SlTIP2 ;3 mediates H 2 O 2 transport to activate GA signaling and maintain stomatal conductance under high vapor pressure deficit

SUMMARY As global climate change intensifies, the resultant increase in atmospheric vapor pressure deficit (VPD) significantly affects plant growth and distribution. Under high VPD (HVPD) conditions, plants face a contradiction between increased water evaporation and carbon fixation. A reduction in stomatal conductance ( g s ) can lead to carbon starvation, causing cellular damage or even death. Aquaporins, which are pivotal in water transport, play a crucial role in modulating plant water balance and g s under HVPD conditions; however, the underlying mechanisms remain inadequately understood. Tomato ( Solanum lycopersicum L.) is an important economic crop. This study found that SlTIP2;3 is a key hub for tomato's response to HVPD and regulation of whole‐plant hydraulic conductance ( K plant ) and g s . The overexpression of SlTIP2;3 was observed to increase K plant and g s under HVPD, enhancing water transport and mitigating the decline in g s . Additionally, the overexpression of SlTIP2;3 improved root and stem morphology, optimizing water absorption and distribution. In this context, SlTIP2;3 , as a hydrogen peroxide (H 2 O 2 ) transporter, facilitates H 2 O 2 diffusion into cells, regulating gibberellin (GA) synthesis and signaling, thus enhancing both K plant and g s . This study presents novel evidence indicating that SlTIP2;3 plays a mediating role in the H 2 O 2 –GA signaling pathway, which co‐regulates plant adaptation to HVPD environments and contributes to maintaining high K plant and g s . These findings provide valuable molecular insights into plant responses to climate change‐induced water stress and support the genetic enhancement of drought‐resistant crops.