Séminaire LJC par Edwige MOYROUD

You are welcome to the LJC seminar Thursday, the 7th November at 11 am, Amphi I ENS de Lyon

Edwige Moyroud, University of Cambridge

Under the rainbow : how plants build nanophotonic structures to manipulate the light and attract pollinators.

Birds, beetles and butterflies use nanoscale 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 studied in animals but we still ignore everything about the mechanisms underlying their development. 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. Our group discovered that flowering plants also produce microscopic structures to colour their fruits and flowers. We further showed that 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 on flat petal cells (like that produced by the data grooves on a CD). The particular amplitude and frequency of the striations cause interference, giving rise to an angular colour variation. These striations are part of the cuticle, a hydrophobic layer consisting of a polymer matrix that incorporates waxes and covers the surface of all plant organs. My current work aims to investigate the processes of iridescence development in flowers, by coupling biomechanical modelling and optics with modern genetic analysis, live-tissue imaging and behavioural ecology. To do so, 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.

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