| Autor: |
Gherekhloo J; Department of Agronomy, Gorgan University of Agricultural Sciences and Natural Resources, 49189-43464, Gorgan, Iran., Fernández-Moreno PT; Department of Agricultural Chemistry and Edaphology, Campus of Rabanales, University of Cordoba, 14071, Cordoba, Spain., Alcántara-de la Cruz R; Departamento de Entomologia/BIOAGRO, Universidade Federal de Viçosa, 36570-900, Viçosa, Brazil. ricardo.la@ufv.br., Sánchez-González E; Department of Agricultural Parasitology, Chapingo Autonomous University, 56230, Texcoco, Mexico., Cruz-Hipolito HE; Bayer CropScience Mexico, 11520, Mexico City, Mexico., Domínguez-Valenzuela JA; Department of Agricultural Parasitology, Chapingo Autonomous University, 56230, Texcoco, Mexico. jose_dv001@yahoo.com.mx., De Prado R; Department of Agricultural Chemistry and Edaphology, Campus of Rabanales, University of Cordoba, 14071, Cordoba, Spain. |
| Abstrakt: |
Glyphosate has been used for more than 15 years for weed management in citrus groves in the Gulf of Mexico, at up to 3-4 applications per year. Goosegrass (Eleusine indica (L.) Gaertn.) control has sometimes failed. In this research, the mechanisms governing three goosegrass biotypes (Ein-Or from an orange grove, and Ein-Pl1 and Ein-Pl2 from Persian lime groves) with suspected resistance to glyphosate were characterized and compared to a susceptible biotype (Ein-S). Dose-response and shikimate accumulation assays confirmed resistance of the resistant (R) biotypes. There were no differences in glyphosate absorption, but the R biotypes retained up to 62-78% of the herbicide in the treated leaf at 96 h after treatment (HAT), in comparison to the Ein-S biotype (36%). The 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity in the Ein-Or and Ein-S biotypes was over 100-fold lower than the Ein-Pl1 and Ein-Pl2 ones. The latter showed a high EPSPS-basal activity, a mutation at Pro-106-Ser position in the EPSPS gene, and EPSPS overexpression. The EPSPS basal and EPSPS overexpression were positively correlated. The R goosegrass biotypes displayed poor glyphosate translocation. Furthermore, this grassweed showed, for the first time, two mechanisms at the target-site level (Pro-106-Ser mutation + EPSPS overexpression) acting together simultaneously against glyphosate. |
