Abstract
The genus Lolium has shown a high tendency to evolve resistance to herbicides. Considering the high level of allogamy of L. perenne and the importance of the wind as an agent for pollen dispersion, the aim of this work was to assess and quantify the effective glyphosate-resistant gene flow by pollen in L. perenne under field conditions. Pollen-mediated gene flow from glyphosate-resistant to -susceptible plants was studied using a donor–receptor design. The results indicate that the effective gene flow reached trap plants distanced ≤35 m downwind from the source of pollen. The progeny of receptor plants growing 0 m from the pollen donors showed 13% of individuals with low glyphosate sensitivity. This represents a seven-fold increase in the frequency of glyphosate-resistant individuals found in the progeny of plants isolated during the flowering period (negative control). Similarly, the progenies of plants grown at 15 and 25 m from the source of glyphosate resistance showed an increase in the frequency of resistant plants by about four- and two-fold, respectively. When the receptor plants were located at >35 m, no glyphosate-resistant plants were detected in their progenies. Management should aim for prevention or delay of flowering of glyphosate-resistant plants.
Highlights
IntroductionAround 500 cases of herbicide-resistant weed populations have been reported [2]
The development of herbicide resistance in a weed population is an evolutionary process [1].Until now, around 500 cases of herbicide-resistant weed populations have been reported [2].Among these, the genus Lolium has shown high tendency to evolve herbicide resistance, and it includes species of the more troublesome cases of resistance in the world [2,3,4,5,6,7].Two requisites are necessary for the evolution of resistance to herbicides in a weed population: the existence of genetic variation for resistance, and the selection pressure imposed by the use of a herbicide [8]
The first condition could be generated by spontaneous mutations [9]; gene flow through dispersal of pollen or seed from resistant weed populations can provide a source of variation for resistance in previously susceptible populations
Summary
Around 500 cases of herbicide-resistant weed populations have been reported [2]. Two requisites are necessary for the evolution of resistance to herbicides in a weed population: the existence of genetic variation for resistance, and the selection pressure imposed by the use of a herbicide [8]. The first condition could be generated by spontaneous mutations [9]; gene flow through dispersal of pollen or seed from resistant weed populations can provide a source of variation for resistance in previously susceptible populations. Gene flow rates are generally higher than mutation rates, the time required to reach a high level of resistance is greatly reduced through gene flow [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
