4 Discussion
Previous studies have reported that UV-B radiation can adversely affect plants and cause oxidative damage (Kakani et al., 2003; Shi & Liu, 2021). In this study, we confirmed that after UV-B treatment (16 kJ m-2 d-1), the ROS content in the leaves of G. hirsutum significantly increased, and the leaf damage subsequently appeared after two days (Fig. 1). Although flavonoids, glutathione, phenolic compound, terpenoid, and phenylpropanoid (Dias et al., 2020; Xie et al., 2022) all played critical roles in ROS scavenging under UV-B stress, few studies have focused on the entire metabolic pathway of the antioxidants to investigate their molecular operating mechanisms. Particularly in polyploid plants, such as G. hirsutum, two separated and parallel metabolic pathways are combined into a common nucleus through hybridization and whole genome doubling. The evolutionary mechanism of the duplicated pathways is still largely unknown. Here, using the GSH pathway as an example, we investigated the gene composition, expression pattern, and regulatory network of the duplicated pathway during evolution and focused on the response performance of the pathway to UV-B stress in the tetraploid cotton. This study lays the foundation for better elucidation of the molecular dynamics of specific pathway in polyploid plants.