The basic leucine zipper (bZIP) transcription factor family is one of the largest and most diverse transcriptional regulators among eukaryotic organisms. Studies have demonstrated that bZIP transcription factors were involved in diverse physiological processes in plant growth and development. Castor bean (Ricinus communis L., Euphorbiaceae) is one of the most important non-edible oilseed crops and its seed oil is broadly used in industry.
Based on sequence similarity of the basic region and the presence or absence of additional conserved motifs, the characterization of bZIP genes has been annotated for Arabidopsis, rice and maize. However, limited is known about the holistic profiles of structural and functional annotation in bZIP genes in other plants because of the limited availability of complete genome.
Researchers from Molecular Genetics and Genetic Engineer Group of Xishuangbanna Tropical Botanical Garden (XTBG) identified and characterized bZIP transcription factors based on the complete genome sequences of castor bean. Using high-throughput sequencing for digital gene expression tag profiling (DGE), they examined global expression profiles of the castor bean bZIP genes among different tissues.
In total, 49 RcbZIP transcription factors were identified, characterized and categorized into 11 groups (I–XI) based on their gene structure, DNA-binding sites, conserved motifs, and phylogenetic relationships. The 49 bZIP transcription factors were characterized according to the conserved amino acid residues within bZIP domain, the conserved motifs and gene organization in structure, phylogenetical analysis, and global expression profiles among different tissues using high-throughput sequencing.
Results obtained from their study provided holistic information in understanding the molecular basis of the bZIP gene family in castor bean and other plants in the family Euphorbiaceae as well.