Systematic Analysis of Differentially Expressed Maize ZmbZIP Genes between Drought and Rewatering Transcriptome Reveals bZIP Family Members Involved in Abiotic Stress Responses

Abstract

The basic leucine zipper (<i>bZIP</i>) family of transcription factors (TFs) regulate diverse phenomena during plant growth and development and are involved in stress responses and hormone signaling. However, only a few <i>bZIPs</i> have been functionally characterized. In this paper, 54 maize <i>bZIP</i> genes were screened from previously published drought and rewatering transcriptomes. These genes were divided into nine groups in a phylogenetic analysis, supported by motif and intron/exon analyses. The 54 genes were unevenly distributed on 10 chromosomes and contained 18 segmental duplications, suggesting that segmental duplication events have contributed to the expansion of the maize <i>bZIP</i> family. Spatio-temporal expression analyses showed that <i>bZIP</i> genes are widely expressed during maize development. We identified 10 core <i>ZmbZIPs</i> involved in protein transport, transcriptional regulation, and cellular metabolism by principal component analysis, gene co-expression network analysis, and Gene Ontology enrichment analysis. In addition, 15 potential stress-responsive ZmbZIPs were identified by expression analyses. Localization analyses showed that <i>ZmbZIP17</i>, <i>-33</i>, <i>-42</i>, and <i>-45</i> are nuclear proteins. These results provide the basis for future functional genomic studies on <i>bZIP</i> TFs in maize and identify candidate genes with potential applications in breeding/genetic engineering for increased stress resistance. These data represent a high-quality molecular resource for selecting resistant breeding materials.