Xu Z, Ali Z, Xu L, He X, Huang Y, Yi J, Shao H, Ma H, Zhang D.

Sci Rep. 2016 Feb 3;6:20366. doi: 10.1038/srep20366.

Abstract

Plant basic-leucine zipper (bZIP) transcription factors play important roles in many biological processes and are involved in the regulation of salt stress tolerance. Previously, our lab generated digital gene expression profiling (DGEP) data to identify differentially expressed genes in a salt-tolerant genotype of Glycine soja (STGoGS) and a salt-sensitive genotype of Glycine max (SSGoGM). This DGEP data revealed that the expression (log2 ratio) of GmbZIP110 was up-regulated 2.76-fold and 3.38-fold in SSGoGM and STGoGS, respectively. In the present study, the salt inducible gene GmbZIP110 was cloned and characterized through phylogenetic analysis, subcellular localization and in silico transcript abundance analysis in different tissues. The functional role of this gene in salt tolerance was studied through transactivation analysis, DNA binding ability, expression in soybean composite seedlings and transgenic Arabidopsis, and the effect of GmbZIP110 on the expression of stress-related genes in transgenic Arabidopsis was investigated. We found that GmbZIP110 could bind to the ACGT motif, impact the expression of many stress-related genes and the accumulation of proline, Na(+) and K(+), and enhanced the salt tolerance of composite seedlings and transgenic Arabidopsis. Integrating all these results, we propose that GmbZIP110 plays a critical role in the response to salinity stress in soybean and has high potential usefulness in crop improvement.

See: http://www.ncbi.nlm.nih.gov/pubmed/26837841

Figure 1: Phylogenetic analysis of the bZIPs and domain analysis and subcellular localization of the GmbZIP110 protein.

(a) Phylogenetic tree containing full length soybean bZIPs, including GmbZIP110 (indicated by an arrow) and Arabidopsis bZIP proteins. A multiple sequence alignment containing the amino acid sequences of all bZIP proteins was performed using ClustalX2. The phylogenetic tree was constructed using the Neighbor-Joining method with the MEGA software. The bZIP transcription factors were divided into 13 subfamilies titled I–XIII. AtbZIP TFs were divided into 10 subfamilies titled A, B, C, D, E, F, G, H, I and S. GmbZIP110 belongs to the XI(S) subfamily, which contains 13 additional GmbZIPs and 9 AtbZIPs. (b) Domain structure of the GmbZIP110 subfamily XI(S): NLS, domain of putative nuclear localization signal under red bar, bZIP domain: basic region/leucine zipper motif of GmbZIP110 protein under black bar, the different background color of amino acid meaning different conserved sequences. (c) Subcellular localization of the GmbZIP110 protein in Arabidopsis protoplasts. A construct encoding a GmbZIP110-green fluorescent protein fusion (p35S::GmbZIP110-GFP) was created using the pJIT166-GFP vector. The GmbZIP110 was introduced without a termination codon, creating an in-frame fusion between the GmbZIP110 CDS and GFP. The fusion construct and the GFP control plasmid (p35S::GFP) were transformed into Arabidopsis protoplasts using PEG4000. The transformed Arabidopsis protoplasts were incubated for 18–24 h at room temperature and observed under a confocal fluorescence microscope. The nucleic acid stain Hoechst 33342 was detected using an excitation wavelength of 350 nm and an emission wavelength of 461 nm. Chloroplast auto-fluorescence was detected using an excitation wavelength of 480 nm and an emission wavelength of 685 nm. Scale bars = 10000 nm.