Salt-Resilient Cowpeas: Early Identification Through Growth Parameters and Gene Expression at Germination Stage

Soil salinity is one of the most severe impacts of climate change, negatively affecting plant growth and development. Seed germination and seedling emergence are among the most critical stages susceptible to salt stress, making it important to explore them to identify the most resilient accessions for crop yield improvement. Cowpea (Vigna unguiculata L. Walp.) is an important crop due to its ability to fix atmospheric nitrogen, improving soil health, and its high protein content. The main objectives of this study were to screen salt-resilient cowpea accessions from a worldwide collection and to evaluate cowpea responses to salt stress at germination stage through gene expression analysis. A total of 40 cowpea accessions from sixteen different countries were subjected to two treatments: control (water) and salt stress (150 mM NaCl solution). The seeds germinated, and the seedlings grew for ten days. The germination and growth parameters and lipid peroxidation quantification were determined. The results revealed significant differences in all parameters among accessions and treatments. A high variation in salt responses was detected among accessions, allowing the selection of five accessions (Co_2, Co_4, Co_21, Co_30, Co_31) as resilient to salt stress at germination stage. Subsequently, two salt stress-related genes (DREB2 and VuEXO) were evaluated through qPCR, revealing genotype-dependent regulation. These results provide valuable insights for the early selection of salt-resilient cowpea accessions, which may be considered for the development of improved and new varieties in the future.