Cuticle chemistry drives the development of diffraction gratings on the surface of Hibiscus trionum petals

• Published in: Current biology 2022-12, Vol.32 (24), p.5323-5334.e6
• Main Authors: Moyroud, Edwige, Airoldi, Chiara A., Ferria, Jordan, Giorio, Chiara, Steimer, Sarah S., Rudall, Paula J., Prychid, Christina J., Halliwell, Shannon, Walker, Joseph F., Robinson, Sarah, Kalberer, Markus, Glover, Beverley J.
• Format: Article
• Language: English
• Subjects: cuticle patterning; diffraction gratings; Flowers - physiology; Hibiscus; Hibiscus - physiology; mechanical buckling; Models, Biological; petal development; plant epidermis; structural color
• ISSN: 0960-9822; 1879-0445; 1879-0445
• DOI: 10.1016/j.cub.2022.10.065

Plants combine both chemical and structural means to appear colorful. We now have an extensive understanding of the metabolic pathways used by flowering plants to synthesize pigments, but the mechanisms remain obscure whereby cells produce microscopic structures sufficiently regular to interfere with light and create an optical effect. Here, we combine transgenic approaches in a novel model system, Hibiscus trionum, with chemical analyses of the cuticle, both in transgenic lines and in different species of Hibiscus, to investigate the formation of a semi-ordered diffraction grating on the petal surface. We show that regulating both cuticle production and epidermal cell growth is insufficient to determine the type of cuticular pattern produced. Instead, the chemical composition of the cuticle plays a crucial role in restricting the formation of diffraction gratings to the pigmented region of the petal. This suggests that buckling, driven by spatiotemporal regulation of cuticle chemistry, could pattern the petal surface at the nanoscale. •Petal texture is not exclusively set by cuticle production rate and cell expansion•Color production through ordered striations in Hibiscus depends on cuticle chemistry•Interfering with cuticular chemical composition impairs regular striation formation•Spatial regulation of cuticle chemistry could restrict buckling to the petal base Microscopic striations on petal surfaces can interfere with light and produce structural color. Combining genetic and mechanical manipulations with chemical analysis and theoretical modeling, Moyroud et al. show that to specify where, when, and how striations emerge, Hibiscus trionum flowers regulate the chemical composition of their cuticle.