Water stress tolerance, genomic selection and identification of genomic regions in a MAGIC population of eggplant

Horticultural crops are increasingly affected by water stress due to climate change, making the development of stress-tolerant varieties essential. In this study, we evaluated 184 multi-parent advanced generation inter-cross (MAGIC) eggplant lines under water stress conditions, consisting of irrigation at 30% of field capacity. After 21 days of stress, we assessed growth-related traits, water content, plant pigments, and proline content. The MAGIC population showed high variability for water stress tolerance, with several transgressive lines surpassing parental values. Key traits related to water stress tolerance included increased root growth and higher levels of proline and flavonoids. Genome-wide association study (GWAS) analysis identified three genomic regions linked to total dry weight, water content, and flavonoid content-traits associated with performance under water stress. Additionally, a linear genomic selection index was constructed based on total dry weight, dry weight increase during the stress period, root dry weight, water content, and proline content. This index was used to predict stress tolerance in 141 unevaluated MAGIC lines, with prediction accuracies ranging from 0.11 to 0.53. This study highlights critical traits, genomic regions, and lines with potential for breeding, providing valuable information for future efforts to improve water stress tolerance in eggplant.