Evolutionary and Expression Analyses of Basic Zipper Transcription Factors in the Highly Homozygous Model Grape PN40024 (Vitis vinifera L.)

Abstract

Basic leucine zipper (bZIP) proteins, which function as transcription factors and play important regulatory roles in all eukaryotic organisms, have been identified and classified in plants based on the sequenced genomes of model species such as Arabidopsis thaliana and rice (Oryza sativa). However, far less is currently known about the evolutionary relationships and expression patterns of bZIP genes in nonmodel plants. In this study, we performed a genome-wide analysis and identified a total of 47 bZIP transcription factors from grape (Vitis vinifera L., cv PN40024). Phylogenetic analysis of grape bZIP transcription factors along with their Arabidopsis and rice counterparts indicated that they can be classified into 13 different groups. Furthermore, evolutionary analysis of the grape bZIP transcription factors demonstrated that segmental duplications have contributed substantially to the expansion of this family in grape. In addition, synteny analysis between grape and Arabidopsis suggested that some of the bZIP members were present in their most recent common ancestor and that the major expansion occurred before the divergence of the two species. Gene expression analysis of the grape bZIP transcription factor-encoding genes revealed tissue-specific, biotic and abiotic stress and hormone-responsive expression profiles. Taken together, the genome-wide identification and characterization of grape bZIP transcription factors provide insights into their evolutionary history and a resource for further functional characterization in the context of crop improvement and stress tolerance.