Brachypodium distachyon as a genetic model pathosystem to study resistance against fungal pathogens of small grain cereals

Peraldi, Antoine (2012) Brachypodium distachyon as a genetic model pathosystem to study resistance against fungal pathogens of small grain cereals. Doctoral thesis, University of East Anglia.

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Fusarium head blight (FHB) and other Fusarium diseases of wheat and other small-grain
cereals cause yield reduction and grain contamination with harmful mycotoxins, mainly
deoxynivalenol (DON). Little is known about the mechanistic basis of resistance to
Fusarium in cereals due to the large, polyploid and unsequenced genome of wheat. Host
ethylene (ET) signalling was previously shown to be a factor of susceptibility to FHB.
Chapter 2 uses wheat EMS mutant lines characterized for altered senescence to test for a
relationship between ET-sensitivity, senescence and resistance to FHB. Candidate mutant
lines displaying high level of resistance to FHB were identified and resistance was
associated with delayed senescence, reduced ET-sensitivity, or developmental delay.
Brachypodium distachyon (Bd) has the potential to serve as a model pathosystem relevant
to small-grain cereals. Chapter 3 provides evidence of compatibility between Bd and the
main causal agents of FHB and shows that symptom development mirrors closely that in
wheat. Natural variation in disease resistance exists among Bd accessions and a novel route
for initial infection is suggested. Bd is also compatible with other important pathogens of
small-grain cereals causing ramularia, eyespot and take-all diseases. In Chapter 4, a
preliminary study of Bd T-DNA mutant lines altered in phytohormone biosynthesis or
response investigates alteration of Fusarium resistance. Mutation of the main
brassinosteroid (BR) receptor (BRI1) was characterized and validated. Other mutants
defective in auxin or ET responsiveness and jasmonic acid (JA) biosynthesis were
investigated. Results suggest that JA and BRI1 promote disease susceptibility. Finally,
Chapter 5 uses a chemical and genetic approach to investigate the mechanisms of DON
phytotoxicity using the Bd root system. Effects induced by the mycotoxin are compared
with BRs, inhibitors of protein synthesis and compounds altering BR biosynthesis or
signalling. Results suggest that DON may disrupt host BR homeostasis to promote disease

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Users 2259 not found.
Date Deposited: 06 Mar 2014 12:50
Last Modified: 06 Mar 2014 12:50

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