Ontogenetic scaling and similar patterns of cell proliferation and growth explain the differences in corolla tube length between two Salvia species with different pollinators

DAVIES AGUSTÍN; BENÍTEZ-VIEYRA SANTIAGO

Congreso; III Virtual Meeting of Systematics, Biogeography, and Evolution (SBE): New Roles and Challenges of Biodiversity Research; 2022

Pollinator-mediated selection is considered one of the main drivers in the evolutionand diver sification of Angiosperm flowers. Even though differences in morphologyare often examined in mature flowers, they may arise due to changes during development. In this sense, corolla tube length is a key trait that plays a crucial rolein specialized plant-pollinator interactions. Here we compared flower developmentin two phylogenetically close species with contrasting corolla tube lengths: Salviaguaranitica A. St.-Hil. ex Benth. and Salvia stachydifolia Benth. While the firstis pollinated exclusively by hummingbirds, the second is pollinated mainly by bees.We characterized developmental trajectories and examined cell growth and proliferation. Our results showed that corolla tubes grow faster than the corolla upper lip inboth species and at a similar rate. Development trajectories did not differ betweenspecies except in their extension. We also found that corolla tube growth was relatedto cell proliferation during the early stages of bud development and anisotropic cellgrowth throughout the entire process. In addition, we detected differences in therate of anisotropic growth between the corolla tube’s basal, middle, and distal cells.Our results suggest that differences in flower morphology between these two speciesmay have arisen through ontogenetic scaling, i.e. the extension or reduction of developmental trajectories involving similar patterns of cell proliferation and growth.