A large-scale gene co-expression network analysis reveals Glutamate Dehydrogenase 2 (GhGDH2_D03) as a hub regulator of salt and salt-alkali tolerance in cotton

Salt stress and salt-alkali stress significantly inhibit the normal growth and development of plants. Understanding the molecular mechanisms of cotton responses to these stresses is crucial for improve yield and fiber quality. In this study, we conducted a comprehensive analysis of the transcriptome dynamics under salt and salt-alkali stress conditions, utilizing 234 RNA-seq datasets compiled from 11 previous studies. After systematic evaluation and correction for batch effects, we observed that root transcriptomes clustered more consistently than leaf transcriptomes across stress treatment and time points. Weighted gene co-expression network analysis (WGCNA) on 123 root transcriptomes identified three key modules, with their hub genes significantly associated with salt and salt-alkali tolerance. Virus-induced gene silencing assay and RNA-seq analysis indicated that GhGDH2_D03 (Gohir.D03G104800), a module hub gene encoding Glutamate Dehydrogenase 2, positively regulates salt and salt-alkali tolerance in cotton by modulating multiple signaling pathways and metabolic processes, including the ethylene signaling pathway. This study underscores the pivotal role of GhGDH2_D03 in conferring tolerance to salt and salt-alkali stress, in addition to its previous reported involvement in biotic stress defense, providing valuable insights and genetic resources for cotton breeding.