In stage 2, why are bacteria cultured before the plant tissue is added?

• A. The bacteria divide / grow, producing many copies of desired gene / plasmid
• B. The bacteria change into plant cells
• C. The bacteria are killed by antibiotics immediately
• D. The bacteria become resistant to plant toxins

Answer: (A)

Amplifying the plasmid in bacteria to increase the amount of gene available for transfer is the idea behind this stage. Bacteria carrying the plasmid divide, producing many copies of the plasmid and the gene of interest. This ensures there is enough genetic material to improve the efficiency of transferring the gene into plant tissue during the subsequent transformation step. After the transformation, antibiotics are used to stop bacterial growth and to select for plant cells that have taken up the plasmid, rather than killing bacteria immediately before transfer. The other options don’t fit because bacteria don’t become plant cells, and the goal isn’t to make bacteria resistant to plant toxins at this stage.