Age related resisitance in plants
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Age related resisitance in plants

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    Age related resisitance in plants Age related resisitance in plants Presentation Transcript

    • Manjappa PAL 0203 Sr. M. Sc. Dept. of Genetics & Plant Breeding UAS, GKVK, Bangalore, India University of Agricultural Sciences, GKVK, Bangalore-65
    • 3
    • Host factors that affect development of epidemics Level of Genetic Resistance or Susceptibility of host Degree of Genetic uniformity of host plants Type of crop Age of host plants 4
    • Host Defense Mechanisms 1. Basal resistance Recognition of microbe-associated molecular patterns (MAMPs), such as bacterial flagellin 5
    • 2. R gene-mediated resistance: (HR) 6
    • SAR and ISR Response Pathway 7
    • Life span of the plant Susceptibility Growth period Adult period 3. Age related resistance (ARR) 8 (Change of susceptibility of plant parts with age)
    • Effect of Crop age rate of infection Cassava planting of different ages exposed to African Cassava mosaic geminivirus show increased resistance to infection as they age. 9
    • Age Related Resistance Increase or acquisition of resistance to pathogenic infections as a function of plant development. Eg: rice/Pyricularia oryzae & rice/Xanthomonas compestris pv oryzae Syn: ontogenic resistance, developmental resistance, mature seedling resistance, adult seedling resistance. 10
    • Positive correlation between increasing plant age & glyceollin production - Phytophthora megasperma var. sojae (Soybean) Cotton phytoalexin in response to Verticillium albo-atrum Constitutive accumulation of terpenoids in cotton Capsidol- phytophthora capsici Toxic compounds Defense associated compounds - In tobacco PR proteins – PR1, PR2 & PR3 against virus & fungal pathogens - Salicylic acid in Tobacco & Arabidopsis ARR mechanisms will differ with crop/pathogen interaction 11
    • Age-related Resistance in Arabidopsis Is a Developmentally Regulated Defense Response to Pseudomonas syringae • Arabidopsis thaliana ecotype Colombia (Col-0), mutants npr1- 1, etr1-4,pad3-1, eds7-1, sid1 and sid2 & transgenic NahG line • Avirulent & virulent strain of Pseudomonas syringae pv tomato (Pst) strain DC3000 & P. maculicola(Psm) strain 4326 Julianne et al. (2002) The Plant Cell 12
    • Col-0 plant leaves 8 & 16 were inoculated with Pst @ 106 cfu/mL from 26-57 dag at 1 wk internal Old plants become more resistant to Pst i.e. 10 fold reduction in bacterial growth between 30 & 40 dag. There was no significant difference in leaf 8 & 16 bacterial levels- differences in leaf morphology do not affect ARR 50 dag 13
    • Defective for SAR More susceptible Accumulates very less Camalexin, wild type Susceptible to Pst & Psm, Wild type to SAR Defective in ethylene signaling & ISR ARR is not require ethylene signaling & not an ISR response to PGPR SAR not requires to ARR No effect on ARR In Planta Bacterial Growth In Young and Mature Arabidopsis Mutants 14
    • Then which factor is responsible ?... • Transgenic NahG & mutant sid1 and sid2 plants (accumulate little SA) were tested to determine whether SA accumulation is required for ARR response. Both sid1 & sid2 supported vigorous in planta bacterial growth in young & mature plants in a manner similar to NahG, unlike wild-type Col-0. SA accumulation is required for ARR 15
    • Accumulation of SA act as a signaling molecule, stimulating the production and secretion of heat stable anti-microbial compound(s) into the intercellular space Antimicrobial activity was detected only in IWFs from mature plants inoculated with Pst, not in IWF from mature mock- inoculated plants ARR is developmentally regulated and pathogen induced response in Arabidopsis. 16
    • Stress induces an ARR-Like responses in young plants  Mild nutrient limitation can affect the level of in planta growth of Pst.  In young rice, wounding of one leaf induces accumulation of Jasmonate & local activation of PR genes. This is correlated with ISR to subsequent blast disease.  Mild drought- reduced in planta bacterial growth (2-6 fold) compared to control plants of same age  Constantly wet soil sometimes supports algal growth & that plants grown under these conditions exhibit reduced growth of Pst. 17
