Tandem constructs to mitigate transgene persistence: tobacco as a model

Area of Science:

• Agricultural Science
• Genetics
• Ecology

Background:

• Transgenic crops can spread genes to wild relatives, increasing weediness.
• Current gene containment methods have low-frequency gene release (leakage).
• Transgene introgression requires mitigation strategies to prevent ecological disruption.

Purpose of the Study:

• To test transgenic mitigation (TM) as a strategy to prevent transgene spread.
• To evaluate the effectiveness of linked dwarfing genes in reducing crop weediness.
• To assess transgene containment in the absence of herbicide selection.

Main Methods:

• Engineered tobacco (Nicotiana tabacum) with a tandemly linked herbicide resistance gene (ahasR) and a dwarfing gene (Delta gai).
• Confirmed gene integration and stability across generations using polymerase chain reaction.
• Assessed competitive ability of transgenic vs. wild-type plants under varying spacings without herbicide.

Main Results:

• Transgenic mitigation (TM) plants exhibited reduced competitiveness and reproductive fitness compared to wild types.
• Dwarf transgenic plants showed high mortality when interplanted with wild types, especially at close spacings.
• Reproductive fitness of TM plants relative to wild types was a maximum of 17%.

Conclusions:

• Transgenic mitigation effectively suppresses gene introgression into wild relatives or volunteer crops.
• Linked deleterious genes reduce the weediness and invasiveness of transgenic offspring.
• This strategy maintains transgenes at low frequencies across generations, enhancing biosafety.