2,4-D and dicamba resistance mechanisms in wild radish: subtle, complex and population specific?

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Abstract

Background and Aims: Resistance to synthetic auxin herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) is increasing in weed populations worldwide, which is of concern given the recent introduction of synthetic auxin-resistant transgenic crops. Due to the complex mode of action of the auxinic herbicides, the mechanisms of evolved resistance remain largely uncharacterized. The aims of this study were to assess the level of diversity in resistance mechanisms in 11 populations of the problem weed Raphanus raphanistrum, and to use a high-throughput, whole-genome transcriptomic analysis on one resistant and one susceptible population to identify important changes in gene expression in response to 2,4-D.

Methods: Levels of 2,4-D and dicamba (3,6-dichloro-2-methoxybenzoic acid) resistance were quantified in a dose-response study and the populations were further screened for auxin selectivity, 2,4-D translocation and metabolism, expression of key 2,4-D-responsive genes and activation of the mitogen-activated proein kinase (MAPK) pathway. Potential links between resistance levels and mechanisms were assessed using correlation analysis.

Key Results: The transcriptomic study revealed early deployment of the plant defence response in the 2,4-D-treated resistant population, and there was a corresponding positive relationship between auxinic herbicide resistance and constitutive MAPK phosphorylation across all populations. Populations with shoot-wide translocation of 2,4-D had similar resistance levels to those with restricted translocation, suggesting that reduced translocation may not be as strong a resistance mechanism as originally thought. Differences in auxin selectivity between populations point to the likelihood of different resistance-conferring alterations in auxin signalling and/or perception in the different populations.

Conclusions: 2,4-D resistance in wild radish appears to result from subtly different auxin signalling alterations in different populations, supplemented by an enhanced defence response and, in some cases, reduced 2,4-D translocation. This study highlights the dangers of applying knowledge generated from a few populations of a weed species to the species as a whole.

Original languageEnglish
Pages (from-to)627-640
Number of pages14
JournalAnnals of Botany
Volume122
Issue number4
DOIs
Publication statusPublished - 24 Sep 2018

Fingerprint

dicamba
radishes
resistance mechanisms
2,4-D
auxins
weeds
transcriptomics
phosphotransferases (kinases)
herbicides
Raphanus raphanistrum
acid tolerance
herbicide resistance
at-risk population
dose response
mechanism of action
phosphorylation
genetically modified organisms
gene expression

Cite this

@article{f8cf0367a9454f31b239897b94c10e6c,
title = "2,4-D and dicamba resistance mechanisms in wild radish: subtle, complex and population specific?",
abstract = "Background and Aims: Resistance to synthetic auxin herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) is increasing in weed populations worldwide, which is of concern given the recent introduction of synthetic auxin-resistant transgenic crops. Due to the complex mode of action of the auxinic herbicides, the mechanisms of evolved resistance remain largely uncharacterized. The aims of this study were to assess the level of diversity in resistance mechanisms in 11 populations of the problem weed Raphanus raphanistrum, and to use a high-throughput, whole-genome transcriptomic analysis on one resistant and one susceptible population to identify important changes in gene expression in response to 2,4-D.Methods: Levels of 2,4-D and dicamba (3,6-dichloro-2-methoxybenzoic acid) resistance were quantified in a dose-response study and the populations were further screened for auxin selectivity, 2,4-D translocation and metabolism, expression of key 2,4-D-responsive genes and activation of the mitogen-activated proein kinase (MAPK) pathway. Potential links between resistance levels and mechanisms were assessed using correlation analysis.Key Results: The transcriptomic study revealed early deployment of the plant defence response in the 2,4-D-treated resistant population, and there was a corresponding positive relationship between auxinic herbicide resistance and constitutive MAPK phosphorylation across all populations. Populations with shoot-wide translocation of 2,4-D had similar resistance levels to those with restricted translocation, suggesting that reduced translocation may not be as strong a resistance mechanism as originally thought. Differences in auxin selectivity between populations point to the likelihood of different resistance-conferring alterations in auxin signalling and/or perception in the different populations.Conclusions: 2,4-D resistance in wild radish appears to result from subtly different auxin signalling alterations in different populations, supplemented by an enhanced defence response and, in some cases, reduced 2,4-D translocation. This study highlights the dangers of applying knowledge generated from a few populations of a weed species to the species as a whole.",
author = "Goggin, {Danica E.} and Parwinder Kaur and Owen, {Mechelle J.} and Powles, {Stephen B.}",
year = "2018",
month = "9",
day = "24",
doi = "10.1093/aob/mcy097",
language = "English",
volume = "122",
pages = "627--640",
journal = "Annals of Botany",
issn = "0305-7364",
publisher = "OXFORD UNIV PRESS UNITED KINGDOM",
number = "4",

}

TY - JOUR

T1 - 2,4-D and dicamba resistance mechanisms in wild radish

T2 - subtle, complex and population specific?