    • Forms of ARR 1. Resistance & developmental transition 2. Resistance & tissue maturity 3. Increased or acquired resistance & plant development 4. specific & broad spectrum resistance In Turnip and Arabidopsis, the long-distance movement of CaMV is influenced by the developmental stage of the invaded leaves & progressively more restricted to basal portion of lamina during growth 18
    • 19
    • 1. Resistance & developmental transition Postembryonic /vegetative in Arabidopsis Col-O ecotype develop resistance in true leaves against DM fungi but not so in Ws-O ecotype (it lacks RPP31) Juvenile/adult transition during vegetative growth In maize Corngrass1 mutant (Cgm1), the juvenile-vegetative phase is extended & adult resistance to common rust (Puccinia sorghi) is delayed. There fore expression of adult characteristics are necessary for leaf resistance. In Cabbage adult stage is resistant to DM than cotyledony stage 20
    • Cont… Correlation between floral transition & resistance Arabidopsis resistance to CaMV & Pseudomonas syringae. Confirmed by terminal flower 1 (tfm) mutant. (TFL1 Protein floral induction & maintenance of floral identity in apical meristem) PR1 & PR2 are specifically expressed in tobacco floral tissue Resistance may correlated with senescence. (Not so in Arabidopsis/Pst to SAG13) 21
    • Developmentally regulated mechanisms affect the ability of a fungal pathogen to infect and colonize tobacco leaves Karine Hogot et al. (1999), The Plant Journal, 20(2) Vegetative phase Flowering phase Control infection effectiveness (intercellular fluid, not SA) Restriction of fungal hyphae expansion (PR1 & SA accumulation) Material & methods: Nicotiana tabacum cv Xanthi nc., transgenic lines NahG-8 & NahG-9 expressing or not expressing NahG genes (codes for Salicylate dehydrogenase, converts SA to catechol) Phytophthora parasitica isolate 329, infiltrated 50µl of suspension (100 zoospores) 22
    • Tobacco plants begin to express developmental resistance at 75-85 das An average of 60% of the inoculated zones showed disease symptoms, but spreading was reduced by 80% not only control of fungal hyphae expansion but also decrease in infection efficiency during flowering phase 23
    • SA-dependent & SA-independent mechanisms Expression of mechanisms which lead to control of fungal devt. after floral transition require SA accumulation. Increase in inoculated zones without any symptoms of diseases in NahG-8 shows, induction of events that affect the ability of fungus to infect leaf tissue do not require SA accumulation 24
    • Acquired resistance during development & apoplastic PR1 protein accumulation Establishment of SAR leads to systemic transcriptional activation of a subset of PRs genes Immunoblotting expt’s were undertaken to study accumulation of PR1 protein in apoplasm during plant devt. Xanthi nc plants were treated with cryptgein to induce SAR. (induced PR proteins) PR1 Protein expression was correlated with the ability of tobacco to inhibit the fungal devt. in planta rather than infection effectiveness during flowering IFs (Hammond-Kosak)- Protein extract 15% SDS-PAGE electrophoresis Incubate Nitrocellulose membrane with IgG antibody Goat peroxidase cojugated IgG Detection system (Amersham) 25
    • Which controls Infection effectiveness during flowering ? • Intercellular fluid (cytotoxic activity) Survived cells germinated cells:::: The influence of Ifs on in vitro germination of zoospores Zoospores (5x105) were incubated for 2 h in the presence of different IFs Cytotoxic activity on fungal cells was not detected in IFs from cryptgein treated Xanthi plants. The expression of an in vitro cytotoxic activity on fungal cells in IFs is from plant committed to flowering 26
