Identifying genes underlying Fusarium and mycotoxin susceptibility in Brachypodium distachyon

Bankes-Jones, Elizabeth (2021) Identifying genes underlying Fusarium and mycotoxin susceptibility in Brachypodium distachyon. Doctoral thesis, University of East Anglia.

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Abstract

Fusarium head blight (FHB) is a widespread fungal disease of temperate, small-grain cereals. Infection leads to reduced yield and mycotoxin accumulation in grain. Chemical controls have limited effect and genetic resistances are typically quantitative and environmentally sensitive. Brachypodium distachyon (Bd) has been demonstrated as a model for cereal-Fusarium interactions and is a powerful genetic tool due to having a small, diploid genome, high recombination rate and a pan-genome sequence of 54 diverse accessions.

These Bd accessions were characterised for variation in susceptibility to FHB, flowering time, height and trichomes. A recombinant inbred line (RIL) population, ABR6 x Bd21, was characterised for susceptibility to FHB and lemma trichome phenotype. A coincident QTL for FHB resistance and absence of trichomes was identified on Bd chromosome four. It was hypothesised that trichome basal cells are exploited as points of infection for Fusarium species. Fine mapping refined the position of the trichome trait to a physical region containing five annotated genes in Bd21. Expression and sequence analysis identified an ATP-dependent CLP protease as the best candidate gene. CRISPR mutagenesis was unsuccessful, without which it was not possible to determine whether the relationship between FHB and trichomes is causative or pleiotropic.

Concentration dependent root elongation and inhibition in response to deoxynivalenol (DON) had been previously observed in Bd. DON sensitivity of Bd accessions was characterised using root assays. A novel root branching phenotype was identified in accession Bd2-3, and the Bd2-3 x Bd21 RIL population characterised at two DON concentrations. A region on Bd chromosome 1 was identified to be associated with DON sensitivity, refined to a region of 56 genes using bulked segregant analysis and RNAseq among which four were differentially DON-responsive between the two accessions indicating that one or more may be responsible for the observed difference in DON response.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 13 Oct 2021 13:10
Last Modified: 13 Oct 2021 13:10
URI: https://ueaeprints.uea.ac.uk/id/eprint/81692
DOI:

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