Quinoa (Chenopodium quinoa Willd.) is a highly nutritious crop known for its tolerance to salt stress; however, the molecular mechanisms underlying this trait remain poorly understood. This study aims to perform the in silico characterisation of calcium-dependent protein kinase (CPK) gene family sequences and to evaluate their expression profiles under salt stress conditions. Using bioinformatics tools, CPK family gene sequences were identified and in silico-characterised, including conserved domains, cis-regulatory motifs, and physicochemical properties. Experimentally, two contrasting accessions were compared: a salt-tolerant one (UNSA_VP033) and a salt-sensitive one (UNSA_VP021). Salt tolerance indices were determined during germination, gene expression levels were quantified by RT-qPCR, and antioxidant enzyme activities, along with malondialdehyde (MDA) content, were evaluated under different NaCl concentrations. Sixteen sequences with characteristic CPK family domains were identified. Promoter analysis revealed cis-elements associated with hormonal and stress responses. Physicochemical parameters predicted proteins of 50–60 kDa with variable isoelectric points. Experimentally, UNSA_VP033 showed the significant overexpression of CqCPK12, CqCPK17, CqCPK20, and CqCPK32, correlated with the higher antioxidant activity of superoxide dismutase (SOD) and peroxidase (POD), and lower MDA levels at 200 mM NaCl. In contrast, the sensitive accession exhibited significant reductions in gene expression and antioxidant activity. In conclusion CPK genes play a key role in the salt stress response in quinoa, particularly CqCPK12, CqCPK17, CqCPK20, and CqCPK32 in the tolerant accession. These findings may contribute to the development of more salt-tolerant varieties, thereby enhancing agricultural sustainability in saline soils.

Quinoa (Chenopodium quinoa) is recognized for its tolerance to abiotic stress, including salinity, and its recent genome sequencing has facilitated the study of the mechanisms underlying this adaptation. This study focused on characterizing the ZAT genes of the C2H2 subfamily in quinoa, evaluating their expression under saline stress. Eight ZAT genes were identified and analyzed in silico using genomic databases and bioinformatics tools, assessing their conserved domains, cis-regulatory motifs, and physicochemical characteristics. Additionally, germination assays, hydroponic cultivation, and gene expression analyses via qPCR were performed on halotolerant (UNSA_VP033) and halosensitive (UNSA_VP021) accessions exposed to different NaCl concentrations. The genes CqZAT4 and CqZAT6 showed high expression in the halotolerant accession under saline stress, correlating with increased dry matter, root length, and water retention. In contrast, the halosensitive accession exhibited lower tolerance, with significant reductions in these metrics. Promoter analysis revealed cis-elements associated with hormonal and stress responses. ZAT genes play a key role in quinoa’s response to saline stress, with CqZAT4 and CqZAT6 standing out in the halotolerant accession. These findings could drive the development of more resilient varieties, contributing to agricultural sustainability in saline soils.