    • 2. Resistance & Tissue maturity • Several plant species develop resistance that is restricted to a given tissue or organ, as a function of maturity. • Soybean: Resistance to Phytoophthora sojae in hypocotyl varies with tissue maturity. • Apple tree: Leaf maturity is positively correlated with resistance to Venturia inequalis • Maize: During vegetative growth, leaves with juvenile traits are susceptible & leaves with adult traits are resistant (>8th node) to Puccinia sorghi • Rice: Leaf maturity has no effect on the degree of resistance to Xanthomonas compestris pv. oryzae, where as leaf rank does have an effect. 27
    • Effect of Age & Leaf Maturity On the Quantitative Resistance of Rice Cultivars to Xanthomonas campestris Pv,oryzae • Materials: Cisadane, BR51-282-8(BR51), IR28, IR40 are moderately resistant. • TN1 & IR9101-46 (9101)- susceptible checks • Xanthomonas campestris ov. oryzae race2 strain PXO86 & race6 strain PXO99 (1 X 109 cfu/ml) } Largest decrease in lesion length (cm) Koch et al. (1991), American Phytopath. Soc. 28
    • Cont… Decrease in lesion length was less evident after maximum tillering, but flag leaves were more resistant than leaves at booting stage No significant age X cultivar interaction was found Plant age does not greatly affect our ability to distinguish among intermediately resistant cultivars Difference in lesion length between immature and mature leaves was similar in all cultivars Screening for quantitative resistance to X.c. oryzae can be done at all stages of growth 29
    • 3.Increased or acquired resistance & plant development Rice: Xoo & X. compestris pv. Oryzae Pyricularia oryzae Tobacco: TMV, Peranospora tabacina Soybean: Phytophthora sojae Arabidopsis: Hyaloperanospora parasitica Wheat: P. recondita f.sp. tritici 30
    • 4a. Developmental effect on Specific resistance • ARR may be effective against several pathogens, a particular pathovar, strain or race of pathogen Crop Gene(s) Pathogen Rice Xa6 X. Campestris pv. oryzae Xa21 X. oyzae pv. oryzae Wheat Lr gene fam. (few) P. recondita f.sp. tritici Sr gene fam. (few) P. graminis f.pv. Tritici Tomato Hcr9-9A, Hcr9-9B, Hcr9-9th Cladosporium falvum Maize Cg1 Puccinia sorghi 31
    • Developmental control of Xa21-mediated disease resistance in rice  Reproducible means of infecting plants at full leaf expansion  Xa21-resistance progressively increases from the susceptible juvenile leaf 2 stage. Resistance (%)= 1 Xa21 line mean lesion length susceptible line lesion length - X 100 32
    • Cont..  Xa21 expression is independent of plant developmental stage, infection with Xoo, or wounding  Expression of the Xa21 gene transcript is not correlated with expression of Xa21 disease resistance Developmental regulation of Xa21-resistance is either controlled post-transcriptionally or by other factors XA21 has an intracellular serine–threonine kinase domain, it is a likely possibility that XA21 activity is controlled by phosphorylation status Rice Xa21 binding protein 3 is a ubiquitin ligase (HB3) required for full Xa21-mediated disease resistance 33
    • 4b. Developmental effect on Broad spectrum resistance Flowering growth in tobacco: express resistance to Peranospora tabacina, Phytophthora parasitica & TMV Mature Arabidopsis: Pseudomonas syringae pv. tomato and pv. maculicola as well as Hyaloperanospora parasitica After onset of berry ripening in grape: express resistance to 3 ascomycetes Control of viral migration (CaMV) in Turnip & Arabidopsis. 34
    • Genetic Analysis of Developmentally Regulated Resistance to DM (Hyaloperonospora parasitica) in Arabidopsis thaliana  ARR to H. parasitica Emco5 is activated in true leaves of Arabidopsis Col-O but not Ws-O:  Ws-O is highly susceptible to Emco5 throughout the devt., in contrast to Col-O (shows delayed HR) McDowell et al. (2005), American Phytopath. Soc. S-Sporangiospore, O-oospore,TN- Trailing necrosis, H-hyphae 35
    • Adult resistance in Col-O is race-specific & is suppressed by defense signal transduction mutants Adult Col-O plants are susceptible to H. parasitica isolate Noco2 & Ahco2 Trailing necrosis/HR & H2O2 production in true leaves indicates, it is results from active defense response of host Each of isogenic Col lines is deficient in SA- mediated signaling their by impairing basal resistance, SAR & certain R genes Adult resistance in Col-O requires variety of regulatory components previously associated with inducible defense 36
