From tolerance to resistance: mechanisms governing the differential response to glyphosate in Chloris barbata

• Autor(a) principal: Bracamonte, Enzo
• Data de Publicação: 2018
• Outros Autores: Silveira, Hellen Martins da, Cruz, Ricardo Alcántara‐de la, Domínguez‐Valenzuela, José Alfredo, Cruz‐Hipolito, Hugo Enrique, Prado, Rafael De
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: https://doi.org/10.1002/ps.4874; http://www.locus.ufv.br/handle/123456789/19968
• topic: 5-enolpyruvylshikimate-3-phosphate synthase; Herbicide resistance; Impaired translocation; Pro106-Ser mutation; Purpletop chloris

Susceptibility and the mechanism (s) governing tolerance/resistance to glyphosate were characterized in two putative-glyphosate-resistant Chloris barbata populations (R1 and R2), collected in Persian lime orchards from Colima State, Mexico, comparing them with one non-treated population (referred to as S). Glyphosate doses required to reduce fresh weight or cause mortality by 50% were 4.2–6.4 times higher in resistant populations than in the S population. The S population accumulated 4.3 and 5.2 times more shikimate than the R2 and R1 popu- lations, respectively. There were no differences in 14 C-glyphosate uptake between R and S populations, but the R plants translo- cated at least 12% less herbicide to the rest of plant and roots 96 h after treatment. Insignificant amounts of glyphosate were metabolized to aminomethyl phosphonate and glyoxylate in both R and S plants. The 5-enolpyruvylshikimate-3-phosphate syn- thase gene of the R populations contained the Pro106-Ser mutation, giving them a resistance 12 (R2) and 14.7 (R1) times greater at target-site level compared with the S population. The Pro106-Ser mutation governs the resistance to glyphosate of the R1 and R2 C barbata populations, but the impaired translocation could contribute to the resistance. These results confirm the first case of glyphosate resistance evolved in this species.