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Non-Target-Site Resistance Mechanisms Endow Multiple Herbicide Resistance to Five Mechanisms of Action in Conyza bonariensis.

  • Palma-Bautista, Candelario1
  • Vázquez-García, José G1
  • Domínguez-Valenzuela, José Alfredo2
  • Ferreira Mendes, Kassio3
  • Alcántara de la Cruz, Ricardo4
  • Torra, Joel5
  • De Prado, Rafael1
  • 1 Department of Agricultural Chemistry, Edaphology and Microbiology, University of Cordoba, 14014 Córdoba, Spain. , (Spain)
  • 2 Departamento de Parasitología Agrícola, Universidad Autónoma Chapingo, 56230 Texcoco, México.
  • 3 Departamento de Agronomia, Universidade Federal de Viçosa, Viçosa 36570-900, Minas Gerais, Brazil. , (Brazil)
  • 4 Centro de Ciências da Natureza, Universidade Federal de São Carlos─Campus Lagoa do Sino, 18290-000 Buri, Brazil. , (Brazil)
  • 5 Department d'Hortofruticultura, Botànica i Jardineria, Agrotecnio, Universitat de Lleida, 25198 Lleida, Spain. , (Spain)
Published Article
Journal of Agricultural and Food Chemistry
American Chemical Society
Publication Date
Dec 01, 2021
DOI: 10.1021/acs.jafc.1c04279
PMID: 34852464


The repeated use of herbicides can lead to the selection of multiple resistance weeds. Some populations of Conyza bonariensis occurring in olive groves from southern Spain have developed resistance to various herbicides. This study determined the resistance levels to 2,4-D, glyphosate, diflufenican, paraquat, and tribenuron-methyl in a putative resistant (R) C. bonariensis population, and the possible non-target-site resistance (NTSR) mechanisms involved were characterized. Resistance factors varied as follows: glyphosate (8.9), 2,4-D (4.8), diflufenican (5.0), tribenuron-methyl (19.6), and paraquat (85.5). Absorption of 14C-glyphosate was up to 25% higher in the susceptible (S) population compared to the R one, but 14C-paraquat absorption was similar (up to 70%) in both populations. S plants translocated more than 60% of both 14C-glyphosate and 14C-paraquat toward shoots and roots, while R plants translocated less than 10%. The R population was able to metabolize 57% of the 2,4-D into nontoxic metabolites and 68% of the tribenuron-methyl into metsulfuron-methyl (10%), metsulfuron-methyl-hydroxylate (18%), and conjugate-metsulfuron-methyl (40%). Among the NTSR mechanisms investigated, absorption and translocation could be involved in glyphosate resistance, but only translocation for paraquat. Proofs of the presence of enhanced metabolism as a resistance mechanism were found for tribenuron-methyl and 2,4-D, but not for diflufenican. This research informs the first occurrence of multiple resistance to five herbicide classes (acetolactate synthase inhibitors, 5-enolpyruvylshikimate-3-phosphate synthase inhibitors, photosystem I electron diverters, photosystem II inhibitors, and synthetic auxin herbicides) in C. bonariensis.

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