AU - Goggin, Danica E.

AU - Kaur, Parwinder

AU - Owen, Mechelle J.

AU - Powles, Stephen B.

PY - 2018/9/24

Y1 - 2018/9/24

N2 - Background and Aims: Resistance to synthetic auxin herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) is increasing in weed populations worldwide, which is of concern given the recent introduction of synthetic auxin-resistant transgenic crops. Due to the complex mode of action of the auxinic herbicides, the mechanisms of evolved resistance remain largely uncharacterized. The aims of this study were to assess the level of diversity in resistance mechanisms in 11 populations of the problem weed Raphanus raphanistrum, and to use a high-throughput, whole-genome transcriptomic analysis on one resistant and one susceptible population to identify important changes in gene expression in response to 2,4-D.Methods: Levels of 2,4-D and dicamba (3,6-dichloro-2-methoxybenzoic acid) resistance were quantified in a dose-response study and the populations were further screened for auxin selectivity, 2,4-D translocation and metabolism, expression of key 2,4-D-responsive genes and activation of the mitogen-activated proein kinase (MAPK) pathway. Potential links between resistance levels and mechanisms were assessed using correlation analysis.Key Results: The transcriptomic study revealed early deployment of the plant defence response in the 2,4-D-treated resistant population, and there was a corresponding positive relationship between auxinic herbicide resistance and constitutive MAPK phosphorylation across all populations. Populations with shoot-wide translocation of 2,4-D had similar resistance levels to those with restricted translocation, suggesting that reduced translocation may not be as strong a resistance mechanism as originally thought. Differences in auxin selectivity between populations point to the likelihood of different resistance-conferring alterations in auxin signalling and/or perception in the different populations.Conclusions: 2,4-D resistance in wild radish appears to result from subtly different auxin signalling alterations in different populations, supplemented by an enhanced defence response and, in some cases, reduced 2,4-D translocation. This study highlights the dangers of applying knowledge generated from a few populations of a weed species to the species as a whole.

AB - Background and Aims: Resistance to synthetic auxin herbicides such as 2,4-dichlorophenoxyacetic acid (2,4-D) is increasing in weed populations worldwide, which is of concern given the recent introduction of synthetic auxin-resistant transgenic crops. Due to the complex mode of action of the auxinic herbicides, the mechanisms of evolved resistance remain largely uncharacterized. The aims of this study were to assess the level of diversity in resistance mechanisms in 11 populations of the problem weed Raphanus raphanistrum, and to use a high-throughput, whole-genome transcriptomic analysis on one resistant and one susceptible population to identify important changes in gene expression in response to 2,4-D.Methods: Levels of 2,4-D and dicamba (3,6-dichloro-2-methoxybenzoic acid) resistance were quantified in a dose-response study and the populations were further screened for auxin selectivity, 2,4-D translocation and metabolism, expression of key 2,4-D-responsive genes and activation of the mitogen-activated proein kinase (MAPK) pathway. Potential links between resistance levels and mechanisms were assessed using correlation analysis.Key Results: The transcriptomic study revealed early deployment of the plant defence response in the 2,4-D-treated resistant population, and there was a corresponding positive relationship between auxinic herbicide resistance and constitutive MAPK phosphorylation across all populations. Populations with shoot-wide translocation of 2,4-D had similar resistance levels to those with restricted translocation, suggesting that reduced translocation may not be as strong a resistance mechanism as originally thought. Differences in auxin selectivity between populations point to the likelihood of different resistance-conferring alterations in auxin signalling and/or perception in the different populations.Conclusions: 2,4-D resistance in wild radish appears to result from subtly different auxin signalling alterations in different populations, supplemented by an enhanced defence response and, in some cases, reduced 2,4-D translocation. This study highlights the dangers of applying knowledge generated from a few populations of a weed species to the species as a whole.

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U2 - 10.1093/aob/mcy097

DO - 10.1093/aob/mcy097

M3 - Article

VL - 122

SP - 627

EP - 640

JO - Annals of Botany

JF - Annals of Botany

SN - 0305-7364

IS - 4

ER -