First Case of Glyphosate Resistance in Bromus catharticus Vahl.: Examination of Endowing Resistance Mechanisms.

ABSTRACT: Bromus catharticus Vahl. has been used as a valuable forage crop, but it has also been noted as a weed of winter crops and an invader in several countries. In Argentina, a putative glyphosate-resistant population of B. catharticus was identified as a consequence of the lack of effective control with glyphosate in the pre-sowing of wheat. Plant survival and shikimate accumulation analysis demonstrated a lower glyphosate-sensitivity of this population in comparison to a susceptible B. catharticus population. The resistant population was 4-fold more resistant to glyphosate than its susceptible counterpart. There was no evidence of target-site mechanisms of glyphosate resistance or an enhanced capacity to metabolize glyphosate in the resistant population. However, the resistant plants showed a lower foliar retention of glyphosate (138.34 ?l solution g^-1 dry weight vs. 390.79 ?l solution g^-1 dry weight), a reduced absorption of ¹⁴C-glyphosate (54.18 vs. 73.56%) and lower translocation of ¹⁴C-glyphosate from the labeled leaf (27.70 vs. 62.36%). As a result, susceptible plants accumulated a 4.1-fold higher concentration of ¹⁴C-glyphosate in the roots compared to resistant plants. The current work describes the first worldwide case of glyphosate resistance in B. catharticus. A reduced foliar retention of herbicide, a differential rate of glyphosate entry into leaves and an altered glyphosate translocation pattern would be the most likely mechanisms of glyphosate exclusion.

SUBMITTER: Yanniccari M 

PROVIDER: S-EPMC7930564 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature