Unraveling the floral aroma of lotus (Nelumbo nucifera): Insights from volatile metabolomics and transcriptomics

Lotus ( Nelumbo nucifera ) is a prominent ornamental plant renowned for its delightful floral aroma. We conducted an integrated analysis of volatile metabolomics and transcriptomics to investigate the composition and emission patterns of lotus floral aromas. A total of 1430 volatile organic compounds (VOCs) were identified across different flower organs, with stamens identified as the primary source. Notably, 1072 VOCs were detected in the stamens during various flowering stages, particularly on the day of flowering (S2) and the day after (S3), which were crucial for scent emission. The major contributors to the aroma included terpenoids, esters, and ketones. Transcriptome analysis identified 13,034 differentially expressed genes (DEGs) across various stages of stamen development. These DEGs were predominantly enriched in metabolic pathways and the biosynthesis of secondary metabolites. The expression of DEGs closely correlated with the accumulation profiles of VOCs, which increased during stages S2 and S3, before decreasing at stage S4, two days after flowering. Integrated analysis revealed that specific structural genes from the mevalonate (MVA) and 2- C -methyl-D-erythritol-4-phosphate (MEP) pathways significantly influence terpenoid biosynthesis and floral aroma formation. These findings deepen our understanding of lotus floral aroma and provide a foundation for the genetic improvement of floral aroma traits in lotus. • Stamen is the primary flower organ for aroma emission in lotus. • The day of flowering and one day after being crucial stages for aroma emission. • Terpenoids, esters, and ketones are the major contributors to floral aromas. • The key gene resources involved in the formation of floral aromas were identified.