Gene Flow from Herbicide-Resistant Crops to Wild Relatives

Abstract Pollen-mediated gene flow (PMGF) refers to the transfer of genetic information (alleles) from one plant to another compatible plant. With the evolution of herbicide-resistant (HR) weeds, PMGF plays an important role in the transfer of resistance alleles from HR to susceptible weeds; however, little attention is given to this topic. The objective of this work was to review reproductive biology, PMGF studies, and interspecific hybridization, as well as potential for herbicide resistance alleles to transfer in the economically important broadleaf weeds including common lambsquarters, giant ragweed, horseweed, kochia, Palmer amaranth, and waterhemp. The PMGF studies involving these species reveal that transfer of herbicide resistance alleles routinely occurs under field conditions and is influenced by several factors, such as reproductive biology, environment, and production practices. Interspecific hybridization studies within Amaranthus and Ambrosia spp. show that herbicide resistance allele transfer is possible between species of the same genus but at relatively low levels. The widespread occurrence of HR weed populations and high genetic diversity is at least partly due to PMGF, particularly in dioecious species such as Palmer amaranth and waterhemp compared with monoecious species such as common lambsquarters and horseweed. Prolific pollen production in giant ragweed contributes to PMGF. Kochia, a wind-pollinated species can efficiently disseminate herbicide resistance alleles via both PMGF and tumbleweed seed dispersal, resulting in widespread occurrence of multiple HR kochia populations. The findings from this review verify that intra- and interspecific gene flow can occur and, even at a low rate, could contribute to the rapid spread of herbicide resistance alleles. More research is needed to determine the role of PMGF in transferring multiple herbicide resistance alleles at the landscape level.

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Assessing the Impact of Pollen-mediated Gene Flow from GM Herbicide Tolerant Brassica Napus into Common Wild Relatives in Ireland

Biology & Environment Proceedings of the Royal Irish Academy ◽

10.3318/bioe.2012.12 ◽

2012 ◽

Vol 112 (3) ◽

pp. 257-266 ◽

Cited By ~ 2

Author(s):

Marcus J. Collier ◽

Ewen Mullins

Keyword(s):

Gene Flow ◽

Brassica Napus ◽

Wild Relatives ◽

Herbicide Tolerant ◽

The Impact

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Transfer of resistance alleles from herbicide-resistant to susceptible grass weeds via pollen-mediated gene flow

Weed Technology ◽

10.1017/wet.2021.82 ◽

2021 ◽

pp. 1-51

Author(s):

Amit J. Jhala ◽

Hugh J. Beckie ◽

Carol Mallory-Smith ◽

Marie Jasieniuk ◽

Roberto Busi ◽

...

Keyword(s):

Gene Flow ◽

Herbicide Resistance ◽

Creeping Bentgrass ◽

Agricultural Landscapes ◽

Italian Ryegrass ◽

Weed Species ◽

Herbicide Resistant ◽

Wild Oats ◽

Rigid Ryegrass ◽

Grass Weed

Abstract The objective of this paper was to review the reproductive biology, herbicide-resistant (HR) biotypes, pollen-mediated gene flow (PMGF), and potential for transfer of alleles from HR to susceptible grass weeds including barnyardgrass, creeping bentgrass, Italian ryegrass, johnsongrass, rigid (annual) ryegrass, and wild oats. The widespread occurrence of HR grass weeds is at least partly due to PMGF, particularly in obligate outcrossing species such as rigid ryegrass. Creeping bentgrass, a wind-pollinated turfgrass species, can efficiently disseminate herbicide resistance alleles via PMGF and movement of seeds and stolons. The genus Agrostis contains about 200 species, many of which are sexually compatible and produce naturally occurring hybrids as well as producing hybrids with species in the genus Polypogon. The self-incompatibility, extremely high outcrossing rate, and wind pollination in Italian ryegrass clearly point to PMGF as a major mechanism by which herbicide resistance alleles can spread across agricultural landscapes, resulting in abundant genetic variation within populations and low genetic differentiation among populations. Italian ryegrass can readily hybridize with perennial ryegrass and rigid ryegrass due to their similarity in chromosome numbers (2n=14), resulting in interspecific gene exchange. Johnsongrass, barnyardgrass, and wild oats are self-pollinated species, so the potential for PMGF is relatively low and limited to short distances; however, seeds can easily shatter upon maturity before crop harvest, leading to wider dispersal. The occurrence of PMGF in reviewed grass weed species, even at a low rate is greater than that of spontaneous mutations conferring herbicide resistance in weeds and thus can contribute to the spread of herbicide resistance alleles. This review indicates that the transfer of herbicide resistance alleles occurs under field conditions at varying levels depending on the grass weed species.

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Modeling gene flow from genetically modified plants.

