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Glyphosate resistance in Ambrosia trifida: Part 1. Novel rapid cell death response to glyphosate

Author:
Van Horn, Christopher R, Moretti, Marcelo L, Robertson, Renae R, Segobye, Kabelo, Weller, Stephen C, Young, Bryan G, Johnson, William G, Schulz, Burkhard, Green, Amanda C, Jeffery, Taylor, Lespérance, Mackenzie A, Tardif, François J, Sikkema, Peter H, Hall, J Christopher, McLean, Michael D, Lawton, Mark B, Sammons, R Douglas, Wang, Dafu, Westra, Philip, Gaines, Todd A
Source:
Pest management science 2018 v.74 no.5 pp. 1071-1078
ISSN:
1526-498X
Subject:
3-phosphoshikimate 1-carboxyvinyltransferase, Ambrosia trifida, cell death, glyphosate, herbicide resistance, mutation, phenotype, Midwestern United States, Ontario
Abstract:
BACKGROUND: Glyphosate‐resistant (GR) Ambrosia trifida is now present in the midwestern United States and in southwestern Ontario, Canada. Two distinct GR phenotypes are known, including a rapid response (GR RR) phenotype, which exhibits cell death within hours after treatment, and a non‐rapid response (GR NRR) phenotype. The mechanisms of resistance in both GR RR and GR NRR remain unknown. Here, we present a description of the RR phenotype and an investigation of target‐site mechanisms on multiple A. trifida accessions. RESULTS: Glyphosate resistance was confirmed in several accessions, and whole‐plant levels of resistance ranged from 2.3‐ to 7.5‐fold compared with glyphosate‐susceptible (GS) accessions. The two GR phenotypes displayed similar levels of resistance, despite having dramatically different phenotypic responses to glyphosate. Glyphosate resistance was not associated with mutations in EPSPS sequence, increased EPSPS copy number, EPSPS quantity, or EPSPS activity. CONCLUSION: These encompassing results suggest that resistance to glyphosate in these GR RR A. trifida accessions is not conferred by a target‐site resistance mechanism. © 2017 Society of Chemical Industry
Agid:
5920458