David's research interests focus on how genes regulate the morphogenesis of flowers. His group uses a small mustard species Arabidopsis thaliana as a model to uncover regulatory genes.
One set of genes is involved in specifying internal parts of carpels, the female reproductive component of flowers. The SPATULA gene promotes development of the tract through which fertilizing pollen tubes grow. It encodes a bHLH transcription factor, and its role is shared by two other family members, ALCATRA and INDEHISCENT. Study of their joint action has revealed that SPATULA also acts with each of these genes later during seed pod development. Together they help establish the dehiscence zone that allows the ripe seeds to escape.
A current focus is another gene, PETAL LOSS, involved in regulating the development of petals and sepals, the perianth organs of the flower. PETAL LOSS functions to repress growth between newly arising sepals, allowing petal initiation signals to act nearby. The gene encodes a trihelix transcription factor, one of 30 in Arabidopsis. The group are now working to understand the structure and function of the PETAL LOSS protein, its regulation, and to uncover the signals involved in petal initiation.