Comprehensive genome-wide analysis of the gene family of and functional validation of under different abiotic stresses.

Introduction: Hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) is a key enzyme in the terpenoid biosynthetic pathway, playing a crucial role in plant stress responses. However, the gene family in , a traditional Chinese medicinal herb with high steroidal saponin content and strong stress tolerance, remains poorly understood. This study investigates the stress response mechanisms of the gene family in under abiotic stress conditions.

Methods: A comprehensive genome-wide analysis of the gene family in was conducted. The analysis included chromosomal localization, phylogenetic tree construction, linear analysis, gene structure characterization, motif distribution, cis-acting elements, and protein structure. Candidate gene were overexpressed in to analyze phenotypic changes under osmotic and salt stress, including seed germination rate and primary root length. Physiological parameters were also analyzed, and gene expression was validated using qPCR under drought, osmotic, and salt stress conditions.

Results: A total of 18 gene family members were identified in . The functions and evolution of genes are conserved. was selected as a promising candidate due to its unique expression profile. Docking analysis revealed that has conserved motifs for binding both HMG-CoA and NADPH/NADH, showing equal affinity for both. Overexpression of in transgenic enhanced tolerance to abiotic stresses, as evidenced by higher germination rates, improved primary root length, increased chlorophyll and proline levels, enhanced peroxidase (POD) and catalase (CAT) activities, and reduced malondialdehyde (MDA) content compared to non-transgenic plants under stress conditions.

Discussion: These findings highlight the role of in enhancing plant stress tolerance, particularly in combating drought, osmotic, and salt stress. This understanding of its potential function provides avenues for improving crop resilience to abiotic stress through future gene modification.