Abstract
Abscisic acid (ABA) plays crucial roles in plant development and adaption to environmental stresses. The ABA-responsive element binding protein/ABRE-binding factor and ABA INSENSITIVE 5 (AREB/ABF/ABI5) gene subfamily members, which belong to the basic domain/leucine zipper (bZIP) transcription factors family, participate in the ABA-mediated signaling pathway by regulating the expression of their target genes. However, information about potato (Solanum tuberosum) AREB/ABF/ABI5 subfamily members remains scarce. Here, seven putative AREB/ABF/ABI5 members were identified in the potato genome. Sequences alignment revealed that these members shared high protein sequence similarity, especially in the bZIP region, indicating that they might possess overlapping roles in regulating gene expression. Subcellular localization analysis illustrated that all seven AREB/ABF/ABI5 members were localized in the nucleus. Transactivation activity assays in yeast demonstrated that these AREB/ABF/ABI5 members possessed distinct transcriptional activity. Electrophoretic mobility shift assays (EMSA) confirmed that all of these AREB/ABF/ABI5 members could have an affinity to ABRE in vitro. The expression patterns of these AREB/ABF/ABI5 genes showed that they were in response to ABA or osmotic stresses in varying degrees. Moreover, most AREB/ABF/ABI5 genes were induced during stolon swelling. Overall, these results provide the first comprehensive identification of the potato AREB/ABF/ABI5 subfamily and would facilitate further functional characterization of these subfamily members in future work.
Highlights
As sessile organisms, higher plants have evolved adaptive robustness to environmental variation
A comprehensive analysis of the seven AREB/ABF/ABI5 members in the potato genome was conducted in the current research
The nuclear location of seven AREB/ABF members was confirmed by the transient expression assay, suggesting that they might act as transcription factors to function in the nucleus
Summary
Higher plants have evolved adaptive robustness to environmental variation. The present study characterized the structure, phylogenetic relationship, subcellular localization, transactivation activity, DNA binding activity, and expression profiles of whole AREB/ABF/ABI5 subfamily members in potato. It was found that StAREB1, StAREB2, and StAREB4, which belonged to the same phylogenetic clade of Arabidopsis AREB1/ABF2, AREB2/ABF4, ABF3, and ABF1 (Figure 1), were dramatically induced by ABA, water deficit, and high salinity These three potato AREB/ABF transcription factors behave in terms of gene structure, nuclear localization, transactivation activity in yeast, and ABRE binding activity in vitro. Considering these data, it was reasonable to speculate that StAREB1, StAREB2, and StAREB4 might function redundantly in regulating ABRE-dependent ABA signaling involved in osmotic stress. It will be of interest to investigate the specific function of potato endogenous AREB/ABF/ABI5 genes in tuberization
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