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Cereal Killers: Understanding How Fungi Infect Plants
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Nick ¡Talbot
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@talbotlabexeter http://www.exeter.ac.uk/nicktalbot/ New Fellows Seminar, The Royal Society, London July 10th 2014
Cereal Killers: Understanding How Fungi Infect Plants Nick - - PowerPoint PPT Presentation
Cereal Killers: Understanding How Fungi Infect Plants Nick - - PowerPoint PPT Presentation
@talbotlabexeter http://www.exeter.ac.uk/nicktalbot/ Cereal Killers: Understanding How Fungi Infect Plants Nick Talbot New Fellows Seminar, The Royal Society, London July 10 th 2014 Rice blast symptoms in Hunan Province, China -
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Neck ¡Blast ¡
Hunan, ¡China ¡ October ¡2007 ¡
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Conidium Spore tip mucilage Germ tube Melanin-lined appressorium cell wall Autophagic cell death Primary invasive hyphae Penetration peg Conidiophore Tissue colonisation Eruption
Life ¡Cycle ¡of ¡Magnaporthe ¡oryzae ¡
How do appressoria form? How do appressoria function? How is plant tissue colonized? How is host immunity suppressed ?
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Conidium Spore tip mucilage Germ tube Melanin-lined appressorium cell wall Autophagic cell death Primary invasive hyphae Penetration peg Conidiophore Tissue colonisation Eruption
Life ¡Cycle ¡of ¡Magnaporthe ¡oryzae ¡
How do appressoria form?
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Conidia ¡of ¡Magnaporthe ¡oryzae ¡
10 µm
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5 µm Appressorium ¡forma0on ¡ in ¡Magnaporthe ¡oryzae ¡
De Jong et al., 1997 Nature 389:244-5 Veneault-Fourrey et al. 2006 Science 31: 580-3 Kershaw & Talbot, 2009 PNAS 106:15967-72
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Autophagy is required for nuclear degeneration, collapse of the conidium and plant infection
WT Δatg8 WT Δatg8 Veneault-Fourrey et al. 2006 Science 31: 580-3
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Conidium Spore tip mucilage Germ tube Melanin-lined appressorium cell wall Autophagic cell death Primary invasive hyphae Penetration peg Conidiophore Tissue colonisation Eruption
Life ¡Cycle ¡of ¡Magnaporthe ¡oryzae ¡
How do appressoria function?
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How is cellular asymmetry generated in an appressorium?
Bourett and Howard, 1990
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An F-actin network forms around the appressorium pore
LifeAct-RFP
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Septins control cell shape in filamentous fungi
Septins form heterooligomers
Localize at mother-bud neck
Septin mutants have cell separation defects
Wild type cdc11ts
Septins can change cell shape
Spilliotis and Gladfelter 2011
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Sep3-GFP
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Septin ring around appressorial pore colocalizes with an actin network
Lifeact Sep3
10 µm
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Septins organise a toroidal F-actin network at the appressorium pore that is essential for plant infection
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The ¡role ¡of ¡sep>ns ¡in ¡appressorium-‑mediated ¡cu>cle ¡ rupture ¡
Dagdas et al. 2012 Science 336:1590-95
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Conidium Spore tip mucilage Germ tube Melanin-lined appressorium cell wall Autophagic cell death Primary invasive hyphae Penetration peg Conidiophore Tissue colonisation Eruption
Life ¡Cycle ¡of ¡Magnaporthe ¡oryzae ¡
How is plant tissue colonized? How is host immunity suppressed ?
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Merge ¡ Plant ¡membrane ¡ Fungal ¡cytoplasm ¡
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Th ¡ PtoxA-‑tdTomato ¡ L06b ¡ ¡
Invading ¡hyphae ¡are ¡surrounded ¡by ¡the ¡host ¡plant ¡plasma ¡ membrane ¡
Mentlak et al. 2012 Plant Cell 24: 322-35
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1 180
LysM LysM
Effectors suppress plant immunity
- Slp1 accumulates in the apoplast
- Only expressed in planta
- Two LysM domains
- Binds chitin with high affinity
- Competitively inhibits CEBiP PRR
- Necessary for virulence
Mentlak et al., 2012 Plant Cell 24:322-35
- Slp1 is glycosylated
- N-Glycosylation of Slp1 is essential for
activity
Chen et al., 2014 Plant Cell online early
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Many fungal pathogens develop specialized cells to infect plants called appressoria In rice blast disease, appressoria develop enormous pressure and use physical force to rupture plant cuticle Appressorium development is subject to cell cycle regulation and occurs in response to physical cues from the host surface Appressorium turgor generation is due to intracellular glycerol accumulation Septin-dependent re-modeling of the actin cytoskeleton is required for appressorium function Host cells remain intact as they are colonised by the fungus and plant immunity is actively suppressed
Summary
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Yasin Dagdas Lauren Ryder Wasin Sakulkoo Xia Yan Magdalena Urdiroz Darren Soanes Mick Kershaw Miriam Oses-Ruiz Yogesh Gupta George Littlejohn Tom Mentlak
Gero Steinberg
Halpin ¡ ¡Trust ¡
Anotida Madzvamuse Chandrasekhar Venkataraman Vanessa Styles University of Sussex Anastasia Desyatova Joseph Turner Richard Wilson University of Nebraska Barbara Valent Martha Giraldo Kansas State University Hiromasa Saitoh Ryohei Terauchi Iwate Rice Biotechnology Center You-Liang Peng China Agricultural University, Beijing JinRong Xu Purdue University Bart Thomma Wageningen University Naoto Shibuya Meiji University