Molecular cytogenetics to characterize mechanisms of gene duplication in pesticide resistance

Abstract

Recent advances in molecular cytogenetics empower construction of physical maps to illustrate the precise position of genetic loci on the chromosomes. Such maps provide visible information about the position of DNA sequences, including the distribution of repetitive sequences on the chromosomes. This is an important step toward unraveling the genetic mechanisms implicated in chromosomal aberrations (e.g., gene duplication). In response to stress, such as pesticide selection, duplicated genes provide an immediate adaptive advantage to organisms that overcome unfavorable conditions. Although the significance of gene duplication as one of the important events driving genetic diversity has been reported, the precise mechanisms of gene duplication that contribute to pesticide resistance, especially to herbicides, are elusive. With particular reference to pesticide resistance, we discuss the prospects of application of molecular cytogenetic tools to uncover mechanism(s) of gene duplication, and illustrate hypothetical models that predict the evolutionary basis of gene duplication. The cytogenetic basis of duplicated genes, their stability, as well as the magnitude of selection pressure, can determine the dynamics of the genetic locus (loci) conferring pesticide resistance not only at the population level, but also at the individual level. © 2017 Society of Chemical Industry.

The Draft Genome of Kochia scoparia and the Mechanism of Glyphosate Resistance via Transposon-Mediated EPSPS Tandem Gene Duplication

“…With this information in conjunction with previously published cytogenetic work (Jugulam et al. 2014; Jugulam and Gill 2018), we propose a model for the structure of the EPSPS CNV from resistant kochia individuals (fig. 5).…”

Evolution of target and non-target based multiple herbicide resistance in a single Palmer amaranth (Amaranthus palmeri) population from Kansas

“…Husnot] (Salas et al 2012(Salas et al , 2015, and brome grass (Bromus diandrus Roth) (Malone et al 2016). However, the mechanism of amplification of the EPSPS gene appears to be different in different weeds (Jugulam and Gill 2017).…”

Re-registration Challenges of Glyphosate in the European Union

“…As for emerging plant resistance against glyphosate, glyphosate itself and glyphosate-based herbicides have been shown to affect the disease resistance and health of plants by undermining their innate physiological defenses in mechanisms related to the mode of action of glyphosate, even in crops engineered for glyphosate-tolerance, and by interferences with the local microbial ecology in the rhizosphere (Martinez et al, 2018). The evolution of resistance was shown to occur due to gene amplification (Chen et al, 2017;Dolatabadian et al, 2017;Fernandez-Escalada et al, 2017;Han et al, 2017;Jugulam and Gill, 2018). Epigenetic alterations through increased levels of DNA and histone methylation were identified in response to exposure to glyphosate (Nardemir et al, 2015;Kim et al, 2017;Margaritopoulou et al, 2018;Markus et al, 2018).…”