Cloning and functional characterization of two GsSnRK1 gene promoters from wild soybean

Sucrose non-fermenting-related protein kinase 1 (SnRK1) belongs to a plant serine/threonine protein kinase family, and is part of a large interactive network of signaling pathways in plants to regulate many aspects of growth and development, and its gene expressions are highly responsive to multiple external stimuli. To functionally characterize the role of different SnRK1 members in wild soybean and identify the expression patterns of novel SnRK1 promoters for transgenic research, in this study, we performed an in silico analysis of the SnRK1 gene family in wild soybean and found GsSnRK1.1 and GsSnRK1.2 are main SnRK1 isoforms in wild soybean. The promoter fragments of both GsSnRK1.1 and GsSnRK1.2 were isolated, and a series of 5′-deletion and the full-length versions of both GsSnRK1.1 and GsSnRK1.2 promoters were fused with GUS reporter gene to generate expression vectors. The GUS activities in different tissues of seedling and adult growth stages of transgenic Arabidopsis plants were determined, and the GUS activities in transgenic Arabidopsis plants under NaCl, NaHCO3, PEG, ABA, MeJA and SA were also analyzed. The results showed that GsSnRK1.1 and GsSnRK1.2 genes have different expression patterns and both promoters may contain enhancers and silencers. In addition, NaCl, NaHCO3, ABA, MeJA, and PEG treatments enhanced, whereas SA treatment decreased the GUS activity under the control of both GsSnRK1.1 and GsSnRK1.2 promoters, which may be due to the distributions of various cis-elements in both GsSnRK1.1 and GsSnRK1.2 promoter regions. These results will contribute to a better understanding of the underlying mechanisms of GsSnRK1 genes in response to various abiotic stresses, and as stress-inducible promoters, GsSnRK1.1 and GsSnRK1.2 promoters can be candidates for practical application in agriculture.