Dose-dependent transcriptional reprogramming and lipid-associated defense under salt stress in mung bean (Vigna radiata)

Abstract

Background: Salt stress severely limits crop productivity worldwide. However, in mung bean (Vigna radiata), an important legume for agriculture and nutrition, the transcriptional mechanisms underlying dose-dependent salt adaptation remain largely unexplored. Results: We combined physiological assays, transcriptomic profiling, and a dose-adapted time-ordered gene co-expression network (TO-GCN) analysis to dissect the regulatory responses of mung bean under a gradient of salt stress concentrations. Salt exposure increased reactive oxygen species and osmolyte accumulation, accompanied by transcriptional reprogramming that intensified with higher salinity. Network analysis identified eight hierarchically organized regulatory layers corresponding to distinct salt stress stages, revealing coordinated activation of ethylene and jasmonic acid signaling pathways. Notably, lipid transfer proteins (VrLTPs) were predominantly induced under high-salt conditions, co-expressed with key transcription factors such as WRKY, MYB, and NAC, and likely function as central regulators of late-stage stress adaptation. Conclusion: These findings reveal a multi-tiered regulatory framework—captured through a dose-responsive TO-GCN approach—integrating hormonal signaling and lipid-mediated defense mechanisms. The identification of VrLTPs as salt-induced transcriptional hubs highlights their critical role in mung bean’s adaptive strategy under high salinity.