Genome-Wide Identification, Evolutionary Patterns, and Expression Analysis of bZIP Gene Family in Olive (Olea europaea L.)

Olive (Olea europaea.L) is an economically important oleaginous crop and its fruit cold-pressed oil is used for edible oil all over the world. The basic region-leucine zipper (bZIP) family is one of the largest transcription factors families among eukaryotic organisms; its members play vital roles in environmental signaling, stress response, plant growth, seed maturation, and fruit development. However, a comprehensive report on thebZIPgene family in olive is lacking. In this study, 103OebZIPgenes from the olive genome were identified and divided into 12 subfamilies according to their genetic relationship with 78 bZIPs ofA. thaliana. MostOebZIPgenes are clustered in the subgroup that has a similar gene structure and conserved motif distribution. According to the characteristics of the leucine zipper region, the dimerization characteristics of 103 OebZIP proteins were predicted. Gene duplication analyses revealed that 22OebZIPgenes were involved in the expansion of thebZIPfamily. To evaluate the expression patterns ofOebZIPgenes, RNA-seq data available in public databases were analyzed. The highly expressedOebZIPgenes and several lipid synthesis genes (LPGs) in fruits of two varieties with different oil contents during the fast oil accumulation stage were examined via qRT-PCR. By comparing the dynamic changes of oil accumulation,OebZIP1,OebZIP7,OebZIP22, andOebZIP99were shown to have a close relationship with fruit development and lipid synthesis. Additionally, someOebZIPhad a significant positive correlation with variousLPGgenes. This study gives insights into the structural features, evolutionary patterns, and expression analysis, laying a foundation to further reveal the function of the 103OebZIPgenes in olive.