Plant immunity

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Information about Plant immunity

Published on April 6, 2014

Author: chinnupavi4485


PowerPoint Presentation: Seminar on “ Plant immunity: towards an integrated view of plant pathogen interaction and its implication in plant breeding ” Pavan.R PALB1061 1 PowerPoint Presentation: 2 PowerPoint Presentation: 3 PowerPoint Presentation: 4 PowerPoint Presentation: 5 PowerPoint Presentation: “For each resistance gene in the host there is a corresponding gene for avirulence in the pathogen cnferring resistane and viceversa” Host plant genotype Pathogen genotype R1 r2 r1 R2 Avr1, avr2 I I C C avr1, Avr2 I - incompatible - no disease C - compatible - disease Gene for gene hypothesis H.H. Flor 6 PowerPoint Presentation:  It is a state of defense against infectious pathogens Pathogens are like Bacteria, Fungi, Virus, Nematode, Oomycetes etc. Mode of entry of pathogen depend on type of pathogen Bacteria – stomata, hydathodes and wounds Nematode – Stylet Fungi – Haustoria What is plant immunity? 7 PowerPoint Presentation: Principles of plant immunity 8 PowerPoint Presentation: Forms of plant resistance Antipathy- Lack of interest of pests or pathogens in a plant. Ex- Resistance of Arabidopsis to insects - Glucosinolate contents Hindrance- Lack of pathogen’s ability to parasitize the plant because of certain plants features Ex-higher levels of calcium - macerating pathogens through strengthening the cell walls ( Datnoff et al. 2007) Defence- Based on the plant innate immune system 9 PowerPoint Presentation: PAMPs Triggered Immunity (PTI) Effector triggered susceptibility (ETS) Effector Triggered immunity (ETI) Natural selection Phases of Plant immunity 10 PAMP Triggered Immunity (PTI): PAMP Triggered Immunity (PTI) PAMP (Pathogen Associated Molecular Pattern) The molecules of pathogens, conserved across larger group of pathogens Highly indispensable to the pathogens, required for their survivality These molecules do not exist in host Ex. Flagellin, EF-Tu, lipid, chitin, protein molecules of pathogens 11 PRR (Pattern recognition receptor): Plasma membrane-localized receptors that recognize the presence of PAMP’s in the extracellular environment. Located in plasma membrane Ex. FLS2, ERF, CEBiP, etc PRR (Pattern recognition receptor) 12 ETS (Effector Triggered Susceptibility):  ETS (Effector Triggered Susceptibility) Effector are any regulatory molecules secreted by pathogens Modifies host protein to establish their growth Effector perform three main functions Structural role : Ex. Fungi, secret extra haustorial molecule Nutrient leakage : Ex . P. syringae HopM effector protein Pathogenicity : Ex. HopA 1 dephosphorylates MAP kinase results in inhibition of PTI 13 PowerPoint Presentation: The plant defence response elicited by effector recognition. The effector molecules are recognized by R protein Four major classes of R genes NB-LRR (nucleotide binding leucine rich repeat) genes Ser/ Thr kinases Receptor-like kinases (RLKs) Receptor-like proteins (RLPs) Effector triggered immunity (ETI) 14 PowerPoint Presentation: Different phases of the zig-zag model Jonathan & Jeffery, 2006 15 PowerPoint Presentation: Model for resistance in plants 16 PowerPoint Presentation: Defence responses post-pathogen recognition 17 PowerPoint Presentation: Stomatal closure Ion fluxes Oxidative burst Phyto -Hormone action Induced systemic resistance Systemic Acquired Resistance 18 Defence Mechanism of plant toward off pathogens 1. Stomatal closure: 1. Stomatal closure Stomata are natural opening through pathogen can easly enter into apoplast Stomatal closure is part of a plant innate immune response to restrict bacterial invasion. 19 PowerPoint Presentation: Bacteria and PAMPs Trigger Stomatal Closure in Arabidopsis 20 Maeli etal , 2006 (1) Stomata actively closes as an initial response to both plant and human pathogenic bacteria, (2) Pst DC3000 has evolved a mechanism to reopen stomata 3 hr after incubation (3) Inoculum concentration 1x 10 7 cfu /ml 1hr-closure & 3hr-Reopen PowerPoint Presentation: Involvement of the FLS2 Receptor and Salicylic Acid in PAMP Induced Stomatal Closure 21 flg22: biologically active peptide derived from flagellin MES: Buffer LPS: Lipopolysaccharides PowerPoint Presentation: 22 Col-0: Wild type fls2: Flagellin receptor mutant PowerPoint Presentation: 23 Salicylic Acid in PAMP Induced Stomatal Closure eds 16-2: SA-biosynthetic mutan plant nahG : SA-deficient transgenic plants PowerPoint Presentation: Model Depicting Bacterium- and PAMP-Induced Stomatal Closure in the Arabidopsis Guard Cell 24 Subunit of E3 ubiquitin ligase involved JA signalling PowerPoint Presentation: 25 2. Ion fluxes