Making GM Plants

Question 1

What are GMO / transgenic plants?

Answer 1

Plants made by recombinant DNA technology

Question 2

What are examples of conventional breeding?

Answer 2

• 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.

Question 3

What is TILLING?

Answer 3

Targeting induced local lesions in genomes.
Generating mutations then looking at the genetics of them.

Question 4

What methods are genes picked specifically and the mutations are not random?

Answer 4

Transgenic
Cisgenic
Gene editing

Question 5

What is gene editing?

Answer 5

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.

Question 6

How do you distinguish the difference between plants with CrispR/Cas mutations and plants with conventional mutations?

Answer 6

Plants with conventional mutations will have additional unknown mutations.
However, conventional mutants are considered safer than gene edited mutants, even with unknown mutations.

Question 7

What is transgenic GM?

Answer 7

Gene from sexually incompatible species is transformed into another species to form a new transgenic variety.

Question 8

What is cisgenic GM?

Answer 8

Gene from sexually compatible species is transformed.
Forms transgenic variety

Question 9

What current GM regulations are there in the UK?

Answer 9

Allows precision gene editing

Question 10

What can be achieved by transgenetics?

Answer 10

• Altered gene expression
• Produce more/less of exisiting produce
• Produce new produce
• Altered development

Question 11

How is a transgenic plant made?

Answer 11

• 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

Question 12

What is the structure of a trasgene?

Answer 12

• Promoter region:
  When, what cell type, how much
• Signal peptides:
• Coding region:
  What, where in the cell

Question 13

What are some commonly used promoters?

Answer 13

• Cauliflower mosaic virus
• cab protein
• Patatin

Question 14

What is the typical construct of a transgenic plasmid?

Answer 14

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)

Question 15

What are some methods of producing transgenic plants?

Answer 15

• Agrobacterium tumefaciens
• Electroporation of protoplasts
• Biolistics

Question 16

What is Agrobacterium tumefaciens and what does it do and what genes does it synthesise?

Answer 16

Soil borne bacterium that naturally transmits bacterium DNA into the plant (TDNA) and contains the genes for mannopine and octopine synthesis.

Question 17

How is agrobacterium tumefaciens used for GM?

Answer 17

• 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

Question 18

What are some alternatives to selectable markers?

Answer 18

• Antibiotic resistance
• Ability to metabolise unusual sugars
• Herbicide tolerance (the marker is the trait)

Question 19

Why are there objections to GM crops?

Answer 19

• Playing God
• Unforeseen effects - safe?
• Allowing species boundaries to be crossed
• Technological approach to food production (dominated by a few companies, patents)