Pe<scp>CHYR</scp>1, a ubiquitin E3 ligase from <i>Populus euphratica</i>, enhances drought tolerance via <scp>ABA</scp>‐induced stomatal closure by <scp>ROS</scp> production in <i>Populus</i>

Abstract

Summary Drought, a primary abiotic stress, seriously affects plant growth and productivity. Stomata play a vital role in regulating gas exchange and drought adaptation. However, limited knowledge exists of the molecular mechanisms underlying stomatal movement in trees. Here, Pe CHYR 1 , a ubiquitin E3 ligase, was isolated from Populus euphratica , a model of stress adaptation in forest trees. Pe CHYR 1 was preferentially expressed in young leaves and was significantly induced by ABA (abscisic acid) and dehydration treatments. To study the potential biological functions of Pe CHYR 1 , transgenic poplar 84K ( Populus alba × Populus glandulosa ) plants overexpressing Pe CHYR 1 were generated. Pe CHYR 1 overexpression significantly enhanced H 2 O 2 production and reduced stomatal aperture. Transgenic lines exhibited increased sensitivity to exogenous ABA and greater drought tolerance than that of WT (wild‐type) controls. Moreover, up‐regulation of Pe CHYR 1 promoted stomatal closure and decreased transpiration, resulting in strongly elevated WUE (water use efficiency). When exposed to drought stress, transgenic poplar maintained higher photosynthetic activity and biomass accumulation. Taken together, these results suggest that Pe CHYR 1 plays a crucial role in enhancing drought tolerance via ABA ‐induced stomatal closure caused by hydrogen peroxide (H 2 O 2 ) production in transgenic poplar plants.