Thickening of the cell wall increases the resistance of S. cerevisiae to commercial formulations of glyphosate

The use of glyphosate-based herbicides is widespread and despite its extensive use, its effects are yet to be deciphered completely. The additives in commercial formulations of glyphosate, though labeled as inert when used individually, have adverse effects when used in combination with other additives and 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 commercial formulation of glyphosate (CFG). Changes in gene expression involved in numerous pathways such as DNA replication, MAPK signaling, meiosis, and cell wall synthesis. 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 mechanisms used by cells to attain resistance with long-term exposure to CFG. The cell wall structure acts as a protective barrier in alleviating the stress caused by exposure to CFG. The thicker the cell wall, the more resistant the cell is against CFG. Hence, a detailed study of the changes occurring at the genome and transcriptome level is essential to better understand the possible effects of CFG on the cell as a whole.\n\nAuthor SummaryWe are exposed to various chemicals in the environment on a daily basis. Some of these chemicals are herbicides that come in direct contact with the food we consume. This makes the thorough investigation of these chemicals crucial. Some of the most commonly used herbicides around the world are glyphosate-based. Their mode of action effects a biosynthetic pathway that is absent in mammals and insects and so it is deemed safe for consumption. However, there are many additives to these herbicides that increase its effects. Thorough testing of these commercially available herbicides is essential to decipher all the potentially adverse effects that it could have on a cell. Saccharomyces cerevisiae has a wide range of genetic diversity, making it is suitable to test different chemicals and identify any harmful effects. In this study, we exposed yeast cells to some glyphosate-based herbicides available in the market, to understand what effects it could have on a cell. We found that the additives in the herbicides have an effect on the cell wall and the mode of entry of glyphosate into the cell.