Overexpression of GhPAS1 modulates stomatal morphology and canopy architecture to stably improve photosynthetic efficiency and yield in cotton

GhPAS1 coordinately increases stomatal density and decreases stomatal size in cotton, with the abaxial leaf surface making a major contribution to enhanced photosynthesis. GhPAS1 improves photosynthetic capacity and yield via environment-adaptive strategies: regulating stomatal traits under drought stress and promoting canopy expansion under favorable moisture conditions. Molecular and field evidence demonstrates that GhPAS1 integrates brassinosteroid signaling to optimize stomatal Gossypium hirsutum L. is a globally important economic, oil and forage crop, and its yield stability is facing severe challenges. Improving photosynthetic efficiency is a core scientific problem urgently to be solved in the field of cotton genetic improvement and high-yield cultivation. In this study, a brassinosteroid (BR)-responsive basic helix-loop-helix (bHLH) transcription factor GhPAS1 was identified, and two independent overexpression lines (OE-1, OE-2) and wild-type ZM24 were used as materials to carry out gene function identification. A two-year field experiment showed that the effects of GhPAS1 overexpression were stable and consistent across the two growing seasons: the stomatal density (SD) of overexpression lines was increased by 27.9-67.6% and the stomatal size (SS) was decreased by 9.1-26.7% compared with the wild type, and the optimized stomatal structure significantly increased the net photosynthetic rate ( A N ) of leaves in overexpression lines by 13.1-28.0%. Meanwhile, the leaf area index (LAI), canopy light interception efficiency (FIPAR) and canopy photosynthetic rate (CAP) of overexpression lines were increased by 36.5-78.8%, 5.8-9.5% and 24.1-38.5%, respectively, thereby promoting the aboveground biomass and yield to increase by 50.1-78.8% and 21.6-53.6% compared with the wild type. Molecular mechanism analysis showed that GhPAS1 interacted with BR signaling components (BA13, BRI1) and light-responsive factor PRE6, integrating signals to regulate stomatal development and canopy architecture. In conclusion, GhPAS1 stably regulates stomatal and canopy traits, improves photosynthetic efficiency, and promotes yield formation, making it a key functional gene for the improvement of photosynthesis and yield in cotton.