Expression analysis and in-silico characterization of two terpenoids-biosynthesis related genes in Salvia mirzayanii Rech. f. & Esfand under nano cerium oxide exposure and drought stress

Foliar application of cerium oxide nanoparticles (CeO₂ NPs) mitigates drought stress in Salvia mirzayanii by modulating terpene biosynthesis gene expression. This study evaluated the effects of CeO₂ NPs (0–1000 mg L⁻¹) on 1,8-Cineole Synthase (CS) and Linalool Synthase (Lis) genes under drought (25–100% field capacity, FC) and re-irrigation using a factorial RCBD. The genes (CS, Lis, GAPDH) expression was analyzed using RT-PCR. The phylogenetic relationships of the CS and Lis genes were analyzed based on mRNA and protein sequences. ANOVA revealed significant triple interactions among drought, CeO₂ NPs, and recovery (P < 0.01). Under severe drought (25% FC), foliar spray of 1000 mg L⁻¹ CeO₂ NPs maximized gene expression during recovery, upregulating CS by 2.51-fold and Lis by 2.73-fold compared to controls. Re-irrigation generally reduced expression relative to stress peaks. SEM confirmed spherical NP accumulation (10–30 nm) on leaf surfaces. Phylogenetic analysis grouped S. mirzayanii closely with Lavandula spp., showing high genetic similarity for CS (0.846–0.853). These findings confirm CeO₂ NPs act as effective nano-elicitors, enhancing drought resilience through specific transcriptional modulation of terpene synthase genes.