Pollen-mediated gene flow between paraquat-resistant and susceptible hare barley (Hordeum leporinum)

Abstract

Pollen movement between individuals can increase the rate of herbicide resistance evolution by spreading resistance alleles within or between populations and by facilitating the rapid accumulation of resistance alleles within individuals. This study investigated the level of pollen-mediated gene flow between paraquat-resistant and paraquat-susceptible populations of the self-pollinated weed species hare barley. The experiment was conducted in both directions, from resistant to susceptible and susceptible to resistant, across 2 yr. To maximize the potential for pollen flow, individual plants were grown in a single pot. The level of gene flow was similar across years and between genotypes. The level of pollen-mediated gene flow ranged from 0.06 to 0.15%. Gene flow from resistant to susceptible plants was confirmed by demonstrating segregation for resistance in the progeny of suspected crosses. This study suggests that pollen-mediated gene flow will occur in this species at frequencies less than 0.16% and could assist the accumulation of resistance alleles within a population. These low levels of gene flow through pollen movement suggest that cross-pollination over larger distances would be unlikely and pollen movement probably does not contribute to gene flow between populations.

Reducing the Risks of Herbicide Resistance: Best Management Practices and Recommendations

“…The assessment that herbicide-resistance management strategies will be unsuccessful is based on the belief that herbicide resistance in weeds occurs randomly and cannot be contained. Not only can resistance traits be moved through seed dispersal by natural elements (e.g., water, wind, and fauna) and agricultural equipment, but they can also be transferred through pollen movement (Busi et al 2008;Hidayat et al 2006;Murray et al 2002;Sosnoskie et al 2009). Transfer of herbicide-resistance genes among weed populations through pollen or seed movement has significant implications for resistance prevention and management.…”

Pollen-Mediated Dispersal of Glyphosate-Resistance in Palmer Amaranth under Field Conditions

“…Even if a competing pollen source affected our evaluation of gene flow, the donor parents were a minimum of 300 to 600 m distant from the study site. Pollen movement can increase the speed with which herbicide resistance develops in a weed population if the rate of outcrossing exceeds the rate of natural genetic mutation (Hidayat et al 2006;Jasieniuk et al 1996). In 2005, GR palmer amaranth was confirmed in only one county in Georgia; as of 2011, 65 counties in the state were infested to some degree with the GR biotype.…”

ISSR variation within and among wild Brassica juncea populations: implication for herbicide resistance evolution

“…Secondly, pollen movement might play a part in local gene movement to accelerate resistance evolution (Rieseberg and Burke 2001). Although the frequency of gene flow in self-pollinating species was estimated from 10 -5 to 10 -6 for a monodominant gene, the rate of gene flow could be fastened under herbicide application (Hidayat et al 2006). Gene flow can introduce resistance alleles from GM crops into weed species, a risk of resistant spread in weed would present itself.…”