EXPLORING THE GENETIC DIVERSITY IN WHEAT FOR RESISTANCE TO SEPTORIA TRITICI BLOTCH

Hafeez, Amber (2022) EXPLORING THE GENETIC DIVERSITY IN WHEAT FOR RESISTANCE TO SEPTORIA TRITICI BLOTCH. Doctoral thesis, University of East Anglia.

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Abstract

Septoria tritici blotch (STB) is a foliar disease of wheat caused by the fungal pathogen Zymoseptoria tritici and is the third-most impactful wheat disease worldwide, due in part to the pathogen’s widespread resistance to fungicides. It is therefore vital that more sources of host resistance are characterised and deployed.

Wild species contain multitudes of unexploited genetic variation, without the genetic bottlenecks and artificial selection pressures imposed upon crops. The D-genome progenitor of bread wheat, Aegilops tauschii, has shown near immunity to STB, yet this interaction is scarcely studied and little understood. Landraces are another valuable resource from which resistances that have been lost on the road to developing elite cultivars could be rediscovered. An example is the highly genetically and geographically diverse Watkins collection of pre-Green Revolution wheat landraces.

Association genetics was employed to investigate the genetic basis of resistance to Z. tritici in Watkins landraces by using whole-genome shotgun sequences for a set of 300 accessions. This led to the rediscovery of Stb6 conferring resistance to the Z. tritici isolate IPO323. Subsequently, a candidate gene conferring resistance to IPO88004 and encoding a serine/threonine protein kinase was discovered on chromosome 6A, likely the previously-designated gene Stb15. The haplotype diversity of these genes in the panel was explored. A region on chromosome 4D associated with damage responses to IPO90012 was also investigated. Additionally, these methods were applied to an Aegilops tauschii diversity panel. Although the high prevalence of incompatible interactions limited the efficacy of this approach, several loci associated with necrosis responses were identified.

The identification of the third gene in the Stb canon, Stb15, provides valuable insights into the functional genetic architecture of Z. tritici resistance in wheat. Together, these results form a case study demonstrating both the power and limitations of association genetics for STB resistance gene discovery.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Kitty Laine
Date Deposited:	07 Dec 2022 16:57
Last Modified:	07 Dec 2022 16:57
URI:	https://ueaeprints.uea.ac.uk/id/eprint/89990
DOI:

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