Identification Of BZIP Family In Castor Bean And Analysis Of The Interactions With Lipid Genes

Castor bean (Ricinus communis. L, Euphobiaceae) is one of the most important non-edible oilseed crops. Due to its strong adaptability, high oil content and special fatty acid composition, more and more attention is attracted for its potential development and utilization in biodiesel. Investigation of its molecular mechanism of oil accumulation during seed development is the basis for genetic improvement. In present study, we analysed the characterization of castor bean bZIP family, time and space expression profiles. Further by using yeast one hybrid, we explored the interactions between related bZIP and lipid genes, providing an important basis for further studies of castor bean bZIP family. The major results include as followings:1.49bZIP genes have been identified based on the known bZIP domain sequences from Arabidopsis and rice and castor bean genome sequences. Based on the similarities of conserved DNA-binding domains, RcbZIP genes were systematically classified into11groups.2. Analysis of conserved motifs outside of the bZIP domain, gene structures, and dimerization properties, revealed the correlations between structures and functions in castor bean bZIP family. Phylogenetic relationships analysis by interspecies indicated that bZIP genes are homologous between castor bean and Arabidopsis.3. The expression profiles of bZIP genes in five tissues were analyzed based on our high-throughput DGE expression data. Specific expressed genes(RcbZIP8,31and40) were found in seeds, determined to be closely related to oil accumulation in seeds. Promoter analysis of lipid related genes including Oleosin2, DGAT2and KAR, revealed that ACGT core boxes, bound by bZIP transcription factors, were distributed broadly.4. By using yeast one hybrid, we verified the interactions between RcbZIPs and lipid genes. The results showed that both RcbZIP8and RcbZIP40have the ACGT-specific binding abilities in yeast, indicating that RcbZIP8and RcbZIP40can possiblely regulate these lipid genes by binding ACGT elements, while RcbZIP31not.These results obtained would provide valuable information for understanding the molecular basis of the bZIP transcription factor family and their potential function in regulating the growth and development, particularly in seed filling of castor bean.