Genome-Wide Identification of the SnRK2 Gene Family and Its Response to Abiotic Stress in Populus euphratica

Improving plant water use efficiency (WUE) and drought tolerance by modulating stomatal activity constitutes a promising strategy for mitigating the impacts of water scarcity. <i>SnRK2</i>, a key component of the abscisic acid (ABA) signaling pathway, plays a critical role in modulating stomatal behavior under abiotic stress. However, the functional role of <i>SnRK2</i> in regulating stomatal movement to enhance WUE and drought tolerance in <i>Populus euphratica</i> remains to be characterized. In this study, 11 <i>PeSnRK2</i> genes were identified in the <i>P. euphratica</i> genome, each comprising 9-14 exons and exhibiting an uneven distribution across seven chromosomes. Subcellular localization predictions indicated that these proteins are predominantly localized in the Cytoplasm and Cytoskeleton. Phylogenetic analysis grouped the <i>PeSnRK2</i> genes into three distinct subfamilies, and conserved gene structures were observed within each clade. Analysis of cis-acting regulatory elements suggested that <i>PeSnRK2</i> genes were involved in hormonal signaling and stress response pathways. Further transcriptomic data also indicated substantial alterations in <i>PeSnRK2</i> expression due to polyethylene glycol (PEG) and abscisic acid (ABA) treatment. Finally, qRT-PCR and subcellular localization showed that <i>PeSnRK2.6</i> is highly induced by ABA and functions in both nucleus and cytoplasm. This first characterization in a desert woody species bridged gaps in <i>SnRK2</i> evolution and function.