Characterization and expression analysis of WOX2 homeodomain transcription factor in Aegilops tauschii

The WUSCHEL (WUS)-related homeobox (WOX) gene family coordinates transcription during the early phases of embryogenesis. In this study, a putative WOX2 homolog was isolated and characterized from Aegilops tauschii, the donor of D genome of Triticum aestivum. The sequence consisted of 2045 bp, and contained an open reading frame (ORF), encoded 322 amino acids. The predicted protein sequence contained a highly conserved homeodomain and the WUS-box domain, which is present in some members of the WOX protein family. The full-length ORF was subcloned into prokaryotic expression vector pET-30a, and an approximately 34-kDa protein was expressed in Escherichia coli BL21 (DE3) cells with IPTG induction. The molecular mass of the expressed protein was identical to that predicted by the cDNA sequence. Phylogenetic analysis suggested that Ae. tauschii WOX2 is closely related to the rice and maize orthologs. Quantitative PCR analysis showed that WOX2 from Ae. tauschii was primarily expressed in the seeds; transcription increased during seed development and declined after the embryos matured, suggesting that WOX2 is associated with embryo development in Ae. tauschii.