Occurrence and importance of herbicide resistance caused by degradation enhancement for weed management

Abstract

Non-target-site resistance (NTSR) to herbicides mainly caused by enhanced degradation is highly problematic due to the occurrence of biotypes with multiple resistance and is a new challenge for weed management and herbicide use. Recently, enzymes associated with xenobiotic degradation especially cytochrome P450, GSTs and ABC transporters have been associated with the herbicide resistance in several weeds. This knowledge opens a new window to understand the evolution of NTSR. The aims of this review are to discuss the current knowledge of the gene regulation associated with the herbicide resistance caused by enhanced herbicide degradation and to analyze the main consequences of this problem for the adequate herbicide use and weed management. Multiple herbicide resistance caused by degradation enhancement occurs in Lolium rigidum, Alopecurus myosuroides, Echinochloa phyllopogon and in several other species. The level of herbicide resistance caused by degradation enhancement is affected by environmental factors in several cases, which difficult the resistance diagnostic and facilitate its distribution. The modern weed management should consider the characteristics of the herbicide degradation, since the simple rotation of herbicides mechanism of action might not be enough to prevent the herbicide resistance. The use of synergistic mixtures of herbicides and other enzyme inhibitors may contribute to prevent the evolution and spreading of NTSR weed herbicide resistance.