Genome-wide identification of the chalcone synthase (CHS) family in tigernut and function analysis of cechs57 in drought stress response

Drought stress is a major abiotic constraint that severely impairs crop growth and reduces yield globally. Identification of drought-tolerant candidate genes and their application in molecular breeding represent effective strategies to alleviate drought-induced losses. Genome-wide identification of CHS family members was performed based on conserved domain screening. Comprehensive bioinformatic analyses, including phylogenetic classification, conserved motif profiling, gene structure annotation and cis -acting, were conducted to characterize the CeCHS family. Transcriptome data were used to analyze expression patterns of CeCHSs under drought stress and screen candidate genes. Functional validation of the candidate gene CeCHS57 was carried out via heterologous expression in yeast and Arabidopsis thaliana . A total of 66 CeCHS genes were identified in the tigernut genome, which were phylogenetically classified into four distinct subfamilies. Members within the same subfamily shared highly conserved motif compositions, exon–intron structures and cis -element profiles. Subfamily B, the dominant clade of the CeCHS family, was abundantly enriched with drought-responsive regulatory elements including ABRE and MBS. CeCHS57 was selected as the core candidate gene based on its sustained high expression in both roots and leaves and strong drought responsiveness. Functional assays indicate that heterologous overexpression of CeCHS57 significantly improves drought tolerance in both yeast and transgenic Arabidopsis . Further physiological characterization supports a mechanism whereby CeCHS57 confers drought resistance through coordinated activation of enzymatic and non-enzymatic antioxidant systems, enhanced reactive oxygen species scavenging, and alleviated membrane lipid peroxidation. This study provides comprehensive systematic information on the CeCHS gene family in tigernut, and identifies CeCHS57 as a promising candidate for molecular breeding of drought-tolerant tigernut varieties.