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64 Cards in this Set
- Front
- Back
Blocks plasmodesmata during infection |
Callose |
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Projection from fungus hyphae that penetrates cytoplasm |
Haustorium |
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3 enzymes fungi use to break down plant cell walls |
Cutinase, pectinase, cellulase |
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4 physical defences against plant pathogens |
Cuticle, lignin, callose and silicon |
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Parasite that depends on living tissue |
Biotrophs |
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Parasite that depends on dead tissue |
Necrotrophs |
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Depends on living tissue, then dead tissue |
Hemibiotrophs |
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Chemical makes fungus/bacteria membrane leaky and is toxic to insects and is an antifeedant |
Saponins |
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After wounding by herbivores, are activated into toxic mustard oils |
Glucosinolates |
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Antipathogen, Inserts into plasma membrane, four make a pore. Broad spectrum. |
Defensin |
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Maize targeted toxin, inhibits histone deacetylases and nucleosome unwinding. |
Maize HC toxin |
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inactivates HC toxin |
HC toxin reductase |
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Three types of inducible defense |
PAMP triggered immunity. Effector triggered immunity. DAMP triggered immunity. |
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Generic immune response, initiated externally by pattern recognition receptors. |
PAMP (pathogen associated molecular patterns) triggered immunity. |
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Pattern recognition receptors respond to... |
Chitin, flagellin, lipopolysaccharides, ds RNA, cell wall and cuticle fragments. |
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Internal initiation of immunity, specific |
Effector triggered immunity |
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Triggers for effector triggered immunity |
Proteases, glycolipids |
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Triggers for DAMPs |
Cellulose, salicylic acid, bits of cell wall |
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Rapid death of cells in region of infection |
Hypersensitive response |
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Phase 1 of hypersensitive response |
Activation of R genes triggers action potential of k efflux and ca/h influx |
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Phase 2 of hypersensitive response |
Oxidative burst (ROS) break down membrane, trigger deposition of lignin and callose. Systemic: inhibitors of enzymes and chitinases, phytoalexins. |
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Phase 3 of hypersensitive response |
Intracellular signalling to nucleus, transcribe defense proteins (structural or anti fungal). Cell death, endonucleases, proteases. |
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Inactivator of Salicylic acid |
Salicylate hydroxylase |
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Stable analogue of Salicylic acid |
BTH |
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Salicylic acid receptor |
NPR1 |
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PAMP triggered immunity responses |
Oxidative burst/ROS wave, callose deposition, make salicylic acid and ethylene |
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Incompatible interaction |
Elicitor recognised by r protein |
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R proteins recognise... |
Avirulence (avr) proteins |
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Elicitor of systemic acquired resistance |
methyl salicylic acid |
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Programmed cell death vs... |
Systemic acquired resistance |
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Function of NPR1 |
DNA binding, enhances transcription of pathogen response genes (chitinases, toxic volatiles, antimicrobials). Directs cell down systemic acquired resistance pathway. |
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NPR4 binds salicylic acid stronger or weaker than NPR3 |
Weaker |
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Role of NPR3 |
Mediates degradation of NPR1 when bound to salicylic acid, encourages cell death |
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Role of NPR4 |
When bound to salicylic acid, it doesn't break down NPR1, favours genes associated with systemic resistance |
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Make systemic acquired resistance more rapid? |
Overexpress NPR1 |
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How to transfer induced pathogen response between species? |
Clone pattern recognition receptor between species. Eg from model to tobacco |
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Defensin overexpression example |
Protect potato against fungus but yield penalty |
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How to combat nematode with biotechnology |
Express ds RNA for peptide that induces giant feeding cells |
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Plant response to salinity |
Reduced transpiration, accumulation of inorganics in vacuole and osmoprotectants in cytoplasm |
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Three ways to identify genes associated with abiotic stress resistance |
Quantitative trait loci, genome wide association studies, mutation screen and yeast complementation studies |
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Three general targets for drought, salt or temperature tolerance |
Osmoprotectants, ion transporters/channels, transcriptional activators of stress tolerance genes |
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Two examples of drought tolerance |
Rice: deeper rooting 1 (DRO1) increases gravitropism. Maize: Overexpression of trehalose-6-phosphate synthase improves yield in all moisture conditions. Is osmoprotectant. |
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Four salinity tolerance strategies |
Overexpress vacuolar Na/H antiporter AtNHX1 in oil seed rape and tomatoes. 200mM NaCl. Overexpress AVP1 H pump. More protons in vacuole. Overexpress SOS1 Na/H antiporter (less Na in cell) HKT1 transports Na out of xylem to parenchyma cell. Tissue specific overexpression in root stele. |
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Four cold tolerance strategies |
Abscisic acid treatment Upregulate COR genes Proline accumulation (osmoprotectant) Eskimo1 mutant |
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COLD1 SNP effect |
Makes japonica rice more cold tolerant than indica rice |
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Effect of CBF3 overexpression on yield |
Lower yield if constitutive, if inducible higher drought, salt and freezing tolerance |
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Aluminium resistance strategies |
Excretion of organic acids (malate, citrate) Raise pH of rhizosphere |
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Transporter that confers high Aluminium resistance |
Malate transporter |
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Polyploidy |
Plants with more than two paired homologous sets of chromosomes. |
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Homeologues |
Orthologous genes in the same species due to recent polyploidy. |
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Orthologues |
Genes originating from a single ancestral gene in last common ancestor of compared genomes. |
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Polyploid species example |
Brassica napus, oilseed rape |
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Genome of Brassica napus |
AACC |
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Ancestors of Brassica napus |
Brassica rapa and Brassica oleracea |
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Brassica rapa genome |
AA |
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Brassica oleracea genome |
CC |
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Three factors that make sequencing plant genomes more challenging |
Polyploidy, highly repetitive regions, many genes/large genome |
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Challenge facing detection of allelic sequence variation |
SNPs between homeologues can be mistaken for allelic variants. |
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How to detect and score allelic sequence variation |
High sequence redundancy, sequence-based SNP calling against reference sequence |
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Two requirements for development of genomics platforms for plants without high quality genome sequences |
Genome sequencing and genetic linkage map |
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How to make genome sequence for making genomics platform |
Assemble short read contigs with longer reads and assemble genome sequence scaffolds |
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Statistical analysis of coinheritance of alleles is... |
Genetic linkage map of ordered markers. Hypothetically ordered genes |
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Density and resolution of linkage map dependent on... |
Scaffold size |
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If large scaffolds not available for SNP calling then use... |
Scaffolds from related species, contiguous genome better |