Isolation and Characterization of Homeodomain-Leucine Zipper III Protein 1 Gene in Poplar

Transcription factors are the regulatory proteins which activate or repress their target genes. We isolated homeodomainleucine zipper III (PagHD-ZIP III_1) gene, a plant-specific transcription factor known to play crucial roles in plant development, from poplar (Populus alba × P. glandulosa). The PagHD-ZIP III_1 is 2,723 base pairs long and encodes a putative 838 amino acid protein with an expected molecular mass of 92.3 kDa. The PagHD-ZIP III_1 protein has four conserved regions including HD, bZIP, START and MEKHLA. Southern blot analysis indicated that PagHD-ZIP III_1 belong to a small gene family in the poplar genome. PagHD-ZIP III_1 is expressed highly in the stem. Moreover, the expression of PagHD-ZIP III_1 is induced by salt, cold, wounding and a plant hormone JA. Our results indicate that PagHD-ZIP III_1 is involved in abiotic stress response and hormonal signaling in poplar.