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 - 2007

Neck ¡Blast ¡ Hunan, ¡China ¡ October ¡2007 ¡

Life ¡Cycle ¡of ¡ Magnaporthe ¡oryzae ¡ Conidium Conidiophore Spore tip mucilage Eruption How is host immunity How do appressoria suppressed ? form? Germ tube Tissue colonisation How is plant tissue Autophagic colonized? cell death How do appressoria function? Melanin-lined appressorium cell wall Primary invasive hyphae Penetration peg

Life ¡Cycle ¡of ¡ Magnaporthe ¡oryzae ¡ Conidium Conidiophore Spore tip mucilage Eruption How do appressoria form? Germ tube Tissue colonisation Autophagic cell death Melanin-lined appressorium cell wall Primary invasive hyphae Penetration peg

Conidia ¡of ¡ Magnaporthe ¡oryzae ¡ 10 µ m

Appressorium ¡forma0on ¡ in ¡ Magnaporthe ¡oryzae ¡ 5 µ m 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

Autophagy is required for nuclear degeneration, collapse of the conidium and plant infection Δ atg8 WT Δ atg8 WT Veneault-Fourrey et al. 2006 Science 31: 580-3 ¡

Life ¡Cycle ¡of ¡ Magnaporthe ¡oryzae ¡ Conidium Conidiophore Spore tip mucilage Eruption Germ tube Tissue colonisation Autophagic cell death How do appressoria function? Melanin-lined appressorium cell wall Primary invasive hyphae Penetration peg

How is cellular asymmetry generated in an appressorium? Bourett and Howard, 1990

An F-actin network forms around the appressorium pore LifeAct-RFP

Septins control cell shape in filamentous fungi Septin mutants have cell separation Septins form heterooligomers defects cdc11 ts Wild type Septins can change cell shape Localize at mother-bud neck Spilliotis and Gladfelter 2011

Sep3-GFP

Septin ring around appressorial pore colocalizes with an actin network Lifeact Sep3 10 µm

Septins organise a toroidal F-actin network at the appressorium pore that is essential for plant infection

The ¡role ¡of ¡sep>ns ¡in ¡appressorium-­‑mediated ¡cu>cle ¡ rupture ¡ Dagdas et al. 2012 Science 336:1590-95

Life ¡Cycle ¡of ¡ Magnaporthe ¡oryzae ¡ Conidium Conidiophore Spore tip mucilage Eruption How is host immunity suppressed ? Germ tube Tissue colonisation How is plant tissue Autophagic colonized? cell death Melanin-lined appressorium cell wall Primary invasive hyphae Penetration peg

Th ¡ Invading ¡hyphae ¡are ¡surrounded ¡by ¡the ¡host ¡plant ¡plasma ¡ membrane ¡ Plant ¡membrane ¡ Fungal ¡cytoplasm ¡ Merge ¡ ¡ PtoxA-­‑tdTomato ¡ L06b ¡ ¡ Mentlak et al. 2012 Plant Cell 24: 322-35

Effectors suppress plant immunity 1 180 LysM LysM • 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

Summary 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

Anotida Madzvamuse Chandrasekhar Venkataraman Vanessa Styles University of Sussex Yasin Dagdas Anastasia Desyatova Joseph Turner Lauren Ryder Richard Wilson Wasin Sakulkoo University of Nebraska Barbara Valent Xia Yan Martha Giraldo Magdalena Urdiroz Kansas State University Hiromasa Saitoh Darren Soanes Ryohei Terauchi Mick Kershaw Iwate Rice Biotechnology Center Miriam Oses-Ruiz You-Liang Peng China Agricultural University, Beijing Yogesh Gupta JinRong Xu George Littlejohn Purdue University Bart Thomma Tom Mentlak Wageningen University Naoto Shibuya Meiji University Gero Steinberg Halpin ¡ ¡Trust ¡