Abstract
The basic leucine zipper (bZIP) transcription factors play important regulatory roles, influencing plant growth and responses to environmental stresses. In the present study, 132 bZIP genes identified in the tobacco genome were classified into 11 groups with Arabidopsis and tomato bZIP members, based on the results of a phylogenetic analysis. An examination of gene structures and conserved motifs revealed relatively conserved exon/intron structures and motif organization within each group. The results of an investigation of whole-genome duplication events indicated that segmental duplications were crucial for the expansion of the bZIP gene family in tobacco. Expression profiles confirmed that the NtbZIP genes are differentially expressed in various tissues, and several genes are responsive to diverse stresses. Notably, NtbZIP62, which was identified as an AtbZIP37/ABF3 homolog, was highly expressed in response to salinity. Subcellular localization analyses proved that NtbZIP62 is a nuclear protein. Furthermore, the overexpression of NtbZIP62 in tobacco significantly enhanced the salt stress tolerance of the transgenic plants. The results of this study may be relevant for future functional analyses of the bZIP genes in tobacco.
Highlights
Transcription factors (TFs) are important regulators of plant growth and development that bind to specific regions of target gene promoters to activate or suppress expression [1,2].Including the basic leucine zipper (bZIP) TF family, more than 60 TF families have been identified in the plant kingdom [3]
For the convenience of further research, we renamed the newly identified bZIP genes from NtbZIP1 to NtbZIP132 based on their physical locations on each chromosome/scaffold
The systematic analysis of the tobacco genome in this study identified 132 NtbZIP
Summary
Transcription factors (TFs) are important regulators of plant growth and development that bind to specific regions of target gene promoters to activate or suppress expression [1,2]. Including the bZIP TF family, more than 60 TF families have been identified in the plant kingdom [3]. Plant bZIP proteins generally bind to the ACGT core of the target gene promoter sequence and to the A-box (TACGTA), C-box (GACGTC), and G-box (CACGTG), in order of affinity [7]. In Arabidopsis, 78 bZIP members have been identified and were divided into 13 groups. Among the Group A members, AtbZIP39/ABI5 affects floral transitions by regulating the transcription of the gene encoding flowering site C (FLC), which suppresses the gene encoding the florigen flowering locus T (FT) [10].
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