Isolation, Expression, and Promoter Analysis ofGbWRKY2: A Novel Transcription Factor Gene fromGinkgo biloba
WRKY transcription factor is involved in multiple life activities including plant growth and development as well as biotic and abiotic responses. We identified 28WRKYgenes from transcriptome data ofGinkgo bilobaaccording to conserved WRKY domains and zinc finger structure and selected three WRKY genes, which areGbWRKY2, GbWRKY16, andGbWRKY21, for expression pattern analysis.GbWRKY2was preferentially expressed in flowers and strongly induced by methyl jasmonate. Here, we cloned the full-length cDNA and genomic DNA ofGbWRKY2. The full-length cDNA ofGbWRKY2was 1,713 bp containing a 1,014 bp open reading frame encoding a polypeptide of 337 amino acids. TheGbWRKY2genomic DNA had one intron and two exons. The deducedGbWRKY2contained one WRKY domain and one zinc finger motif.GbWRKY2was classified into Group II WRKYs. Southern blot analysis revealed thatGbWRKY2was a single copy gene inG. biloba. Manycis-acting elements related to hormone and stress responses were identified in the 1,363 bp-length 5′-flanking sequence ofGbWRKY2, including W-box, ABRE-motif, MYBCOREs, and PYRIMIDINE-boxes, revealing the molecular mechanism of upregulated expression ofGbWRKY2by hormone and stress treatments. Further functional characterizations in transiently transformed tobacco leaves allowed us to identify the region that can be considered as the minimal promoter.