Evolutionary and expression analyses of soybean basic Leucine zipper transcription factor family

Background: Soybean, a major legume crop native to East Asia, presents a wealth of resources for utilization. The basic leucine zipper (bZIP) transcription factors play important roles in various biological processes including developmental regulation and responses to environmental stress stimuli. Currently, little information is available regarding the bZIP family in the legume crop soybean. Results: Using a genome-wide domain analysis, we identified 160 GmbZIP genes in soybean genome, named from GmbZIP1 to GmbZIP160. These 160GmbZIP genes, distributed unevenly across 20 chromosomes, were grouped into 12 subfamilies based on phylogenetic analysis. Gene structure and conserved motif analyses showed that GmbZIP within the same subfamily shared similar intron-exon organizations and motif composition. Syntenic and phylogenetic analyses identified 40 Arabidopsis bZIP genes and 83 soybean bZIP genes as orthologs. By investigating the expression profiling of GmbZIP in different tissues and under drought and flooding stresses, we showed that a majority of GmbZIP (83.44%) exhibited transcript abundance in all examined tissues and 75.6% displayed transcript changes after drought and flooding treatment, suggesting that GmbZIP may play a broad role in soybean development and response to water stress. Conclusions: One hundred sixty GmbZIP genes were identified in soybean genome. Our results provide insights for the evolutionary history of bZIP family in soybean and shed light on future studies on the function of bZIP genes in response to water stress in soybean.