Using wheat genetic resources to identify novel sources of resistance and susceptibility to FHB

Badgami, Roshani (2024) Using wheat genetic resources to identify novel sources of resistance and susceptibility to FHB. Doctoral thesis, University of East Anglia.

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Abstract

Fusarium Head Blight (FHB) is a devastating fungal disease of wheat, causing premature spike bleaching and accumulation of mycotoxins such as deoxynivalenol (DON) in the grain. Resistance to pathogen spread can be achieved by removing susceptibility loci and/or introgressing resistance loci from the wider gene pool. Previous studies reported major FHB susceptibility loci on chromosome 4DS and 7AS and a major FHB resistance locus on chromosome 3G from Triticum timopheevii. Identifying the underlying genes conferring the FHB response for these loci may provide new sources of FHB resistance.

In the present study, a deletion mapping approach was conducted using a Paragon gamma-irradiated deletion population to refine the susceptibility loci on chromosome 4DS and 7AS. No single region was found to confer the major FHB response associated with either locus. T. timopheevii recombinant inbred populations were used to refine the chr3G FHB resistance locus and determine whether resistance is related to DON response. The chr3G FHB resistance locus was shown to function against DON and refined to a 46.9 kbp interval. Sequence comparisons of this region between the T. timopheevii parents identified three candidate genes with gene expression during spike development. This interval has high homology to Fhb1, the most highly studied FHB resistance in wheat. The Watkins landraces and wild relatives were screened for the presence of Fhb1. Resistant Fhb1 haplotypes were found in geographically diverse Watkins accessions and T. timopheevii accessions. Subsequent protein sequence comparisons between the T. timopheevii and Fhb1 alleles revealed that the most plausible candidate gene was an E3 ubiquitin ligase where the loss of the RING domain was predicted to be responsible for conferring FHB resistance. This study shows that Fhb1 may have originated from the introgression of a T. timopheevii relative into hexaploid wheat before the divergence of European and Asian lineages.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	02 Jun 2025 10:44
Last Modified:	02 Jun 2025 10:44
URI:	https://ueaeprints.uea.ac.uk/id/eprint/99377
DOI:

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