Evolutionary genetics of flower colour variation in Antirrhinum

Elis, Mabon (2018) Evolutionary genetics of flower colour variation in Antirrhinum. Doctoral thesis, University of East Anglia.

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Abstract

Phenotypic differences between species and populations can reveal much about how they have adapted and responded to a complex set of environmental cues. Studies have shown that genetic control of some traits is centralised to single genomic regions, while others are regulated at many unlinked loci dispersed throughout the genome. One trait that shows an enormous degree of variation between plant species is flower colour, and its tractability makes it an ideal trait for studying genetic differences underlying species differentiation. Antirrhinum majus has long been used as a model for studying floral traits, including colour. The 20-30 wild Antirrhinum species use diverse patterns on their flowers, formed by producing and accumulating magenta anthocyanins and yellow aurones in different tissues, to attract pollinators. In this project, I sought to genetically map flower colour phenotypes to the Antirrhinum genome. Several Antirrhinum species were crossed to A. majus to generate segregating populations. I used a combination of bulked segregant analysis, individual genotyping of segregating populations and analysis of genome sequences from wild accessions to test whether genes governing each colour trait were concentrated at particular loci or dispersed across many chromosomes. I found that variation in magenta not previously characterised maps to the known ROSEA-ELUTA (ROS-EL) locus where transcription factors regulating anthocyanin production are encoded. Yellow phenotypes from three species mapped to chromosome 2, where there is reduced recombination between A. majus and many wild species, and where an aurone biosynthetic enzyme is encoded. However, there appear to be some additional modifiers of flower colour in these species, not linked to the ROS-EL and chromosome 2 loci. These results fit neither the central- nor dispersed-control models of genetic control, but rather an intermediate hypothesis – that flower colour can be changed by selection acting on a modest number of loci spread throughout the genome.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Gillian Aldus
Date Deposited: 15 Jan 2019 10:49
Last Modified: 15 Jan 2019 10:49
URI: https://ueaeprints.uea.ac.uk/id/eprint/69572
DOI:

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