SEPBLAST: Determining the molecular basis of septin-dependent plant infection by the blast fungus Magnaporthe oryzae
Lead Research Organisation:
University of East Anglia
Department Name: Sainsbury Laboratory
Abstract
The major aim of this research project is to understand how morphogenetic proteins called septins condition the ability of a pathogenic fungus to cause disease within a plant. Plant pathogenic fungi have evolved specialised infection structures to enter their hosts. The devastating blast fungus Magnaporthe oryzae infects rice plants using a pressurised infection cell called an appressorium to breach the tough outer layer of plants. Once inside plant tissue, the fungus then develops a second type of infection structure, called a transpressorium, which it uses to move from one rice cell to the next. Recent evidence has shown that heteromeric septin complexes are necessary for the function of both appressoria and transpressoria. This ambitious research project will define the molecular basis of septin recruitment, organisation and function within these infection structures. I propose to evaluate the membrane curvature dependency of septin aggregation and then identify upstream components that regulate septin recruitment. A comprehensive septin interactome will be defined for both cell types using proteomic analysis and proximity labelling methods, during a time series of appressorium and transpressorium development. In this way, novel septin interactors will be identified and functionally characterised. In parallel, phosphoproteomic analysis will be used to investigate the specific phosphorylation events necessary for septin assembly and to identify the corresponding signalling pathways. Using a combination of forward genetic screens, targeted gene editing, proteomic analysis and live cell imaging, the project will test the hypothesis that septin complexes act as major organising centres within fungal invasive cells, required for the focused deployment of polarity and virulence determinants to enable invasive growth by fungal infection cells.
Organisations
People |
ORCID iD |
Nicholas Talbot (Principal Investigator) |
Publications

Eisermann I
(2024)
Septin-dependent invasive growth by the rice blast fungus Magnaporthe oryzae.
in Journal of plant diseases and protection : scientific journal of the German Phytomedical Society (DPG)

Eisermann I
(2023)
The emerging role of septins in fungal pathogenesis.
in Cytoskeleton (Hoboken, N.J.)
Description | We have addressed the first objective of SEPBLAST by investigating the response of the core septins of Magnaporthe oryzae to membrane curvature. Using a bead assay that provides a plasma membrane bilayer at specific levels of curvature, in collaboration with Dr Amy Gladfelter at Duke University, we have recently established the precise level of micron level curvature which stimulates heteropolymer formation on plasma membrane bilayers. We have begun to quantify the aggregation kinetics of M. oryzae septin aggregation and use this to define the specific domains associated with membrane interactions. We have addressed the second major aim of SEPBLAST by defining the septin interactome during appressorium morphogenesis by the rice blast fungus. This has involved co-immuno-precipitation mass spectrometry to define interactors of Sep3, Sep4, Sep5 and Sep 6 during a time-course of appressorium development. We have validated interactions by high throughput yeast two hybrid analysis and structural modelling. Key septin interactors are being functionally characterised to define their functions in polarised growth regulation and pathogenesis. We are also working toward a structural understanding of septin aggregation during appressorium morphogenesis. In collaboration with Richard Garratt's laboratory (University of São Paulo, Brazil), we have generated an X-ray crystal structure of a Sep6-Sep5 tetramer at 1.57 Å and a Cryo-EM tetramer structure at 3.44 Å. We also have a higher resolution Sep5-Sep6 dimer cryo-EM structure at 2.77 Å. Most recently, the full Sep3, Sep4, Sep5, Sep6 hetero-octamer has been analyzed at the Diamond Facility and we are working on the entire structure. In parallel, we have begun to carry out cryo-electron tomography in collaboration with Dr Juan Carlos de la Concepcion in GMI-Vienna of septin polymers within appressoria that we have been able to fom on grids. Our aim is to define the structure of the septin ring complex in whole cells and thereby define its precise role during appressorium-mediated plant infection. We have furthermore developed a novel procedure to measure membrane tension during appressorium turgor generation in collaboration with Joris Sprakel (Wageningen University, Netherlands). We are using this quantitative fluorescence lifetime imaging microscopy (FLIM) method to measure appressorium turgor generation and its genetic control. |
Exploitation Route | The outcomes have considerable potential in the control of plant diseases by fungal pathogens and design of new anti-fungal strategies. This will be ocme more clear as the work progresses. |
Sectors | Agriculture Food and Drink Pharmaceuticals and Medical Biotechnology |
Description | Invited Speaker at the 52nd SBBq Annual Meeting in São Paulo, Brazil |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Talk entitled: "Investigating the cell biology of plant infection by Magnaporthe oryzae, causal agent of Rice Blast and Wheat Brusone disease" |
Year(s) Of Engagement Activity | 2023 |
Description | Keynote lecture at the Reinhardsbrunn Symposium in Friedrichrhoda, Germany |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Talk entitled: "Can a knowledge of septin-dependent plant infection by the blast fungus Magnaporthe oryzae be used for disease control?" |
Year(s) Of Engagement Activity | 2023 |
Description | invited speaker at the 12th International Congress of Plant Pathology (ICPP) in Lyon, France |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Talk title: Functional analysis of the mep effector gene repetoire of the blast fungus Magnaporthe oryzae |
Year(s) Of Engagement Activity | 2023 |
Description | invited speaker at the Institute of Plant and Microbial Biology symposium, Academia Sinica, Taipei, Taiwan |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | talk title: Can a knowledge of septin-dependent plant infection by the blast fungus Magnaporthe oryzae be used for disease control? |
Year(s) Of Engagement Activity | 2023 |