Membrane permeability changes rapidly leading to a loss of cellular electrolytes such as K + and an uptake of H + . At the same time, there is often an influx of Ca 2+ , a key intracellular signal in plants that is involved in the activation of enzymes and gene expression. The experimental blocking of Ca 2+ transport across membranes in inoculated bean cells also inhibits gene activation and subsequent defence responses . PowerPoint Presentation: 26 3. Oxidative burst It is a rapid, transient, production of huge amounts of reactive oxygen species (ROS) Produced from membrane localized NADPH oxidase (Nuhse et al, 2007) JA/SA pathway activated, finally PCD PowerPoint Presentation: 27 Abbreviations used : AC, adenylate cyclase ; CWP, cell-wall-bound peroxidase ; E, elicitor; Er: receptor; G, GTP-binding protein(s); PLase A and PLase C, phopholipases A and C; R, reductant. Schematic representation of major hypotheses describing the possible origin of ROS building the oxidative burst PowerPoint Presentation: 4. Phyto -hormones 28 PowerPoint Presentation: Rapid death of cells in the local region surrounding an infection. Restrict the growth and spread of pathogens to other parts of the plant. Favor growth of pathogens with a necrotrophic lifestyle 5. Hypersensitive response 29 PowerPoint Presentation: 30 Biotrophic: pathogens propagate in living plant tissue and generally do not cause necrosis as a result of infection. Necrotrophic: pathogens actively induce necrosis in infected tissues, often through the production of toxins. Hemibiotroph: An organism that is parasitic in living tissue for some time and then continues to live in dead tissue PowerPoint Presentation: It is secondary resistance response Because, once plant defense responses are activated at the site of infection , a systemic defense response is triggered in distal plant parts to protect these undamaged tissues against subsequent invasion by the pathogen. Long-lasting and broad-spectrum induced disease resistance Act non-specifically through out the plant and reduce disease severity 6. Systemic Acquired Resistance(SAR) 31 PowerPoint Presentation: 32 SAR signal is a generated with in 4hr of inoculation SA could be detected in phloem of leaf 8hr after inoculation Increased level of SA in phloem of leaf above the incubated leaf Expression of SAR occurs with in 24hr after inoculation PowerPoint Presentation: 33 PowerPoint Presentation: 34 PR proteins (PRP) Proteins produced in plants when it is attacked by pathogen, they are antimicrobial/viral/ insecticidal Its extremely acidic/ basic in nature, therefore it is highly soluble an highly reactive. Crosslink the molecules of cell wall and acts as barricade by accumulation of lignin which helps the cell wall to protrude as papillae. Gives alarming signals to neighbouring cells It present in both resistant and susceptible plant, but concentration is differs. When there is infection its concentration increases and viceversa. PowerPoint Presentation: 35 PR proteins Plants in which PRP detected Function PR1 Rice, barley, maize, tomato, tobacco Plant cell wall thickening, resistance to the spread of the pathogen on the apoplast PR 2 Rice, barley, maize, tomato, tobacco, potato, pepper, bean, Brassica , sugar beet β -1-3-glucanase PR3 Rice, maize, tomato, pepper, sugar beet, rape seed Chitinase PR 4 Tomato, tobacco, rubber tree Chitinase PR5 Rice, wheat, barley, oats, tomato, tobacco, potato Alternation of fungal memnrane PR6 barley, tomato, tobacco Proteinase inhibitor PR7 Tomato Endoproteinase PowerPoint Presentation: 36 PR proteins Plants in which PRP detected Function PR8 Cucumber Chitinase PR9 Tomato, rice, tobacco, wheat Peroxidase PR10 Potato, asperagus , pea, bean, rice Ribonucleases PR11 Tobacco Chitinase PR12 Arabidopsis, pea, Defensin PR13 Barley Thionin PR14 Barley Lipid transfer proteins PR15 Barley Germin like oxalate oxidase PR16 Barley and wheat Germin like proteins without oxalate oxidase PR17 Wheat, barley, tobacco Peptidase PowerPoint Presentation: Breeding and biotechnological strategies used to induce resistance (Immunity ) in plants 37 PowerPoint Presentation: 38 1. Manipulating PAMP/MAMP receptors to induce immunity PTI activation is based upon the recognition of microbial surface structures (PAMPs/MAMPs), such as bacterial flagellin, bacterial elongation factor EF-Tu or fungal chitin. For example, Arabidopsis FLS2 and EFR are plasma membrane receptor kinases that sense flagellin or EF-Tu through binding to their leucine-rich repeat (LRR) ectodomains PowerPoint Presentation: 39 2010 PowerPoint Presentation: 2. Pyramiding and Introgressing R gene 40 2003, PNAS Late blight, caused by the oomycete pathogen Phytophthora