Abstract:

Synthetic herbicides have been used globally to control weeds in major field crops. This has imposed a strong selection for any trait that enables plant populations to survive and reproduce in the presence of the herbicide. Herbicide resistance in weeds must be minimized because it is a major limiting factor to food security in global agriculture. This represents a huge challenge that will require great research efforts to develop control strategies as alternatives to the dominant and almost exclusive practice of weed control by herbicides. Weed scientists, plant ecologists and evolutionary biologists should join forces and work towards an improved and more integrated understanding of resistance across all scales. This approach will likely facilitate the design of innovative solutions to the global herbicide resistance challenge.

Author affiliation: Busi, Roberto. University of Western Australia. School of Plant Biology; Australia;

Author affiliation: Vila Aiub, Martin Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina; University of Western Australia. School of Plant Biology; Australia;

Author affiliation: Beckie, Hugh J.. Agriculture and Agri-Food Canada. Saskatoon Research Centre; Canadá;

Author affiliation: Gaines, Todd A.. University of Western Australia. School of Plant Biology; Australia;

Author affiliation: Goggin, Danica E.. University of Western Australia. School of Plant Biology; Australia;

Author affiliation: Kaundun, Shiv S.. Syngenta. Biology and Logistics; Reino Unido;

Author affiliation: Lacoste, Myrtille. University of Western Australia. School of Plant Biology; Australia;

Author affiliation: Neve, Paul. University of Warwick. School of Life Sciences; Reino Unido;

Author affiliation: Nissen, Scott J.. Colorado State University. Department of Bioagricultural Sciences and Pest Management; Estados Unidos de América;

Author affiliation: Norsworthy, Jason K.. University of Arkansas. Crop, Soil and Environmental Sciences Department (Weed Science); Estados Unidos de América;

Author affiliation: Renton, Michael. University of Western Australia. School of Plant Biology; Australia;

Author affiliation: Shaner, Dave L.. United States Department of Agriculture. Agricultural Research Service; Estados Unidos de América;

Author affiliation: Tranel, Patrick J.. University of Illinois. Department of Crop Science; Estados Unidos de América;

Author affiliation: Wright, Terry. Dow AgroSciences. Intellectual Property Portfolio Development; Estados Unidos de América;

Author affiliation: Yu, Quin. University of Western Australia. School of Plant Biology; Australia;

Author affiliation: Powles, Stephen B.. University of Western Australia. School of Plant Biology; Australia;

Abstract:

A 2,4-D-resistant tall waterhemp population (FS) from Nebraska was evaluated for resistance to other TIR1 auxin receptor herbicides and to herbicides having alternative mechanisms of action using greenhouse bioassays and genetic markers. Atrazine, imazethapyr, lactofen, mesotrione, glufosinate, and glyphosate were applied in a single-dose bioassay, and tissue was collected from marked plants for genetic analysis. The FS population was not injured by atrazine or by imazethapyr. Approximately 50% of the plants survived lactofen and were actively growing 28 d after treatment. The population was susceptible to mesotrione, glufosinate, and glyphosate. Ametryn, chlorimuron-ethyl, 2,4-D, aminocyclopyraclor, aminopyralid, and picloram were applied in dose - response studies. The FS population was sensitive to ametryn, and the Ser-264-Gly substitution in the D1 protein was not detected, suggesting the lack of response to atrazine is not due to a target-site mutation. The FS population exhibited less than 50% injury to chlorimuron-ethyl at application rates 20 times the labeled use rate. The Ser-653-Asn acetolactate synthase (ALS) substitution, which confers resistance to imidazolinone herbicides, was present in the FS population. However, this does not explain the lack of response to the sulfonylurea herbicide, chlorimuron-ethyl. Sequencing of a portion of the PPX2L gene did not show the ΔG210 mutation that confers resistance to protoporphyrinogen oxidase - inhibiting herbicides, suggesting that other factors were responsible for waterhemp survival after lactofen application. The FS population was confirmed to be at least 30-fold resistant to 2,4-D relative to the susceptible populations. In addition, it was at least 3-fold less sensitive to aminopyralid and picloram, two other TIR1 auxin receptor herbicides, than the 2,4-D-susceptible populations were. These data indicated that the FS population contains both target and non - target site mechanisms conferring resistance to herbicides spanning at least three mechanisms of action: TIR1 auxin receptors, ALS inhibitors, and photosystem II inhibitors.

Author affiliation: Crespo, Roberto Javier. University of Nebraska; Estados Unidos

Author affiliation: Wingeyer, Ana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Entre Ríos. Estación Experimental Agropecuaria Paraná; Argentina

Author affiliation: Kruger, Greg R.. University of Nebraska; Estados Unidos

Author affiliation: Riggins, Chance W.. University of Illinois at Urbana; Estados Unidos

Author affiliation: Tranel, Patrick J.. University of Illinois at Urbana; Estados Unidos

Author affiliation: Bernards, Mark L.. University of Nebraska; Estados Unidos

Abstract:

A 2,4-D-resistant tall waterhemp population (FS) from Nebraska was evaluated for resistance to other TIR1 auxin receptor herbicides and to herbicides having alternative mechanisms of action using greenhouse bioassays and genetic markers. Atrazine, imazethapyr, lactofen, mesotrione, glufosinate, and glyphosate were applied in a single-dose bioassay, and tissue was collected from marked plants for genetic analysis. The FS population was not injured by atrazine or by imazethapyr. Approximately 50% of the plants survived lactofen and were actively growing 28 d after treatment. The population was susceptible to mesotrione, glufosinate, and glyphosate. Ametryn, chlorimuron-ethyl, 2,4-D, aminocyclopyraclor, aminopyralid, and picloram were applied in dose–response studies. The FS population was sensitive to ametryn, and the Ser-264-Gly substitution in the D1 protein was not detected, suggesting the lack of response to atrazine is not due to a target-site mutation. The FS population exhibited less than 50% injury to chlorimuron-ethyl at application rates 20 times the labeled use rate. The Ser-653-Asn acetolactate synthase (ALS) substitution, which confers resistance to imidazolinone herbicides, was present in the FS population. However, this does not explain the lack of response to the sulfonylurea herbicide, chlorimuron-ethyl. Sequencing of a portion of the PPX2L gene did not show the ΔG210 mutation that confers resistance to protoporphyrinogen oxidase–inhibiting herbicides, suggesting that other factors were responsible for waterhemp survival after lactofen application. The FS population was confirmed to be at least 30-fold resistant to 2,4-D relative to the susceptible populations. In addition, it was at least 3-fold less sensitive to aminopyralid and picloram, two other TIR1 auxin receptor herbicides, than the 2,4-D-susceptible populations were. These data indicated that the FS population contains both target and non–target site mechanisms conferring resistance to herbicides spanning at least three mechanisms of action: TIR1 auxin receptors, ALS inhibitors, and photosystem II inhibitors.

EEA Paraná

Author affiliation: Crespo, Roberto J. University of Nebraska–Lincoln. Department of Agronomy and Horticulture; Estados Unidos

Author affiliation: Wingeyer, Ana Beatriz. INTA. Estación Experimental Agropecuaria Paraná; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Kruger, Greg R. University of Nebraska–Lincoln. West Central Research and Extension Center; Estados Unidos

Author affiliation: Riggins, Chance W. University of Illinois. Department of Crop Sciences; Estados Unidos

Author affiliation: Tranel, Patrick J. University of Illinois. Department of Crop Sciences; Estados Unidos

Author affiliation: Bernards, Mark L. University of Nebraska–Lincoln. Department of Agronomy and Horticulture; Estados Unidos