Direct Effects of Polyploidization on Floral Scent

Polyploidy is an important driver of the evolution and diversification of flowering plants. Several studies have shown that established polyploids differ from diploids in floral morphological traits and that polyploidization directly affects these traits. However, for floral scent, which is key to many plant-pollinator interactions, only a few studies have quantified differences between established cytotypes, and the direct effects of polyploidization on floral scent are not yet known. We compared the floral scent of established polyploids and diploids from a natural mixed-ploidy population of the plant Lithophragma bolanderi (Saxifragaceae), a species pollinated by two highly specialized moth pollinators of the genus Greya (Prodoxidae). We also compared the floral scent of neopolyploids synthetically generated from diploids with the floral scent of the diploid progenitors to quantify the direct effects of polyploidization on floral scent. Established tetraploids had a higher floral scent emission rate, produced more scent compounds, and emitted a relative scent composition that differed from diploids. Neotetraploids differed in the same direction from diploids as established tetraploids from diploids, but to a lesser extent. Together, our results provide novel insights into the ways in which polyploidization reshapes floral scent, thereby potentially altering interactions between plants and pollinators.