#100-61 Overexpressing CHX20 promotes stomatal conductance and carbon assimilation in water-deficit plants

Water deficit stress severely affects agricultural productivity globally by causing physiological changes such as reduced photosynthesis and accelerated leaf senescence. In this study, genome-wide association studies and expression quantitative trait loci mapping in Populus trichocarpa identified a genetic locus associated with drought-induced leaf senescence, encoding a Cation/H+ antiporter CHX20. Transgenic poplar lines overexpressing CHX20 maintained a high assimilation rate, stomatal conductance, photosynthetic efficiency, and leaf water potential under water-deficit conditions. Similarly, transgenic Arabidopsis thaliana, overexpressing AtCHX20 showed greater stomatal aperture, transpiration rates, and osmolyte contents over WT and KO under water-deficit stress. Together, results from both Populus and Arabidopsis demonstrate that overexpressing CHX20 allows stomatal opening and promotes photosynthetic efficiency without yield penalties. These findings emphasize the importance of the CHX20 antiporter in maintaining stomatal opening under water-deficit stress, highlighting CHX20 as a valuable target for genetic engineering to alleviate the impacts of drought in a changing environment.