Supplementary information
Figure S1. Phylogenetic tree of WRKY transcription factor family in poplar.
Figure S2. Analysis of PtrWRKY75 overexpression in transgenic poplar plants.
Figure S3. Physiological and photosynthesis parameters of wild-type and transgenic plants under long-term drought conditions.
Table S1. Primer and oligonucleotide sequences used in this study.
Table S2. Accession numbers for WRKY proteins in various plant species.
Table S3. WRKY gene family in Populus.