The genome of giant waterlily provides insights into the origin of angiosperms, leaf gigantism, and stamen function innovation.

As some of the earliest evolving flowering plants, waterlilies offer unique insights into angiosperm evolution. Giant Amazonian waterlilies (genus Victoria) are of particular interest due to their production of the world's largest floating leaves and gigantic flowers that entrap pollinating beetles. Here, we report chromosome-level genome assemblies of Victoria cruziana and three related waterlilies: Euryale ferox, Nymphaea mexicana, and Brasenia schreberi. We found an ancient whole-genome duplication event specific to the Nymphaeales. We reveal major gene duplication and loss events throughout the evolution of angiosperms, with substantial implications for flower development and the biosynthesis of floral volatile organic compounds (FVOCs) in waterlilies. Importantly, we report a unique division of labor in the stamen function of V. cruziana linked to beetle attraction by FVOCs. This is related to the ultra-high expression of VicSABATHa along with Vicchitinase, possibly linked to protection from damage by trapped beetles. Overexpression of VicSABATHa in tobacco leaves reveals a capacity to produce volatile fatty acids, confirming its role in their catalytic synthesis. Overall, these findings provide novel insights into the evolution and adaptations of waterlilies and flowering plants in general.