SlPIP1;7 enhances tomato acclimation to high VPD through optimizing stomatal morphology and regulating ROS

Vapor pressure deficit (VPD), defined as the difference between the actual water vapor pressure and the saturation vapor pressure in the air, is a core indicator of atmospheric aridity. High VPD induces intensified water loss via plant transpiration, thereby constraining water uptake and photosynthetic capacity. The dynamic functions and molecular regulatory mechanisms of plasma membrane intrinsic proteins (PIPs), key aquaporins mediating rapid transmembrane water transport, remain unclear during plant responses to high VPD stress. In this study, we elucidated the regulatory role of SlPIP1;7 in regulating the multi-level adaptation strategy of tomato (Solanum lycopersicum) at the morphological, physiological, and molecular levels under high VPD conditions. The results indicate that, compared to wild-type (WT) plants, SlPIP1;7 overexpressing (OE) plants exhibit superior growth performance under high VPD conditions. The overexpression of SlPIP1;7 significantly enhances the reactive oxygen species (ROS) scavenging efficiency, effectively protecting plant cells from oxidative damage. This protective mechanism for maintaining ROS homeostasis is closely associated with stomatal function. The overexpression of SlPIP1;7 can regulate stomatal morphology, size, and aperture dynamics, thereby promoting efficient utilization of water and carbon dioxide and enhancing the overall physiological regulatory capacity of plants under stress conditions. Additionally, we identified the ethylene response factor SlERF4 as an upstream regulatory factor in this adaptive network. Yeast one-hybrid (Y1H) and dual-luciferase (LUC) assays demonstrate that the transcription factor SlERF4 can bind to the SlPIP1;7 promoter, enhancing its expression and functionality. This interaction further underscores the pivotal role of SlPIP1;7 in combating high VPD stress. In summary, our study elucidates the crucial function of SlPIP1;7 in plant response and acclimation to high VPD stress. These findings expand our understanding of the molecular mechanisms underlying plant acclimation to environmental stresses and provide a reference for future breeding strategies aimed at developing drought-resistant crops.