Floral scent is an important ornamental trait in garden plants. Monoterpenes, a major class of terpenoids, constitute the primary volatile components of lily floral scents. 1-Deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) catalyzes the second enzymatic step in the MEP pathway, which supplies precursors for monoterpene biosynthesis. However, the functional role ofthe DXRgene in floral monoterpene production in LiliumOriental Hybrid ‘Sorbonne’ remains unclear. In this study, ‘Sorbonne’ was used as the experimental material, and a differentially expressed LiDXRgene was identified from early transcriptomic data, showing high temporal correlation with the synthesis and emission dynamics of floral volatiles during flowering. The LiDXRgene was cloned and subjected to bioinformatics analysis, revealing that it encodes a protein of 472 amino acids. LiDXRexpression peaked at the half-open floral stage and was significantly higher in petals than in other floral organs. Subcellular localization analysis indicated thatthe LiDXR protein is targeted to chloroplasts in leaf epidermal cells. VIGS of LiDXRreduced monoterpene levels by downregulating the expression of downstream TPSgenes in the MEP pathway. Consistently, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) revealed a significant decrease in total volatile terpene content in silencedlilies. Transgenic Arabidopsisthalianaand petunia plants overexpressing LiDXRexhibited enhanced growth vigor and accelerated flowering. GC-Murashige and Skoog’s (MS) analysis of transgenic petunias showed a 78% increase in total volatile terpenes compared to wild-type plants. Overexpression of LiDXRalso modulated the expression of other MEP pathway genes, thereby influencing the biosynthesis of downstream terpenoids, including monoterpenes. This study elucidates the functional role of LiDXRin terpenoid metabolism and provides a theoretical foundation for floral scent breeding in lily andother ornamental plants.

tea accessions  /  caffeine (CAF)  /  single nucleotide polymorphism (SNP)  /  genome-wide association study (GWAS)  /  Guizhou Plateau