A functional nectary must produce and secrete nectar, composed primarily of sugars and water, to the external environment. This process depends on the coordinated activity of multiple cell types across several tissue layers, and the mechanisms involved differ depending on the nectary type. Currently, our understanding of nectar secretion is largely based on mesophyllary nectaries, such as those found in Arabidopsis.

In our search for alternative mechanisms of nectar secretion, we discovered that Aquilegia utilizes an unexpected strategy: epidermal cell rupture. Using imaging and histological techniques, we observed that at anthesis, nectary epidermal cells rupture to create openings through which nectar is released. Prior to rupture, these cells undergo significant cell wall thinning, a process that facilitates bursting and appears to be regulated by members of the STYLISH (STY) family of transcription factors that are key regulators of nectary development in Aquilegia.

To further investigate this novel secretion mechanism, we are combining single-cell RNA sequencing with genetic perturbation experiments to uncover the cellular and molecular basis of nectar secretion in Aquilegia.