The aquaporin ScAQP1 from desert moss confers desiccation resilience by integrating water transport and redox homeostasis

• The desert moss S. caninervis retains an ancestral and diverse aquaporin repertoire, from which ScAQP1 emerges as a central hub. • ScAQP1 confers robust desiccation tolerance not only by enhancing water conservation but also by activating coordinated antioxidant defenses, a multifaceted mechanism that is functionally transferable to Arabidopsis . • ScAQP1 is involved in mediating H 2 O 2 homeostasis, likely through peroxiporin-like activity, contributing to cellular protection and showcasing its potential as a genetic resource for engineering climate-resilient crops. Aquaporins (AQPs) are crucial for plant drought adaptation, yet their contributions to the extreme resilience of desiccation-tolerant plants remain largely unclear. This study presents a comprehensive genome-wide analysis of AQPs in the desert moss Syntrichia caninervis , identifying 18 members across seven subfamilies, including ancient lineages that have been largely lost in vascular plants. Integrated transcriptomic and network analysis identified ScAQP1 as a core hub in the stress-responsive network. Functional characterization in both S. caninervis and Arabidopsis thaliana demonstrated that ScAQP1 confers robust drought tolerance by improving water retention and mitigating oxidative stress through enhanced antioxidant systems and proline accumulation. From a mechanistic perspective, the ScAQP1 overexpression yeast experiment indicated that ScAQP1 is involved in regulating the intracellular H 2 O 2 balance. These findings reveal a mechanism in S. caninervis where ScAQP1 functionally integrates hydraulic regulation with redox signaling, distinguishing it from typical water channels. This research provides novel insights into the evolution of AQPs in early land plants and validates ScAQP1 as a potent candidate for engineering stress resilient crops.