Lecture 6-Crown gall tumour Flashcards
Agrobacterium tumefasciens
common soil bacterium, sends TDNA into wounds of plant that is tumor inducing. borne from aerosols, rainsplash
acetosyringone
compound released by plants
VirA/G sensor proteins
detects plant compounds, triggers signal transduction in bacterium, cause trascription of Vir genes in Ti plasmid
Plasmid
small independently replicating pieces of DNA
Vir genes
produce transcripts that produce vir proteins
VirB
build pilus(entry point) to breach plant cell. help move other protein complexes through pilus into plantcell
Vir D1/D2 protein complex
cuts out some DNA from ti-plasmid (called T-DNA) (transfer)
Complex protein
2 or more linked proteins
Plasmid DNA
single strand, bound 5’ to VirD2, also a complex-nucleic acid (TDNA) and protein (VirD2) looks like telephone cord
VirE2
protein that coats plasmid DNA complex
acts as: 1. protection from nucleases
2. provision of signal, has NLS recognized by protein (importin alpha) at nucleopore
TDNA once in nucleus
separates from other proteins in complex, bacterial protein splices DNA into plant chromosomes
illegitimate recombination
splicing of TNDA into plant chromosomes
Opines
produced by enslaved plant cell, useless to plants, produced/exported to feed bacterium
Genetic colonization
plant parasitized by genetic parasites
Bioengineering of insulin
- human insulin gene put in E. coli (bacterium), raised in fermentors to produce massive amounts of insulin
academic genes
used to study physiological responses
eg photosynth, terpene synth
industrial genes
used to confer insect resistance and herbicide resistance
How to create a transformed plant
sterile leaf
1punch hole in leaf
2.dip disc in solution of A. tumefasciens that has gene of interest in plasmid
3. put disc in tissue culture to regenerate whole plant
4. put plants into greenhouse to breed and test for new character then bulked to produce commercial seed
single gene transfer
most powerful crop improvement tool ever invented
Amount of genetically transformed crops in world
125 million acres
Domain
porrtion of plant that is highly well-connected by symplast
Plasmodesmata size exclusion limits
do not allow molecules that exceed 1000kDa
3 states of Plasmodesmata
closed,open, dilated
Dilated plasmodesmata size limit
27kDa
eg Green fluorescent Protein
Action potential in venus fly trap
in hair cell,stored Ca is released into cytoplasm, increased [ ] causes membrane depolarization. change in charge spreads from cell to cell until trap closes. transmitted via plasmodesmata of sensory hairs
Aldrovandra vesiculosa. waterwheel plant
snap trap like venus fly trap, shuts in 0.02s. one of fastest responses in entire world
