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Title: Investigating the regulation of host tissue colonisation by the rice blast fungus Magnaporthe oryzae
Author: Sakulkoo, Wasin
ISNI:       0000 0004 5992 5876
Awarding Body: University of Exeter
Current Institution: University of Exeter
Date of Award: 2016
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The filamentous fungus Magnaporthe oryzae is a devastating pathogen of cultivated rice. M. oryzae elaborates a pressurized dome-shaped infection structure, called the appressorium, which physically ruptures the cuticle and gains entry into host tissue. Intracellular invasive hyphae invade neighbouring host cells through plasmodesmata. The Pmk1 MAPK cascade is well known for its roles in regulating the formation and function of the appressorium. Interestingly, ∆pmk1 mutants cannot infect host plant tissue through wounds, suggesting a role in invasive growth. Here, I define biological functions of the Pmk1 MAPK at various stages of the life cycle, by using a controllable version of Pmk1 that is specifically inhibited by a cell-permeable compound without disturbing other wild-type kinases. The Pmk1 MAPK signalling regulates morphogenesis of narrow invasive hyphae traversing the host cell wall, and modulates production of several putative secreted effectors, providing a direct link between the signalling cascade and effector-driven host immune suppression. These results indicate that the Pmk1 pathway is a central regulator of infection-related development necessary for many stages of plant infection including appressorium development, plant penetration, and importantly tissue colonisation. I also report the role of cell cycle progression in the development of plant infection structure. By using two novel conditional mutants that arrest in S and G2 phases, I defined that S-phase progression is crucial for appressorium-mediated plant penetration.
Supervisor: Talbot, Nicholas J. Sponsor: Halpin Trust
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: pathogen ; rice ; fungi ; signalling ; cell cycle ; MAPK ; Pyricularia ; effector