A Glycine soja S1 group bZIP transcription factor GsbZIP43 is a positive regulator of sodium bicarbonate stress tolerance

Soil salinization-alkalization has long restricted the yield and quality of crops. As a key factor in the regulation of gene expression, transcription factor (TF) controls the growth and development of crops. The basic leucine zipper (bZIP) family is one of the largest TF families in plants and has been widely reported regulating plant growth and development and stress responses. Here, in this study, we identified a sodium bicarbonate tolerance gene, GsbZIP43, by screening the cDNA library generated from the wild soybean G07256 with sodium bicarbonate tolerance. Sequence analysis revealed that GsbZIP43 is a member of S1 bZIP subfamily. The subcellular localization of GsbZIP43-RFP (red fluorescent protein) fusion protein in tobacco leaf cells suggested that GsbZIP43 localizes in cell nucleus. Further transactivation assay uncovered that GsbZIP43 acts as a transcriptional activator and the C-terminal region is vital for transcriptional activation. Overexpression of GsbZIP43 in BY-2 cells, Arabidopsis, and soybean hairy roots enhanced tolerance to sodium bicarbonate stress. Consistently, the loss of its close Arabidopsis homologous gene AtbZIP44 decreased tolerance to sodium bicarbonate stress. Taken together, the above results illustrate the positive role of GsbZIP43 in responding to sodium bicarbonate stress.