Heterologous overexpression of the Suaeda glauca stress-associated protein (SAP) family genes enhanced salt tolerance in Arabidopsis transgenic lines

Abstract

Stress-associated proteins (SAPs), characterized by zinc finger domains, play a crucial role in regulating plant responses to various stresses. These proteins modulate stress-related gene expression and are integral to enhancing plant immunity, development, cell proliferation, and hormone regulation. In this study, we conducted a genome-wide analysis of the SAP gene family in Suaeda glauca (S. glauca), identifying 15 SAP genes encoding A20/AN1 zinc finger proteins. Functional analyses of three candidate genes under salinity stress were performed, examining phenotypic and physiological responses to better understand their role in stress tolerance. Sequence alignment, conserved domain analysis, and gene structure analysis revealed high conservation among S. glauca SAPs. Phylogenetic analysis identified two major groups within the gene family, providing insights into their evolutionary relationships. Transcription profiling analysis demonstrated significant expression of most SAP genes in response to salt stress, with qPCR validation confirming the upregulation of specific genes. Notably, transgenic Arabidopsis lines heterologously overexpressing the candidate genes SgSAP4, SgSAP5, and SgSAP7 demonstrated enhanced tolerance to salinity stress. This was evident from improved seed germination, root elongation, and reduced levels of stress markers, including malondialdehyde and free proline, compared to wild-type plants. These findings highlight the potential of these SAP genes in breeding programs aimed at improving salinity tolerance in crops.