GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE338nnn/GSE338036/primaryOK200TranscriptomicsNymphaea colorataExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE338036GEOGSEfalseSpatiotemporal transcriptome atlas of water lily floral organogenesis provide insight into the evolutionary origin of novel traits of angiosperms [RNA-Seq]Petals are a key evolutionary innovation of flowers that reshaped plant-pollinator interactions and underlie the dominance of angiosperms in terrestrial ecosystems, yet their evolutionary origin remains debated as the morphological inferences rarely connect directly to the regulatory programs inferred from extant flowering plants. We employed spatial transcriptome sequencing on serial floral buds of the basal angiosperm Nymphaea colorata, producing a spatiotemporal atlas of cell states during primordium initiation and the subsequent formation of tepals (sepals and petals), stamens and carpels. Our analyses identified multiple meristematic cell populations organized hierarchically at the floral base, with one population give rise to both initiating petals (or inner tepals) and stamens whereas a second population forms carpel primordia. Developmental trajectory reconstruction based on thousands of tissue-preferentially expressed genes uncovers a continuous fate transition from stamen primordia via developing stamens to inner tepals undergoing morphogenesis. Quantitative modeling of MADS-box tetramer composition reveals dosage-sensitive shifts that support the hypothesis that petaloid organs evolved from sterile stamens at the outer whorls. Trajectory modules further show stepwise incorporation of vegetative programs, particularly genes for polarity establishment and photosynthetic essential for leaf development into petal organogenesis. These findings support a model in which petal merger occurred through quantitative retuning and redeployment of ancestral regulatory networks that predate the origin of angiosperms, providing clues for understanding the evolutionary innovation and diversification of petaloid organs across flowering plants.2026/07/10GSE338036GSM9865107GSM9865106GSM9865103GSM9865102GSM9865105GSM9865104GSM9865099GSM9865101GSM986510037192338036Nymphaea colorata