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

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 (H₂O₂) transporter, facilitates H₂O₂ 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 H₂O₂-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.