Investigating the origins and evolution of a glyphosate-resistant weed invasion in South America

• Autores: Gaines, Todd A; Slavov, Gancho; Hughes, David; Kupper, Anita; Sparks, Crystal; Oliva, Julian; Vila Aiub, Martin Miguel; García, Alejandro Marcelo; Merotto, Aldo; Neve, Paul
• Año de publicación: 2021
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: AMARANTHUS PALMERI; HERBICIDE RESISTANCE; PALMER AMARANTH; POPULATION GENOMICS; RAD-SEQ
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

The global invasion, and subsequent spread and evolution of weeds provides unique opportunities to address fundamental questions in evolutionary and invasion ecology. Amaranthus palmeri is a widespread glyphosate-resistant (GR) weed in the USA. Since 2015, GR populations of A. palmeri have been confirmed in South America, raising questions about introduction pathways and the importance of pre- vs. post-invasion evolution of GR traits. We used RAD-sequencing genotyping to characterize genetic structure of populations from Brazil, Argentina, Uruguay and the USA. We also quantified gene copy number of the glyphosate target, 5-enolpyruvyl-3-shikimate phosphate synthase (EPSPS), and the presence of an extrachromosomal circular DNA (eccDNA) replicon known to confer glyphosate resistance in USA populations. Populations in Brazil, Argentina and Uruguay were only weakly differentiated (pairwise FST ≤0.043) in comparison to USA populations (mean pairwise FST =0.161, range =0.068–0.258), suggesting a single major invasion event. However, elevated EPSPS copy number and the EPSPS replicon were identified in all populations from Brazil and Uruguay, but only in a single Argentinean population. These observations are consistent with independent in situ evolution of glyphosate resistance in Argentina, followed by some limited recent migration of the eccDNA-based mechanism from Brazil to Argentina. Taken together, our results are consistent with an initial introduction of A. palmeri into South America sometime before the 1980s, and local evolution of GR in Argentina, followed by a secondary invasion of GR A. palmeri with the unique eccDNA-based mechanism from the USA into Brazil and Uruguay during the 2010s.
Fil: Gaines, Todd A. State University of Colorado - Fort Collins; Estados Unidos
Fil: Slavov, Gancho. No especifíca;
Fil: Hughes, David. No especifíca;
Fil: Kupper, Anita. State University of Colorado - Fort Collins; Estados Unidos
Fil: Sparks, Crystal. State University of Colorado - Fort Collins; Estados Unidos
Fil: Oliva, Julian. Universidad Católica de Córdoba; Argentina
Fil: 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. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina
Fil: García, Alejandro Marcelo. Instituto Nacional de Tecnología Agropecuaria; Argentina
Fil: Merotto, Aldo. Universidade Federal do Rio Grande do Sul; Brasil
Fil: Neve, Paul. No especifíca;