Resistance Mechanisms ofSaccharomyces cerevisiaeto Commercial Formulations of Glyphosate Involve DNA Damage Repair, the Cell Cycle, and the Cell Wall Structure

Abstract

The use of glyphosate-based herbicides is widespread and despite their extensive use, their effects are yet to be deciphered completely. The additives in commercial formulations of glyphosate, though labeled inert when used individually, have adverse effects when used in combination with other additives along with the active ingredient. As a species, Saccharomyces cerevisiae has a wide range of resistance to glyphosate-based herbicides. To investigate the underlying genetic differences between sensitive and resistant strains, global changes in gene expression were measured, when yeast were exposed to a glyphosate-based herbicide (GBH). Expression of genes involved in numerous pathways crucial to the cell’s functioning, such as DNA replication, MAPK signaling, meiosis, and cell wall synthesis changed. Because so many diverse pathways were affected, these strains were then subjected to in-lab-evolutions (ILE) to select mutations that confer increased resistance. Common fragile sites were found to play a role in adaptation to resistance to long-term exposure of GBHs. Copy number increased in approximately 100 genes associated with cell wall proteins, mitochondria, and sterol transport. Taking ILE and transcriptomic data into account it is evident that GBHs affect multiple biological processes in the cell. One such component is the cell wall structure which acts as a protective barrier in alleviating the stress caused by exposure to inert additives in GBHs. Sed1, a GPI-cell wall protein, plays an important role in tolerance of a GBH. Hence, a detailed study of the changes occurring at the genome and transcriptome levels is essential to better understand the effects of an environmental stressor such as a GBH, on the cell as a whole.

The Yeast Atlas of Appalachia: Species and Phenotypic Diversity of Herbicide Resistance in Wild Yeast

“…However, in the over 300 commercial formulations, glyphosate is not the only ingredient. Additives improve the action of glyphosate and have effects on cellular metabolism on their own [27,28]. By changing the growth media, the effect of the additives can be separated.…”

“…Between genetically diverse yeasts, there are tens of thousands of SNPs [29]. Quantitative trait loci analysis of glyphosate resistance shows that it is a polygenetic trait [26][27][28] and there are multiple changes that can occur to select for glyphosate resistance [27,28]. Through QTL and in-lab-evolution studies, the additives in glyphosate based herbicides (GBH) affect diverse pathways such as cell wall and mitochondria [27].…”

“…Quantitative trait loci analysis of glyphosate resistance shows that it is a polygenetic trait [26][27][28] and there are multiple changes that can occur to select for glyphosate resistance [27,28]. Through QTL and in-lab-evolution studies, the additives in glyphosate based herbicides (GBH) affect diverse pathways such as cell wall and mitochondria [27]. Commercial preparations also contain detergents as additives that have additional effects such as cell wall stress and cell cycle arrest [27].…”

“…Through QTL and in-lab-evolution studies, the additives in glyphosate based herbicides (GBH) affect diverse pathways such as cell wall and mitochondria [27]. Commercial preparations also contain detergents as additives that have additional effects such as cell wall stress and cell cycle arrest [27]. Rich media, such as YPD, is an undefined media that contains all amino acids, fatty acids, and other biomolecules.…”

“…Rich media, such as YPD, is an undefined media that contains all amino acids, fatty acids, and other biomolecules. S. cerevisiae that are sensitive to the commercial preparations in rich media are due to the detergents rather than from glyphosate [27].…”