Genome evolution of a pandemic lineage of the wheat blast pathogen

Malmgren, Angus George Gunnar (2025) Genome evolution of a pandemic lineage of the wheat blast pathogen. Masters thesis, University of East Anglia.

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Abstract

Blast fungus, Magnaporthe oryzae, is a plant pathogen composed of multiple host-specific lineages and causes significant damage to cereal crops. The Triticum lineage is responsible for the highly damaging wheat blast disease prevalent within South America, which was identified in 1985. Whilst originally confined to South America, since 2016, a clonal lineage infecting on wheat has been found to have also spread to Zambia and Bangladesh, and was termed the B71 lineage after the South American B71 isolate which forms part of the group. To aid understanding of the adaptive evolution in this lineage, genomic segments in Zambian and Bangladeshi isolates which were not conserved with the B71 isolate were identified, and subsequently used to identify population-specific effector candidates. Two of these candidate effectors were investigated further: Art1_WB_ZM identified in the Zambian population, and APiasL3 identified in the Bangladeshi population. APiasL3 is notable for being present in the mini-chromosome in Bangladeshi isolates in a region which has also been integrated into the core genome in one isolate. Following attempted generation of effector deletion transformants, leaf drop infection assays using Art1_WB_ZM-deletion transformants did not demonstrate altered ability to infect on different hosts compared to the wild type. Structures for both candidates were predicted using AlphaFold, and patterns of conserved residues were identified in the APiasL3 candidate with the family of proteins it belongs to, in addition to indications of positive selection on certain APiasL3 residues. Improving understanding of the effector makeup of blast fungus lineages could aid response strategy development and inform management practices to limit further disease spread.

Item Type:	Thesis (Masters)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	02 Dec 2025 09:49
Last Modified:	02 Dec 2025 09:49
URI:	https://ueaeprints.uea.ac.uk/id/eprint/101176
DOI:

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