PwuWRKY48 Confers Drought Tolerance in Populus wulianensis

Populus wulianensis mainly grows in hilly and sloped areas and has strong resistance to adversity. Previous transcriptome studies have shown that a WRKY gene PwuWRKY48 is expression-induced under drought stress. In this study, we aim to characterize the gene's structure and investigate its role in plant drought resistance. The results show that PwuWRKY48 (1113 bp) belongs to a class IIc WRKY subfamily and it was determined as a nuclear localization protein. The gene promoter region contains a variety of cis-elements in relation to stress resistance. Under drought stress, PwuWRKY48 was expression-induced in leaves and stems, 29.7 and 16.6 times those before treatment, respectively. Overexpressing PwuWRKY48 lines were associated with increased activities of peroxidase (POD) and superoxide dismutase (SOD), 2.5 and 1.6 times higher than those of the wild type. While malondialdehyde content (MDA), superoxide anion radical (O-2(.-)), and relative conductivity were decreased by 20%, 30%, and 21.3%, proline and chlorophyll contents increased by 37.5% and 11.2%, respectively. This indicates that PwuWRKY48 efficiently improved the drought tolerance of transgenic plants. PwuWRKY48 can be used as a gene resource for molecular breeding of plant drought resistance.