Genome size divergence in the evolution of flowering plants

Theme: Biodiversity & Ecology

Primary Supervisor:

Andrew Leitch

School of Biological and Chemical Sciences, QMUL

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Secondary Supervisor:

Ilia Leitch

Comparative Plant and Fungal Biology, KEW

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Additional Supervisor(s):

Project Description:

Flowering plants have an immense 2,400-fold range in genome sizes, a range that is larger than any other comparable eukaryotic group (Leitch & Leitch, 2012). Several features of angiosperm divergence explain this range in genome size, these being: (1) the high frequency of underlying polyploidy (e.g. the diploid model plant Arabidopsis thaliana may in fact be at least 48-ploid) and (2) the amplification of repetitive DNA sequences, which are typically abundant in plant genomes (Leitch & Leitch, 2008). Despite these processes that amplify DNA in plant evolution, most species, in fact, have small genome sizes, suggestive of mechanisms that result in “genome downsizing”. It has been proposed that following polyploidy, genomes are honed-back to smaller sizes by the action of selection and/or genetic drift (Dodsworth et al., 2015a,b). However the mechanisms underpinning these evolutionary pressures, and the effects of drift and/or selection acting on genome sizes are little understood. This studentship will address this deficiency in knowledge, leading to a clearer understanding of genome dynamics across the diversity of plants overall. The work will also provide training in a range of skills relevant to the fields of agricultural and environmental sciences, bioinformatics, molecular and cell biology.

Dodsworth et al. 2015a. J Linn Soc 8: 161-175

Dodsworth et al. 2015b. Curr Op Gen Develop 35: 73-78.

Leitch AR, Leitch IJ. 2008. Science 320: 481-483.

Leitch AR, Leitch IJ. 2012. New Phyt 194: 629-646.

Policy Impact of Research:

1. Environmental and Conservation Organizations

Our genome size data can be integrated to plant trait databases leading to new understanding of biodiversity. Conservation organizations can then prioritize species and habitats at greatest risk.

2. Agricultural Companies

A solution to increase yield to meet our needs is to exploit genome sequencing and plant breeding involving wild species, requiring genome size estimations

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