2-precision plant breeding

Transgender breeding technology

• Easy methods for gene transfer to plat cells

• Genome modification by inserting foreign DNA

2 ways to transfer DNA into plant cells

• Biolistic transformation = particle bombardment

• Agrobacterial-mediated transformation = Ti-plasmid vector

Biological transformation = particle bombardment

1. DNA coating

   • Tiny metal particles (gold/tungsten) are coated with the desired DNA

2. Bombardement

   • The particles are shot at a high velocity into target cells using a gene gun

3. DNA intergration

   • Some of the DNA enters the nucleus and intergrates into the genome

4. Selection

   • Transformed cells are selected using markers and regenerated into the whole genome

Agrobacterium-mediated transformation = Ti-plasmid vector

1. Argobacterium & Ti plasmid

   • Naturally cause Gall disease by transferring parts of its Ti (tumour inducing) plasmid into plant cells

     • Scientists modify this plasmid by removing the tumour causing genes and inserting the gene of interest into its place with a marker

2. Infection

   • Plant tissues are infected with the engineered agrobacterium

3. T-DNA transfer

   • The gene in the T-DNA part of the plasmid is transferred into the plant genome

4. Selection & regeneration

   • Transferred cells are selected

     • Then regenerated into whole transgenic plants

Parts of a Ti-plasmid

• Left and right border

  • Mark the edges of the T-DNA

  • 25bp sequence

• Virulence region

  • Located outside the T-DNA

  • Encodes proteins that mediate T-DNA processing and transfer into the plant

• Opine region

  • Bacterium uses as nutrients

• Original of replication

  • Allows the plasmid to replicate in the bacterium

  • No benefit to host cells

Gene knockout

• Targets genes that code for undesirable traits