GhVIP1-GhMYB44 module regulates cotton salt tolerance by regulating stress-related genes and enhancing ROS...

Soil salinization severely impacts cotton yield and quality. Excess salt stimulates excessive accumulation of reactive oxygen species (ROS), resulting in oxidative damage and impairment of cell membrane integrity. Therefore, enhancing the antioxidant capacity of cotton is a key strategy to improve salt tolerance. In this study, we systematically characterized the salt tolerance function of GhVIP1, a bZIP family transcription factor. Overexpression (OE) of GhVIP1 enhanced tolerance to salt stress in Arabidopsis, as evidenced by higher germination rates, root length, chlorophyll content, and total antioxidant capacity (T-AOC), along with lower malondialdehyde (MDA) and ROS contents compared to the wild-type (WT). Conversely, virus-induced gene silencing (VIGS) of GhVIP1 resulted in salt-sensitive phenotypes in cotton. Yeast one-hybrid (Y1H) and dual-luciferase (LUC) reporter assays further confirmed that GhVIP1 directly binds to the promoter of GhMYB44 and activated its transcription in vitro. However, genetic analysis revealed that GhMYB44 functions as a negative regulator of salt tolerance, as its silencing significantly enhanced ROS-scavenging capacity and upregulated the expression of ROS-related genes. Notably, silencing GhVIP1 unexpectedly led to elevated GhMYB44 transcript levels in cotton, suggesting the existence of a complex in vivo regulatory network involving additional intermediate factors. Collectively, our results demonstrate that GhVIP1 positively regulates salt tolerance by enhancing ROS detoxification, partially through its interplay with the antagonistic GhMYB44 pathway. This study provides new genetic resources and a theoretical basis for molecular breeding of salt-tolerant cotton.