Resistance Mechanisms to 2,4-D in Six Different Dicotyledonous Weeds Around the World

Candelario Palma-Bautista,Ignacio Dellaferrera,Mario R Vigna,Joel Torra,Antonia M Rojano-Delgado,Jesús M Rosario,Rafael De Prado

doi:10.3390/agronomy10040566

Abstract

2,4-D resistance is increasing around the world due to both transgenic crops and resistance to other herbicides. The objective of the this study was to characterize the currently unknown mechanisms of 2,4-D resistance in five weed species from around the globe: Amaranthus hybridus (Argentina), Conyza canadensis (Hungary), Conyza sumatrensis (France), Hirschfeldia incana (Argentina) and Parthenium hysterophorus (Dominican Republic), using Papaver rhoeas (Spain) as a standard resistant (R) species. Dose-response trials using malathion and absorption, translocation and metabolism experiments were performed to unravel the resistance mechanisms. R plants produced at least 3-folds less ethylene than susceptible plants, confirming the resistance to 2,4-D, together with resistance factors >4. A. hybridus, P. hysterophorus and P. rhoeas showed both reduced translocation and enhanced metabolism. In the two Conyza sps., the only resistance mechanism found was enhanced metabolism. Malathion synergized with 2,4-D in all these species, indicating the role of cytochrome P450 in the herbicide degradation. In H. incana, reduced translocation was the only contributing mechanism to resistance. Among the six dicotyledonous weed species investigated, there was a differential contribution to 2,4-D resistance of enhanced metabolism and reduced translocation. Thus, extrapolating 2,4-D resistance mechanisms from one weed species to another is very risky, if even related.

Highlights

Released in 1946, 2,4-D was used principally to control a wide spectrum of dicotyledonous weeds [1]
When comparing the S populations across the species, there were no differences in the production of ethylene in S plants of A. hybridus, C. canadensis, C. sumatrensis, P. hysterophorus and
These results suggested a clear 2,4-D resistance in the studied species, except in the case of C. sumatrensis in which a slow evolution of the resistance to 2,4-D was observed, because R plants did not survive the field dose and showed the lowest reduction in ethylene production (3-folds) compared to the rest of the species

Summary

Introduction

Released in 1946, 2,4-D was used principally to control a wide spectrum of dicotyledonous weeds [1]. Agronomy 2020, 10, 566 a phenoxy-carboxylate among the five chemical families within SAH. It is available in several different formulations of the ester, amine salt and acid. SAH action is given by three ways: 1, altering the plasticity of the cell walls; 2, influencing the amount of protein production; and 3, increasing ethylene production [5]. All these effects can cause the plant death.

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Methods

Results

Discussion

Conclusion