Modeling pollen-mediated gene flow from glyphosate-resistant to -susceptible giant ragweed (Ambrosia trifida L.) under field conditions

Amit J. Jhala,Zahoor A. Ganie

doi:10.1038/s41598-017-16737-z

Abstract

A field experiment was conducted to quantify pollen mediated gene flow (PMGF) from glyphosate-resistant (GR) to glyphosate-susceptible (GS) giant ragweed under simulated field conditions using glyphosate resistance as a selective marker. Field experiments were conducted in a concentric design with the GR giant ragweed pollen source planted in the center and GS giant ragweed pollen receptors surrounding the center in eight directional blocks at specified distances (between 0.1 and 35 m in cardinal and ordinal directions; and additional 50 m for ordinal directions). Seeds of GS giant ragweed were harvested from the pollen receptor blocks and a total of 100,938 giant ragweed plants were screened with glyphosate applied at 2,520 g ae ha−1 and 16,813 plants confirmed resistant. The frequency of PMGF was fit to a double exponential decay model selected by information-theoretic criteria. The highest frequency of gene flow (0.43 to 0.60) was observed at ≤0.5 m from the pollen source and reduced rapidly with increasing distances; however, gene flow (0.03 to 0.04) was detected up to 50 m. The correlation between PMGF and wind parameters was inconsistent in magnitude, direction, and years.

Highlights

Gene flow is the natural process of disseminating genetic information from one breeding population to another related population or between the closely related species[1]
pollen mediated gene flow (PMGF) from GM crops to conventional crops or their weedy and wild relatives has been extensively studied to understand the consequences of introducing domesticated alleles or transgenes in natural populations[5,11,37,38,39,40,41]; more scientific information is needed to understand the dissemination of herbicide resistant traits between biotypes of the same weed species or closely related species for improved management strategies[42,43,44,45,46,47]
The delayed flowering at distances ≥10 m from the pollen source was possibly due to lower plant density and minimal competition for resources resulting in vigorous vegetative growth and a delay in the transition to the reproductive phase, flowering synchrony was not affected

Summary

Introduction

Gene flow is the natural process of disseminating genetic information from one breeding population to another (usually) related population or between the closely related species[1]. PMGF from GM crops to conventional crops or their weedy and wild relatives has been extensively studied to understand the consequences of introducing domesticated alleles or transgenes in natural populations[5,11,37,38,39,40,41]; more scientific information is needed to understand the dissemination of herbicide resistant traits between biotypes of the same weed species or closely related species for improved management strategies[42,43,44,45,46,47]. Giant ragweed is a competitive summer annual broadleaf weed found throughout the United States and southern Canada[50,51,52] It is a monoecious species, meaning that separate male and female flowers are present on the same plant.

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Conclusion