Stenotaphrum secundatum is an excellent shade-tolerant warm-season turfgrass. Its poor cold resistance severely limits its promotion and application in temperate regions. Mining cold resistance genes is highly important for the cultivation of cold-resistant Stenotaphrum secundatum. Although there have been many reports on the role of the Shaker potassium channel family under abiotic stress, such as drought and salt stress, there is still a lack of research on their role in cold resistance. In this study, the transcriptome database of Stenotaphrum secundatum was aligned with the whole genome of Setaria italica, and eight members of the Shaker potassium channel family in Stenotaphrum secundatum were identified and named SsKAT1.1, SsKAT1.2, SsKAT2.1, SsKAT2.2, SsAKT1.1, SsAKT2.1, SsAKT2.2, and SsKOR1. The KAT3-like gene, KOR2 homologous gene, and part of the AKT-type weakly inwardly rectifying channel have not been identified in the Stenotaphrum secundatum transcriptome database. A bioinformatics analysis revealed that the potassium channels of Stenotaphrum secundatum are highly conserved in terms of protein structure but have more homologous members in the same group than those of other species. Among the three species of Oryza sativa, Arabidopsis thaliana, and Setaria italica, the potassium channel of Stenotaphrum secundatum is more closely related to the potassium channel of Setaria italica, which is consistent with the taxonomic results of these species belonging to Paniceae. Subcellular location experiments demonstrate that SsKAT1.1 is a plasma membrane protein. The expression of SsKAT1.1 reversed the growth defect of the potassium absorption-deficient yeast strain R5421 under a low potassium supply, indicating that SsKAT1.1 is a functional potassium channel. The transformation of SsKAT1.1 into the cold-sensitive yeast strain INVSC1 increased the cold resistance of the yeast, indicating that SsKAT1.1 confers cold resistance. The transformation of SsKAT1.1 into the salt-sensitive yeast strain G19 increased the resistance of yeast to salt, indicating that SsKAT1.1 is involved in salt tolerance. These results suggest that the manipulation of SsKAT1.1 will improve the cold and salt stress resistance of Stenotaphrum secundatum.

Elucidating the response mechanisms of seashore paspalum (Paspalum vaginatum) roots to salt stress is crucial for breeding salt-tolerant varieties. This study aimed to investigate the morphological, physiological, and surface electrochemical responses of seashore paspalum roots to salt stress. The salt-tolerant genotype Sealsle2000 and salt-sensitive genotype 17U-45 were subjected to 300 mM salt stress for 4 and 8 days. Results showed that salt stress exerted a more pronounced inhibitory effect on root growth than on shoot growth, with Sealsle2000 exhibiting less growth inhibition compared to 17U-45. Under salt stress, Sealsle2000 adsorbed more Na⁺ on the root surface and sequestered them within the roots than 17U-45; furthermore, Sealsle2000 was able to maintain higher K⁺/Na⁺ ratios. In terms of physiological mechanisms, Sealsle2000 maintained higher activities of superoxide dismutase and catalase, as well as elevated levels of osmotic adjustment substances (proline and soluble sugars) in roots, which collectively alleviated membrane lipid peroxidation damage and osmotic stress. Compared to 17U-45, Sealsle2000 possessed more negative charges and functional groups on the root surface, which contributed to its higher Na⁺ adsorption capacity and enhanced salt tolerance. Collectively, these findings establish a theoretical framework for understanding the salt tolerance mechanisms of seashore paspalum and other plants.