Whole-Genome profiling of WRKY transcription factors and functional investigation of SsWRKY75 in Schima superba

• 82 WRKY family members were identified from the genome of mugwort in Schima superba . • SsWRKY75 plays an active role in response to drought stress. • SsWRKY75 mainly improved plant drought resistance by regulating ROS balance. • Y1H, EMSA and other experiments showed that SsWRKY75 and PER17 interacted to regulate ROS levels. Schima superba occupies a dominant position in the native subtropical evergreen broad-leaved forests of South China. It serves as an important raw material for wood products. However, seasonal droughts resulting from environmental changes in recent decades have significantly constrained tree growth in South China . WRKY is one of the most important transcription factors in plants, present analysis characterized 82 WRKY genes within the S. superba , among which SsWRKY75 was selected for subsequent investigation. Subcellular localization investigation confirmed that SsWRKY75 is predominantly found in the nucleus. Experimental findings indicated that SsWRKY75 overexpression markedly improved drought resilience in transgenic Arabidopsis thaliana , thereby confirming its contribution to augmented drought tolerance in S. superba . Furthermore, under water-limiting conditions, the transcriptional levels of stress-inducible genes, including AtSOD, AtCAT1, AtPOD1 , was markedly upregulated in transgenic Arabidopsis thaliana . In addition, electrophoretic mobility shift assay, combined with yeast one-hybrid as well as virus-induced gene silencing analyses, demonstrated a direct regulatory relationship between SsWRKY75 and SsPER17 , a key functional gene for drought tolerance found in previous studies. These findings suggest that SsWRKY75 enhances the reactive oxygen species elimination efficiency in plants experiencing drought stress via targeting the cis-regulatory element at the promoter site of the peroxidase-encoding gene SsPER17 , thereby promoting root growth and development. These findings advances of our understanding of how WRKY genes mediate plant adaptation to drought conditions.