Molecular Mechanisms of Herbicide Resistance

Abstract

Resistance to herbicides occurs in weeds as the result of evolutionary adaptation (Jasieniuk et al. 1996). Basically, two types of mechanisms are involved in resistance (Beckie and Tardif 2012; Délye 2013). Target-site resistance (TSR) is caused by changes in the tridimensional structure of the herbicide target protein that decrease herbicide binding, or by increased activity (e.g., due to increased expression or increased intrinsic activity) of the target protein. Nontarget-site resistance (NTSR) is endowed by any mechanism not belonging to TSR, e.g., reduction in herbicide uptake or translocation in the plant, or enhanced herbicide detoxification (reviewed in Délye 2013; Yuan et al. 2007).

EPSPS Gene Amplification is Present in the Majority of Glyphosate-Resistant Illinois Waterhemp (Amaranthus tuberculatus) Populations

“…Alternative Target-Site Resistance. Some resistant plants were further analyzed for the EPSPS Pro106Ser point mutation (Bell et al 2013;Nandula et al 2013) using a derived cleaved amplified polymorphic sequences (dCAPS) assay designed according to procedures described by Délye et al (2014). A fragment containing codon 106 was amplified using the forward primer EPSf1 (5 0 -ATG TTG GAC GCT CTC AGA ACT CTT GGT-3 0 ) originally designed for qPCR (Gaines et al 2010) and reverse primer eps106wt-R3 (5 0 -CTC CAG CAA CGG CAA CCG CAA CTG TCC ATG-3 0 ).…”

Involvement of Epigenetic Mechanisms in Herbicide Resistance: The Case of Conyza canadensis

“…Consequently, in the presence of either regulatory mutations or epigenetic regulations, the investigation and detection of herbicide resistance is mostly achieved by analyzing significant differences in the expression of genes between resistant and sensitive populations [22].…”

“…Consequently, efficient weed management becomes even more challenging and should utilize additional methods in order to control glyphosate-resistant weeds [18,19]. Several 'omics' approaches could help elucidating the genetic bases of complex resistances, e.g., transcriptomes are already available for several broadleaved weed species [20][21][22].…”

“…On the other hand, mutations are changes in a DNA sequence that can influence either TSR, causing an increase in the expression of the herbicide target protein that compensates for the herbicide inhibitory action, or NTSR by creating a variation in the expression of herbicide-metabolizing enzyme(s) or of transporter proteins that will lead to an increase in herbicide degradation or translocation, respectively [22]. Epigenetic processes (e.g., DNA methylation or histone modifications) can also be involved in the regulation of gene expression [23,24].…”

Protocol for the evaluation of data concerning the necessity of the application of herbicide active substances to control a serious danger to plant health which cannot be contained by other available means, including non-chemical methods

“…Herbicide resistance can also be defined at the plant population level and then refers to the situation where the frequency of herbicide resistant mutants is such that herbicide application in the standard dose does not provide adequate weed control anymore. Different types of mechanisms are involved in herbicide resistance (Délye et al, 2015) and confer different agronomic situations. Once a weed field population contains a too high fraction of herbicide resistant individuals, it is very difficult to reverse this situation.…”