10.1079/9781789247480.0007 ◽

2021 ◽

pp. 103-117

Author(s):

Wei Wei ◽

Jun-Ming Wang ◽

Xiang-Cheng Mi ◽

Yan-Da Li ◽

Yan-Ming Zhu

Keyword(s):

Gene Flow ◽

Genetically Modified ◽

Predictive Ability ◽

Crop Wild Relatives ◽

Gm Crops ◽

Wild Plants ◽

Experimental Conditions ◽

Flow Models ◽

Herbicide Resistant ◽

Gm Plants

Abstract Gene flow from genetically modified (GM) plants is concerning because of its ecological risks. In modeling studies, these risks may be reduced by altering crop management while taking environmental conditions into account. Gene flow modeling should consider many field aspects, both biological and physical. For example, empirical statistical models deduced from experimental data simulate gene flow well only under limited conditions (similar to experimental conditions). Mechanistic models, however, offer a potentially greater predictive ability. Gene flow models from GM crops to non-GM crops are used to simulate field conditions and minimize the adventitious presence of transgenes to meet certain threshold levels. These models can be adapted to simulate gene flow from GM crops to crop wild relatives using parameters of sexual compatibility and growth characteristics of the wild plants. Currently, modeling gene flow from herbicide-resistant weeds has become very important in light of the increased application of herbicides and widely evolved resistance in weeds.

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Pollen-Mediated Gene Flow of Sulfonylurea-Resistant Kochia (Kochia scoparia)

Weed Science ◽

10.1017/s0043174500080887 ◽

1995 ◽

Vol 43 (1) ◽

pp. 95-102 ◽

Cited By ~ 60

Author(s):

George P. Stallings ◽

Donald C. Thill ◽

Carol A. Mallory-Smith ◽

Bahman Shafii

Keyword(s):

Gene Flow ◽

Soil Temperature ◽

Wind Direction ◽

Spring Barley ◽

Growing Season ◽

Sulfonylurea Herbicide ◽

Kochia Scoparia ◽

Herbicide Resistant ◽

Resistant Trait ◽

Plot Design

The movement of sulfonylurea herbicide-resistant (R) kochia pollen was investigated in a spring barley field near Moscow, ID, using a Nelder plot design in 1991 and 1992. Each 61 m diameter plot had 16 rays spaced 22.5° apart and contained 211 kochia plants. There were 12 susceptible (S) plants and one R plant along each ray. The R and S plants were 1.5 m and 3.0 to 30.5 m from the center of the plot, respectively. Wind direction and speed in the 16 vectors, air and soil temperature, and rainfall were monitored continuously. Mature kochia seed was collected from individual plants, planted in the greenhouse, and sprayed with chlorsulfuron to test for resistant F1progeny. Results from the 2-yr study showed outcrossing of R pollen onto S plants at rates up to 13.1% per plant 1.5 m from the R plants and declining to 1.4% per plant or less 29 m from the R plants. At least 35% of the total R x S crosses occurred in the direction of prevailing southeastward winds. Predicted percentages of R x S crosses per plant ranged from 0.16 to 1.29 at 1.5 m, and 0.00 to 0.06% at 29 m. Thus, resistant kochia pollen can spread the sulfonylurea-resistant trait at least 30 m during each growing season.

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Gene Flow Between Cultivated Plants and Their Wild Relatives

Springer Climate - Combating Global Warming ◽

10.1007/978-3-030-23037-1_10 ◽

2019 ◽

pp. 49-52 ◽

Cited By ~ 1

Author(s):

Kodoth Prabhakaran Nair

Keyword(s):

Gene Flow ◽

Wild Relatives ◽

Cultivated Plants

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Voter Model and Biased Voter Model in Heterogeneous Environments

Journal of Applied Probability ◽

10.1017/s0021900200003429 ◽

2007 ◽

Vol 44 (03) ◽

pp. 770-787

Author(s):

N. Lanchier ◽

C. Neuhauser

Keyword(s):

Gene Flow ◽

Pollen Dispersal ◽

Transgenic Crops ◽

Wild Relatives ◽

Voter Model ◽

Wild Plants ◽

Transgenic Crop ◽

Heterogeneous Environments ◽

Wild Type ◽

Type Gene

With the rapid adoption of transgenic crops, gene flow from transgenic crops to wild relatives through pollen dispersal is of significant concern and warrants both empirical and theoretical studies to assess the risk of introduction of transgenes into wild populations. We propose to use the (biased) voter model in a heterogeneous environment to investigate the effects of recurrent gene flow from transgenic crop to wild relatives. The model is defined on the d-dimensional integer lattice that is divided into two parts, Δ and Z d \ Δ. Individuals carrying the transgene and individuals carrying the wild type gene compete according to the evolution rules of a (biased) voter model on Z d \ Δ, while the process is conditioned to have only individuals carrying the transgene on Δ. Our main findings suggest that unless transgenes confer increased fitness in wild relatives, introgression of transgenes into populations of wild plants is slow and may even be reversible without intervention. Our study also addresses the effects of different spatial planting patterns of transgenic crops on the rate of introgression.

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