Gene flow from transgenic common beans expressing the bar gene

Area of Science:

• Agricultural Science
• Genetics
• Plant Breeding

Background:

• Gene flow is a significant concern for genetically modified (GM) crops, particularly regarding transgene containment.
• Understanding outcrossing rates in self-pollinated species like common beans is crucial for risk assessment.

Purpose of the Study:

• To quantify the occurrence and intensity of outcrossing in transgenic common bean (Phaseolus vulgaris) cultivars.
• To evaluate the potential for transgene flow from GM to conventional common bean varieties.

Main Methods:

• Field experiments were conducted in Brazil using transgenic common bean lines resistant to glufosinate ammonium and their conventional counterparts.
• Outcross rates were assessed using different experimental designs and locations over multiple years.
• Transgenic cultivars were used as pollen recipients, surrounded by conventional varieties to measure gene flow.

Main Results:

• Outcrossing rates were cultivar-dependent, with negligible gene flow observed (0.00741% in cv. Pérola, 0.0% in cv. Olathe Pinto).
• The majority of observed outcrossing occurred within a short distance (2.5 m) from the pollen source.
• Gene flow was minimal, indicating effective containment strategies may be feasible.

Conclusions:

• Transgenic common beans exhibit very low rates of outcrossing, suggesting a low risk of unintended transgene spread.
• Cultivar choice and spatial arrangement can influence gene flow, highlighting the importance of tailored management practices.
• The findings support the safe cultivation of glufosinate ammonium-resistant transgenic common beans.