infestans , is the most devastating potato disease in the world The wild diploid potato species Solanum bulbocastanumis highly resistant to all known races of P. infestans PowerPoint Presentation: 41 Cloning of the major resistance gene RB in S. bulbocastanum by using a map-based approach in combination with a long-range (LR)-PCR strategy. A cluster of four resistance genes of the CC-NBSLRR (coiled coil–nucleotide binding site– Leu -rich repeat) class was found within the genetically mapped RB region. Transgenic plants containing a LR-PCR product of one of these four genes displayed broad spectrum late blight resistance. PowerPoint Presentation: Late blight, caused by the oomycete pathogen Phytophthora infestans , 42 PowerPoint Presentation: Genetic and physical maps of the genomic region 43 BAC clones from the RB haplotype (filled boxes) and BAC clones from the rb haplotype (open boxes). Both 177O13 and CB3A14 contain one truncated and four complete RGAs. The direction of transcription of each gene(an arrow). The 3.6-kb deletion region between RGA2 and RGA-tris marked. PowerPoint Presentation: 44 Late blight screening of transgenic plants by using isolate US930287 Plants were scored as resistant (R) if the resistance score was >7.0 (< 25% infection) and plants were scored as susceptible was <6.9 (>25% infection). † Of the 14 resistant plants, nine plants had a score of 7 and five plants had a score of 8. PowerPoint Presentation: Complementation analysis of putative RB genes 45 (A–C) Transgenic Katahdin plants- RGA1-PCR, RGA2-PCR , and RGA4-PCR , respectively. (D) Control Katahdin plant. (E) Katahdin plant that was not inoculated. (F–I) Transgenic Katahdin plants containing constructs RGA1-BAC, RGA2-BAC,RGA3-BAC, andRGA4-BAC, respectively. PowerPoint Presentation: Structure of the RB gene and the deduced RB protein. 46 PowerPoint Presentation: Disadvantage of R genes …….? Ectopic expression of R genes can sometimes activate defence pathways in the absence of pathogen Reduced crop yields Reduced Fitness 47 PowerPoint Presentation:  3. Antifungal fusion proteins to induce immunity 48 Fusarium head blight (FHB) or scab of wheat is a devastating disease in warm and humid regions at wheat-flowering periods worldwide. Expression of pathogen-specific antibodies in plants has been proposed as a strategy for crop protection. PowerPoint Presentation: 49 An antibody fusion protein comprising a Fusarium-specific recombinant antibody derived from chicken and an antifungal peptide from Aspergillus giganteus was expressed in wheat as a method for protecting plants against FHB pathogens. Plants expressing the antibody fusion displayed a very significantly enhanced resistance in T2 and T3 generations upon single-floret inoculation with the macroconidia of Fusarium asiaticum, the predominant species causing FHB in China, indicating a type II resistance. PowerPoint Presentation: Structure of AG-D2 fusion construct 50 An antifungal peptide sequence from Aspergillus giganteus (AG ) and a single-chain Fv (scFv) antibody coding region from chicken. Connected by a sequence encoding a 10-amino-acid glycine-serine linker. The AG-scFv fusion construct was inserted into the plant expression vector pAHC25 using EcoRI and SacI sites. Ubi-Pro, maize ubiquitin promoter; UT: 5′ untranslated region of the petunia chalcone synthase gene; LP, leader peptide sequence; c-myc, c-myc epitope tag; His6, histidine 6 tag; Nos-T-Nos terminator. PowerPoint Presentation: 51 Integration and expression of AG-scFv fusion gene in transgenic wheat. A, T3 transgenic wheat lines 2, and To detect the presence of the AG-scFv fusion gene with primers AGP1 and scFvP2 . B, RNA extracted from leaves of the plants in A was used in a RT- PCR assay to analyze expression of the AG-scFvfusion gene with the same set of primers in A. C, Proteins extracted from leaves in A were fractionated by electrophoresis on a 12% SDS-PAGE and then subjected to immunoblot analysis with an antibody against the Histidine 6 tag PowerPoint Presentation: 52 Southern blot analysis of transgenic wheat. PowerPoint Presentation: Fusarium head blight resistance in T 2 and T 3 transgenic wheat 53 PowerPoint Presentation: 54 Comparison of yield parameters between nontransgenic plants and transgenic plants expressing the antibody fusion. A: Single floret inoculation and B: Spray inoculation PowerPoint Presentation: 55 FHB-susceptible cv. Bobwhite, FHB-resistant cv. Sumai3 at 21 days postinoculation with the conidia of Fusarium asiaticum . A, Spikes of a single floret (indicated by an arrow) inoculated with the conidia of F. asiaticum . B, Spikes by spray inoculation with the conidia of F. asiaticum . C, Grains from a spike of a