    • Genetic analysis of Adult resistance  Phenotypes in F1 indicates susceptibility is incompletely dominant over resistance.  F2 segregation ratio: 24% Col-like adult resistance (1):76% full/intermediate susceptible (3)- indicates single recessive gene controls Segregation of adult resistance to Hyaloperanospora parasitica Emco5 Cross F1 F2 Sus Int Res Res rpm1-3 (Col- 5) x Ws-O 0 8 1 30 89 1.09 (P>0.3) Col-O X Ws-O 0 6 3 Ws-O X Col-O 0 2 4 37
    • Recessivity of resistance in Col-O x Ws-O hybrid could be a gene-dosage effect ! XWs-O (2x) Col (CS3151, CS3432-4x) F1 (3x) Col/Col/Ws-O Susceptible But supported less sporulation than Ws-O parent & diploid F1 Ws-O susceptibility phenotype is incompletely dominant to adult resistance in Col-O. Genetic mapping in a Col x Ws F2 population revealed a major locus on the bottom arm of the chromosome 5, named as RPP31 38
    • Molecular Mechanisms of Developmental Resistance 39
    • Cont… Crop Developmental control Response Pathogen Tobacco Flowering PR1a,PR2 Chitinase, ß- (1-3) glucanase, peroxidase TMV Peranospora tabacina Grape Berry ripening Chitinase, PR5, LTP U. necator Hordeum vulgare Embryo developing Before grain desiccation 9-LOX (Lipoxigenase) pathway PR Pathogens Developmental resistance also involves up-regulation of gene involved in modification /strengthening of cell wall along with defense genes 40
    • Defense mechanisms in Arabidopsis • SA has antimicrobial activity & partially rescues the iap1-1 ARR defect. 41 Suggesting iap1-1 lies up-stream of SA accumulation in ARR pathway. Prediction: iap1-1 accumulates little intercellular SA. Leaves of 5 wk old plants inoculated with Pst at 5 & 24 h post infiltration Level of SA in Pst or mock inoculated mature plants measured by Gas chromatography-mass spectrometry
    • Cont…  Addition of SA in the intercellular space of eds1-1 plants did not result in the rescue of the eds1-1 ARR defect. EDS1-1 at down- stream of SA  Combining microarray analysis with reverse genetics using T-DNA insertion lines, 4 additional genes were identified, UGT85A1, CDA1, ANAC055 and ANAC092 42 iap1-1 Salicylic acid eds1-1 UGT85A1, CDA1, ANAC055 and ANAC092 Defense to infection Carviel, J. L., et al.,2009, Mol. Plant Path., 10(5): 621-634
    • PR proteins (PR3, PR5, nsLTP) are express constitutively at low level in cells and accumulate in response to fungal attack or inducers of acquired resistance with the exception to reproductive organs (developmentally regulated expression). 43
    • A. Pattern of protein accumulation in grape berry during ripening. B. Comparison of total protein profile of susceptible Vs resistant variety to Botrytis cinerea Developmental accumulation of antifungal proteins like – thoumatin like protein (GO), chitinase (CBC & AC forms) & ns LTP and hexoses in grape berry provide resistance against Guignardia bidwellii (fruit rot) & Botrytis cinerea GO nsLTP AC CBC 44
    • 45 Sugar molecules may act as a signal molecule to regulate the expression of antifungal proteins genes during fruit ripening. Sugar repress genes which codes for C-assimilatory enzymes Up-regulates genes for protease inhibitors, chalcone synthase, PR3, PR1b & PR-Q Sugar and antifungal proteins interact to mediate host plant defense against phytopathogens either by Disruption of fungal gene regulation by sugar repression Solute mediated preservation of native protein structure (CBC, GO)
    • Relationship between defense & development in plants Expression of resistance to disease during host devt. Involvement of plant hormones in devt. & P-P interaction Eg: SA, JA, Ethylene, ABA Molecular conservation of transduction pathways governing various process  Eg: Arabidopsis- In csa1 mutant TIR-NBS-LRR protein involved in photomorphogenic devt. is complemented by RPS4 (homologue of TIR-NBS-LRR confers resistance to Pst)  Tobacco transcription factors of the TGA family: TGA2.1- SA inducible gene expression & TGA 2.2- regulatory role in correct stamen devt. 46
    • Conclusion 47