Adaptive metabolic gene clusters as toolkits for chemical innovation: Investigation of the origin of the avenacin gene cluster for synthesis of defense compounds in oats

Chu, Hoi Yee (2013) Adaptive metabolic gene clusters as toolkits for chemical innovation: Investigation of the origin of the avenacin gene cluster for synthesis of defense compounds in oats. Doctoral thesis, University of East Anglia.

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Abstract

Operon-like gene clusters are functional cassettes of physically linked and
non-homologous genes involved in the same pathway. To date, 20 such plant
gene clusters have been discovered, all of which are involved in specialised
metabolism. Plant gene clusters raise interesting biological questions about their
importance and the drivers behind their formation. This thesis describes the
investigation of the evolution of the avenacin gene cluster, discovered in the
diploid oat Avena strigosa S75, via wet-bench experiments and bioinformatic
analyses, commencing with the general introduction (Chapter 1).
Chapter 2 to 4 describe the survey on the avenacin production, expression
pattern and phylogeny of the �ve characterized avenacin biosynthetic (Sad)
genes within Aveninae, focusing on Avena L. The genomes of all Avena spp.
investigated, including the avenacin de�cient A. longiglumis, possess the �ve Sad
gene homologues. The expression pattern of the Sad gene homolgoues vary in a
genome-type dependent manner that it is root-speci�c amongst A genome oats.
However, the C genome oats show root and leaf expressions, contributed by
di�erentially expressed Sad gene duplicates.
Chapter 5 and 6 describe the molecular evolutionary analysis of the �ve gene
families implicated in triterpene biosynthesis: oxidosqualene cyclases,
cytochromes P450 51s, Clade 1A serine carboxypeptidase-like acyltransferases,
Class I O-methyl transferases and Group L glycosyltransferases in monocots.
Phylogenetics analyses show that these gene families evolve via
duplication-neofunctionalisation, facilitated by gene GC content and exon-intron
structures changes under purifying selection on amino acid sequences. Syntenic
study of the triterpene biosynthetic gene families reveals the ancestral triterpene
biosynthetic OSC/CYP51 gene pair found in the �-WGD event.
Finally, the evolutionary model of the avenacin biosynthesis and the potential
applications of the knowledge of gene clustering in systematic and synthetic
biology are descibed in Chapter 7.

*[N.B.: Additional files were attached to this thesis at the time of its submission. Please refer to the author for further details.]

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Mia Reeves
Date Deposited: 11 Mar 2014 15:04
Last Modified: 11 Mar 2014 15:04
URI: https://ueaeprints.uea.ac.uk/id/eprint/48080
DOI:

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