Trichomes are widespread in plants and develop from surface cells on different tissues1. They have many forms and functions, from defensive spines to physical barriers that trap layers of air to insulate against desiccation, but there is growing evidence that trichomes can also have developmental roles in regulating flower structure2,3. We report here that the trichomes on petals of cotton, Gossypium hirsutum L., are essential for correct flower bud shape through a mechanical entanglement of the trichomes on adjacent petals that anchor the edges to counter the opposing force generated by asymmetric expansion of overlapping petals. Silencing a master regulator of petal trichomes, GhMYB-MIXTA-Like10 (GhMYBML10), by RNA interference (RNAi) suppressed petal trichome growth and resulted in flower buds forming into abnormal corkscrew shapes that exposed developing anthers and stigmas to desiccation damage. Artificially gluing petal edges together could partially restore correct bud shape and fertility. Such petal ‘Velcro’ is present in other Malvaceae and perhaps more broadly in other plant families, although it is not ubiquitous. This mechanism for physical association between separate organs to regulate flower shape and function is different from the usual organ shape control4 exerted through cell-to-cell communication and differential cell expansion within floral tissues5,6.
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We thank E. Johnston, H. Martin and J. Radik for technical assistance, Z. Stachurski (Australian National University) for assistance with biomechanical testing and M. Talbot for assistance with SEM. The authors acknowledge the Black Mountain Bioimaging Centre for instrumentation, training and technical support. This work was supported by funding from the Monsanto Company and Cotton Breeding Australia (a joint venture between CSIRO and Cotton Seed Distributors).
The authors declare no competing financial interests.
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Tan, J., Walford, SA., Dennis, E. et al. Trichomes control flower bud shape by linking together young petals. Nature Plants 2, 16093 (2016). https://doi.org/10.1038/nplants.2016.93
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