Making GM Plants Flashcards
What are GMO / transgenic plants?
Plants made by recombinant DNA technology
What are examples of conventional breeding?
- Crossing: sexually compatible species, makes new conventional variety. genetic markers used.
- Mutagenesis: genes are mutated at random and desirable traits are selected. Makes new variety.
What is TILLING?
Targeting induced local lesions in genomes.
Generating mutations then looking at the genetics of them.
What methods are genes picked specifically and the mutations are not random?
Transgenic
Cisgenic
Gene editing
What is gene editing?
CrispR/Cas and a guide sequence is introduced.
Makes a transgenic plant with mutations, then offspring is selected that has mutations but no CrispR/Cas.
How do you distinguish the difference between plants with CrispR/Cas mutations and plants with conventional mutations?
Plants with conventional mutations will have additional unknown mutations.
However, conventional mutants are considered safer than gene edited mutants, even with unknown mutations.
What is transgenic GM?
Gene from sexually incompatible species is transformed into another species to form a new transgenic variety.
What is cisgenic GM?
Gene from sexually compatible species is transformed.
Forms transgenic variety
What current GM regulations are there in the UK?
Allows precision gene editing
What can be achieved by transgenetics?
- Altered gene expression
- Produce more/less of exisiting produce
- Produce new produce
- Altered development
How is a transgenic plant made?
- Transgene is produced (usually in E.coli)
- Transgene is introduced to plant (transformation), e.g. tissue culture
- Cells containing the transgene are selected
- Entire plant is regenerated from selected transformed cells
What is the structure of a trasgene?
- Promoter region:
When, what cell type, how much - Signal peptides:
- Coding region:
What, where in the cell
What are some commonly used promoters?
- Cauliflower mosaic virus
- cab protein
- Patatin
What is the typical construct of a transgenic plasmid?
Put in plant:
- Plant promoter and coding region
- Plant promoter and selectable marker
Not put in plant:
- Bacterium promoter and antibiotic resistance gene
- Origin of replication (OriT)
What are some methods of producing transgenic plants?
- Agrobacterium tumefaciens
- Electroporation of protoplasts
- Biolistics
What is Agrobacterium tumefaciens and what does it do and what genes does it synthesise?
Soil borne bacterium that naturally transmits bacterium DNA into the plant (TDNA) and contains the genes for mannopine and octopine synthesis.
How is agrobacterium tumefaciens used for GM?
- Genes for mannopine and octopine synthesis are replaces with transgenes.
- A leaf disc is incubated with the agrobacterium for gene transfer
- Leaf disc is placed on auxin and cytokinin to form a callus
- Callus is places on an antibiotic medium and non transformed cells die.
- Transformed cells are transferred to a medium with elevated cytokinins.
- Shoots form
- Shoots cut off and placed in an auxin rich medium
What are some alternatives to selectable markers?
- Antibiotic resistance
- Ability to metabolise unusual sugars
- Herbicide tolerance (the marker is the trait)
Why are there objections to GM crops?
- Playing God
- Unforeseen effects - safe?
- Allowing species boundaries to be crossed
- Technological approach to food production (dominated by a few companies, patents)
