Abstract

Beetles and butterflies use minute structures arranged periodically on or just below their surfaces to produce vibrant colours that change with the viewing angle, a phenomenon known as iridescence. The structures responsible for these optical effects have been intensively described but the mechanisms underlying their development remain unknown. In particular, how a living organism can produce a nanopattern with sufficient accuracy that it interferes with light to generate an iridescent signal is a key question.

Flowering plants also produce microscopic structures to colour their fruits and flowers and insect pollinators can use petal iridescence to detect flowers more efficiently. The physical mechanism responsible for this effect is a surface diffraction grating formed by ordered striations of the cuticle on flat petal cells. My project aims to understand how an optically accurate diffraction grating can develop on the surface of a flower petal, by coupling a range of molecular and cell biology tools with optical analysis and behavioural ecology conducted in the Glover lab. As a starting point, I developed a protocol to efficiently transform an iridescent species, Hibiscus trionum. We are now using this new model to determine if mechanical buckling of the cuticle could explain the formation of ordered striations on the petal epidermis.