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B427: The evolution of cellular diversity in the multicellular green lineage (Lead Supervisor: Beverley Glover, Plant Sciences)

Supervisor: Beverley Glover (Plant Sciences)  

Importance of the area of research:

Plants have several different types of cells, defined by their morphology, chemistry and function. This project is about the evolution of the ability to make all of these different cell types.

The transition from single-celled life to multicellular life depended on the evolution of new cell types, arising through various different forms of cellular specialisation. To achieve different cell types within an organism and ensure that they are correctly distributed in both space and time requires the integration of signals and co-ordinated regulation of gene expression. Proteins called transcription factors are therefore of central importance to the generation of cellular specialisation, because they activate the expression of cascades of downstream genes. Some transcription factors act in multi-component complexes, which means that the same transcription factor protein can be used repeatedly, with the outcome (the genes it activates) determined by which other transcription factors act in concert with it. This proposal focuses on the evolution of a complex of transcription factors that underpins the evolution of plant epidermal cellular diversity and explains the success of land plants.

Project summary:

An enormous range of cellular outcomes in the epidermis of plants are specified by a single transcriptional complex, the MBW complex, which comprises a WDR protein, one of a few bHLH proteins, and one of many MYB proteins. Our aim in this proposal is to explore the evolutionary history of this complex, to determine how it has contributed to the evolution of cellular diversity. Defining the evolutionary history of the MBW complex will allow us to understand how plants can use a single complex to flexibly specify such a wide range of epidermal structures, and allow us to link the evolutionary history of the complex to the evolution of multiple cell types and the radiation of plant lineages.

What the student will do:

This project will combine phylogenetic approaches to understanding gene family evolution with molecular genetic tests of gene function in diverse plant lineages. During the project you will use:

1. Phylogenetic reconstruction of the WDR, bHLH and MYB protein subfamilies that contribute to the complex, to develop hypotheses about how early the complex might have evolved.

2. Exploration of whether the protein domains essential for complex formation in the 3 protein families are conserved across the phylogenies, and assess whether we can determine when this complex evolved. In vitro tests of protein-protein interaction using yeast-2-hybrid analysis.

3. Using the phylogenies produced in 1 we will explore whether diversity in complex function arose in particular plant groups by lineage-specific radiations in certain gene families.

4. The hypotheses produced from these analyses will be tested by selecting genes from key phylogenetic positions and assessing the extent to which they can complement Arabidopsis mutants in the same component of the complex.

5. You will also explore endogenous function of module members at key phylogenetic positions by expression analyses and transgenic approaches.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

1.Ramsay, N. and Glover, B.J.  2005. The MYB/MYC/bHLH complex and the evolution of cellular diversity. Trends in Plant Science 10, 63-70.

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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