Multiomics Uncover the Molecular Basis and Crosstalk Between Floral Scent and Color in Hedychium Varieties

The floral fragrance and color of Hedychium plants affect their ornamental and commercial values. However, several Hedychium varieties with pale colors often emit strong scents, while those with vivid pigmentation have weak or no fragrance; this observation raised the question of whether there is a correlation between floral pigmentation and scent emission traits. Three varieties were used to explore the correlation using multiomics approaches: Hedychium coronarium "ZS" (BJH) with intense aroma and white petals, H. "Jin" (JJH) with weak fragrance and orange-red petals, and Hedychium coccineum "KMH" (HJH) with red petals and scentless. Metabolomic analysis identified 22 anthocyanins and 54 carotenoids. Carotenoids are the primary pigments governing floral coloration of the three varieties, with β-carotene, lycopene, and (E/Z)-phytoene being the predominant ones. Transcriptomic data identified 39, 22, 60, and 25 differentially expressed genes belonging to the anthocyanin, carotenoid, terpenoid, and phenylpropanoid biosynthesis pathways, respectively, with F3'5'H, F3'H, DFR, PSY, LCYB, CRTISO, DXS, GPPS, TPS, CNL, and BSMT considered as key regulatory genes controlling floral aroma and pigment accumulation in Hedychium plants. General linear model fitting revealed a significant negative correlation between floral volatile organic compound (VOC) emissions and carotenoid content, while showing a significant positive correlation with anthocyanidin levels; such coordinated patterns imply integrated regulation of pigment and scent metabolic pathways. Spearman correlation analysis elucidated a significant correlation between 36 biosynthesis genes and 9 metabolites. Through integrated multiomics analysis, we delineated the regulatory networks controlling floral fragrance and pigment accumulation gradients in Hedychium plants.