Abstract
Background: Glutaredoxins (GRX) are key oxidoreductases that modulate protein redox states during plant development and stress responses. Alkaligrass (Puccinellia tenuiflora) is a highly salt-tolerant forage grass, but its GRX gene family (PutGRXs) remains uncharacterized, unlike those in Arabidopsis and other plants. Results: We identified 25 PutGRX genes in the P. tenuiflora genome. Phylogenetic analysis revealed close evolutionary ties to monocotyledonous rice (Oryza sativa). Based on gene structure and conserved domains, PutGRXs were classified into three groups: five CGFS-type, eleven CPYC-type, and nine CC-type GRXs. Promoter analysis identified numerous cis-acting elements linked to abiotic stresses (e.g., light, drought, heat, cold) and hormone responses, suggesting a pivotal role in stress adaptation. Tissue-specific expression profiling showed differential PutGRX expression in roots, leaves, stems, flowers, and sheaths, with most genes responding to NaCl, NaHCO3, and Na2CO3 stresses. Functional characterization of chloroplast-localized PutGrxS12 demonstrated its importance in plant growth and ROS scavenging under salinity stress. Conclusion: This study offers the first comprehensive genomic and functional analysis of the PutGRX family in P. tenuiflora, highlighting its conservation, classification, and stress-responsive roles. Our findings advance understanding of GRX-mediated stress tolerance and provide potential targets for engineering salt-resistant crops.