single-floret inoculation in A. Phenotype of representative spikes and grains from T3 transgenic wheat line 2, PowerPoint Presentation: Phytoalexins are antimicrobial and often antioxidative substances synthesized de novo by plants that accumulate rapidly at areas of pathogen infection They are broad spectrum inhibitors and are chemically diverse with plant species. Phytoalexins tend to fall into several classes including terpenoids , glyco steroids and alkaloids 4. Use of phytoalexins to induce immunity 56 PowerPoint Presentation: 57 1997 Stilbene synthase occurs in several plant species and synthesizes the stilbene phytoalexin transresveratrol Transfer of two genes from grapevine (Vitis Šinifera ) coding for stilbene synthase genes ( vst1 and vst2 ) to tomato by means of Agrobacterium tumefaciens PowerPoint Presentation: 58 The accumulation of the phytoalexin trans-resveratrol , the product of stilbene synthase, for resistance tomato to Phytophthora infestans (Late blight of tomato). Accumulation of resveratrol occurred after inoculation with Botrytis cinerea (Gray mould in tomato) and Alternaria solani (Early blight in tomato) PowerPoint Presentation: Southern blot analysis of transgenic tomato plants of the T 3 progeny 59 Southern blot analysis of transgenic tomato plants of the T3 progeny from regenerant To25 (lane 1±4), To42 (lane 5±8), and transgenic oilseed rape as a positive control (lane c). Genomic DNA was isolated from leaves and digested with EcoRI that generates two fragments of 3.4 kb and 4.9 kb representing the two transferred stilbene synthase genes. PowerPoint Presentation: 60 Northern blot analysis showing the transient accumulation of stilbene synthase mRNA in leaves Northern blot analysis showing the transient accumulation of stilbene synthase mRNA in leaves of a transgenic tomato plant of the T3 progeny from To25 after inoculation with P.infestans. No specific mRNA was detectable immediately after inoculation.*Leaves were treated with tap water only. PowerPoint Presentation: Resveratrol ( stilbenoid , a type of natural phenol , and a phytoalexin ) accumulation in leaves of a transgenic tomato plant from the T2 progeny of regenerant To25 after inoculation with P. infestans and B. cinerea. 61 PowerPoint Presentation: Resveratrol contents of leaves of transgenic tomato plants from T3 progeny of To25 4 days after inoculation with B. cinerea, A. solani, and P. infestans 62 PowerPoint Presentation: Disease symptoms on leaves of a transgenic tomato plant from the T3 progeny of To25 (right) and non-transformed tomato plant (left) 4 days (upper) and 6 days (lower) after inoculation with P. infestans. 63 PowerPoint Presentation:  Biological testing of transgenic tomato plants from progenies T 2 , T 3 , and T 4 of regenerant To25 and To42 for an increased resistance to A. solani, B. cinerea , and P. infestans 4 days after inoculation 64 PowerPoint Presentation: Development of P. infestans on transgenic tomato plant To25 (T 3 progeny) and non-transformed plant 6 days after inoculation 65 PowerPoint Presentation: Incidence of P. infestans on transgenic tomato plants and non-transformed plants in dependence on the leaf insertion 66 PowerPoint Presentation: Probenazole (PBZ) is the active ingredient of Oryzemate Protection of rice plants from Magnaporthe grisea (blast fungus) PBZ pre-treatment increased accumulation of SA and PR proteins in the eighth leaves of adult plants Takayoshi Iwai ., et al 2008 67 5. Use of chemicals to induce immunity PowerPoint Presentation: Phenotypes of blast fungus-inoculated leaves of young and adult rice plants. 68 PowerPoint Presentation: Free SA and SAG levels in rice leaves after fungus inoculation and PBZ treatment. 69 PowerPoint Presentation: Accumulation of rice PR proteins in M. grisea-infected leaves. 70 PowerPoint Presentation: Induced expression of the OsPR1a gene in M. grisea -infected leaves. 71 PowerPoint Presentation: Induced resistance to blast fungus by SA treatment. 72 PowerPoint Presentation: 6. RNAi -mediated silencing of pathogen’s genes Parasitism genes expressed in esophageal gland cells mediate infection and parasitism of plants by root-knot nematodes (RKN). Parasitism gene 16D10 encodes a conserved RKN secretory peptide Used in vitro and in vivo RNA interference to induce immunity 73 PowerPoint Presentation: In Vitro RNAi of 16D10. RNAi silencing of 16D10 in preparasitic M. incognita J2. Fluorescence microscopy showing ingestion of FITC in the treated J2. 74 PowerPoint Presentation: In Vivo RNAi of 16D10. Overexpression of 16D10 dsRNA in Arabidopsis. 75 PowerPoint Presentation: Conclusion 76 PowerPoint Presentation: Thank you 77

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