compared with MF, BG significantly reduced the content of malondialdehyde (MDA) and H₂O₂, and increased catalase (CAT) activity and proline content. Ionome analysis demonstrated that BG significantly reduced Na⁺ accumulation and increased K⁺ level to reduce the toxicity of Na⁺, compared to MF. Weighted gene co-expression network analysis (WGCNA) revealed that key transcription factors such as HSFA4A, bHLH093, and IDD7, which were only up-regulated in BG. Multi-omics revealed that BG reprogrammed key pathways: starch and sucrose metabolism, as well as galactose metabolism, leading to decreased amylose production and increased sucrose and galactose levels, helping to maintain cellular osmotic balance in response to salt stress. These findings provide insight into transcriptional regulation in response to salt stress, which could advance the genetic enhancement of water spinach.