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Glover Group: How to spot a daisy (evolution and development of petal spots)

NERC / GFC / OTHER

Supervisor: Beverley Glover (Plant Sciences)

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Importance of the area of research concerned:

This project is part of our efforts to understand the diversity of interactions between plants and their pollinators. We are interested in these interactions because they underpin the species radiation of the angiosperms, and are an essential component of understanding the diversity and evolution of life on earth. A good understanding of plant-pollinator interaction networks is crucial for developing strategies for the conservation of biodiversity, and is also important in considering global food security.

Project summary:

This project aims to understand the evolution and development of dark petal spots on flowers. Many daisies produce dark spots on their ray florets. Gorteria diffusa produces raised dark spots at the base of some (usually 1–3) ray florets. Pollination studies have demonstrated that these structures are mimics of small bee-flies (Megapalpus capensis) that are attracted to the petal spots and show an aggregating, feeding or mating response. The Gorteria petal spots are complex, consisting of three different cell types and localized anthocyanin deposition. In the centre of the spot is a white highlight patch, containing no anthocyanin, and in a horseshoe-shape around the entire spot are large papillae, which give the spot its three-dimensional appearance. In this project you will consider the development of the Gorteria petal spot and the evolution of this developmental programme.

What will the student do?:

  1. We have already identified the transcriptional regulator that activates anthocyanin synthesis in the petal spots. Its expression pattern is spatially restricted to the spot region. Therefore you will isolate the master genes controlling spot identity by identifying the transcriptional regulators that activate its expression,.
  2. Gorteria diffusa contains at least 12 variants, differing greatly in spot characteristics. These "morphotypes" are found as semi-discrete populations within the narrow endemic range Gorteria occupies in South Africa. The petal spots of the different morphotypes vary in number; number of white highlights within the spot; extent and position of the papillae; and amount of anthocyanin. You will study how the petal spot genes function in each of these morphotypes by comparing sequences and expression patterns, and using transgenic approaches with selected genes.
  3. Many closely related daisies found in the same habitat also produce petal spots, although of a much simpler type. You will explore the evolution of these in a phylogenetic context by assessing whether the Gorteria petal spot genes play a role in spot development in other species.

References:

  • Thomas, M., Rudall, P., Ellis, A., Savolainen, V. & Glover, B.J. (2009) Development of a complex floral trait: the pollinator-attracting petal spots of the beetle daisy, Gorteria diffusa (Asteraceae). American Journal of Botany 96, 2184-2196.
  • Ellis, A., Brockington, S., de Jager, M., Mellers, G., Walker, R. & Glover, B.J. (2014) Floral trait variation and integration as a function of sexual deception in Gorteria diffusa. Philosophical Transactions of the Royal Society Series B 369, 20130563.

Applying: To the Cambridge NERC C-CLEAR DTP programme: https://nercdtp.esc.cam.ac.uk/

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