Karteikarten
Lecture 30 PMB
Karten in diesem Stapel (21)
- 1Crown gall disease process1) Plant wound is infected
2) A. tumefaciens attaches has a Ti plasmid
3) T-DNA contained w/in Ti plasmid
3) T-DNA transferred to cell, integrated into plant genome
4) Tumorigenesis, production of opions - 2Agrobacterium tumefaciensgram negative, aerobic, rod-shaped
can live on roots or in aerated soil - 3Through what secretion system is T-DNA transferred to plant cell genomes?Type IV Secretion System
- 4Crown gall disease process: Infection of the wounded plantwhen plant is wounded, releases phenolic compounds --> stimulates VirA autophosphorylation --> phosphate transferred to VirG --> VirG activates vir genes --> motility reduced, cellulose fibrils + richadhesin made --> A. tumefaciens better attaches to plant
- 5VirAhistidine kinase located on membrane of A. tumefaciens
stimulated by phenolic compounds
autophosphorylates and passes phosphate to VirG - 6VirGtranscriptional response regulator, when phosphorylated it activates tx of vir genes
- 7Ti plasmid structureT-DNA (oncogenes + opine synthesis genes)
transmissibility genes
opine catabolism genes
vir genes (virulence factors) - 8opine moleculesused as a C & N source for A. tumefaciens
T-DNA directs plant host to synthesize these for the bacterium - 9Crown gall disease process: Processing of the T-DNA from the Ti Plasmidvir genes activated by VirG-P --> VirD endonuclease nicks Ti plasmid at T-DNA borders --> VirE binds single strand of T-DNA & transports to plant cell --> VirD remains bound to one end of T-DNA during transfer
- 10Crown gall disease process: T-DNA transferred to host cell & integrated into genomeT-DNA transferred via Type IV secretion: composed of proteins VirB1-11 + VirD4
T-pilis attaches to host
plant DNA polymerase produces complementary strand to ssDNA, ds T-DNA is integrated RANDOMLY into host - 11Crown gall disease process: Tumorigenesis and opine productiononc gene: tumor formation, alter plant growth hormones (auxin and cytokinin)
ops gene: production of opines (octopine and nopaline) - 12Modified Ti plasmid in genetic engineeringtwo vectors required: take vir genes and T-DNA border sequences, remove onc and ops genes and replace with gene of interest --> can express target gene in host plant
- 13Arabidopsis T-DNA insertion linescreated by Ti plasmids
is a large collection of transposon mutants in a particular species --> speeds up genetic study of plant biology - 14Creation of GMOscreated from modified Ti plasmids
used to express foreign/modified genes in crop species - 15Rhizobium-Legume Symbiosis1) recognition of partner and rhicadhesin-mediated attachment to root hair
2) secretion of Nod factors to cause root hair curling
3) Rhizobia penetrate root hairs, multiply within infection thread
4) Bacteria move toward main root
4) Rhizobia develop into bacteroid state within root nodule, perform N2 fixation - 16legume infection threadcellulose tube made by plant host, Rhizobia travel through this to main root
- 17Nod factorsoligosaccharides that bind to specific receptors within plant cytoplasmic membrane --> root hair curling + plant cell division --> formation of mature nodule
have N-acetylglucosamine backbone made by NodABC proteins, is specific to species depending on R groups - 18flavonoidsproduced by plants, bind to NodD receptors of correct symbiont
activated NodD drives tx of other nod genes --> nodABC genes synthesize Nod factors - 19Root nodule metabolismbacteria gets TCA intermediates from plant photosynthesis --> creates PMF and ATP using aerobic respiration
Pyruvate + CoA + Fd(ox) → Ac-CoA + CO2 + Fd(red)
Using Fd(red) as donor, fixed N (glutamine and asparagine) is shared with plant - 20Leghemoglobin (Lb)made by the plant
--> binds O2 to keep the free oxygen tension in the root nodule low + prevent damage to nitrogenase enzyme
cell still uses O2 as electron acceptor so most of it is bound to Lb - 21symbiosomederived from plant cytoplasmic membrane, surrounds colony of bacteria
N2 fixation occurs AFTER this forms
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- Beschreibung
- Plant-Microbe Interactions
- Erstellt von
- Candice Young
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