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1 October 2016 Pollen- and Seed-Mediated Gene Flow in Kochia ( Kochia scoparia)
Hugh J. Beckie, Robert E. Blackshaw, Linda M. Hall, Eric N. Johnson
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Efficient natural dispersal of herbicide-resistance alleles via seed and pollen can markedly accelerate the incidence of herbicide-resistant weed populations across an agroecoregion. Studies were conducted in western Canada in 2014 and 2015 to investigate pollen- and seed-mediated gene flow in kochia. Pollen-mediated gene flow (PMGF) from glyphosate-resistant (GR) to non-GR kochia was quantified in a field trial (hub and spoke design) at Saskatoon, Saskatchewan. Seed-mediated gene flow of acetolactate synthase (ALS) inhibitor-resistant kochia as a function of tumbleweed speed and distance was estimated in cereal stubble fields at Lethbridge, Alberta and Scott, Saskatchewan. Regression analysis indicated that outcrossing from GR to adjacent non-GR kochia ranged from 5.3 to 7.5%, declining exponentially to 0.1 to 0.4% at 96 m distance. However, PMGF was significantly influenced by prevailing wind direction during pollination (maximum of 11 to 17% outcrossing down-wind). Seed dropped by tumbleweeds varied with distance and plant speed, approaching 90% or more (ca. 100,000 seeds or more) at distances of up to 1,000 m and plant speeds of up to 300 cm s−1. This study highlights the efficient proximal (pollen) and distal (seed) gene movement of this important GR weed.

Nomenclature: Glyphosate; kochia, Kochia scoparia (L.) Schrad., KCHSC.

Hugh J. Beckie, Robert E. Blackshaw, Linda M. Hall, and Eric N. Johnson "Pollen- and Seed-Mediated Gene Flow in Kochia ( Kochia scoparia)," Weed Science 64(4), 624-633, (1 October 2016).
Received: 8 March 2016; Accepted: 1 May 2016; Published: 1 October 2016
ALS-inhibitor resistance
Glyphosate resistance
Herbicide resistance
multiple resistance
pollen flow
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