TaPSP1 Negatively Regulates Osmotic Stress Response in Wheat.

Abstract

Wheat (Triticum aestivum L.) is a cornerstone of global food security, yet its production is severely threatened by osmotic stress, such as drought-induced water deficit. Identifying and characterizing key genes involved in stress response is crucial for understanding adaptation mechanisms and developing tolerant varieties. In this study, we characterized TaPSP1, a protein containing a peroxiredoxin-like conserved domain, and uncovered its negative regulatory role in the response to osmotic stress. Bioinformatics analysis revealed that TaPSP1 is a hydrophilic, non-secretory protein that is likely localized to the plasma membrane, possessing multiple phosphorylation sites and conserved oxidoreductase domains. Its promoter contains diverse cis-acting elements associated with hormone signaling and environmental responses. Phylogenetic analysis indicated that TaPSP1 is evolutionarily conserved among Poaceae species. Expression profiling showed that TaPSP1 transcript levels gradually decreased under PEG-induced osmotic stress. Functional analysis in transgenic Arabidopsis overexpressing TaPSP1 revealed enhanced sensitivity to osmotic stress, as evidenced by reduced biomass accumulation, lower survival rates, decreased relative water content and proline accumulation, and elevated malondialdehyde levels. Importantly, we further generated TaPSP1-overexpressing transgenic wheat lines, which consistently exhibited an osmotic stress-sensitive phenotype, corroborating the findings from Arabidopsis. Conversely, TaPSP1-RNAi knockdown wheat lines exhibited significantly enhanced osmotic stress tolerance, with increased survival rates, higher proline accumulation, and reduced malondialdehyde content under PEG treatment, providing direct loss-of-function evidence for its negative regulatory role. Transcriptomic analysis further demonstrated that TaPSP1 overexpression broadly reprograms stress-responsive gene expression, suppressing typical defense pathways. Collectively, this study establishes TaPSP1 as a negative regulator of osmotic stress tolerance in wheat, providing a theoretical foundation for improving stress resistance in wheat breeding programs by targeting this negative regulator.