Biased allele transmission for herbicide resistance: a conditional gene drive.

Herbicide application to plants heterozygous for herbicide resistance results in distorted segregation favoring resistant allele transmission resulting in a conditional gene drive. Brassica napus plants heterozygous for an allele conferring sulfonylurea resistance at a single locus exhibit normal Mendelian inheritance. However, following application of the herbicide, highly distorted segregation of herbicide resistance occurs among progeny. Screening progeny from controlled crosses demonstrated that the herbicide imposes in planta gametic selection against pollen and ovules with the recessive allele for herbicide susceptibility, as well as embryonic selection against embryos homozygous for the susceptible allele. Such inducible biased inheritance represents a conditional form of allele transmission following herbicide application and mimics a natural gene drive. We postulate that natural gene drives are common in plant populations and can operate in a conditional manner resulting in non-Mendelian inheritance in response to abiotic and biotic stresses.