Molecular cytogenetics to characterize mechanisms of gene duplication in pesticide resistance

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. (c) 2017 Society of Chemical Industry