Samuel Caygill
Understanding how glyphosate kills plants
Glyphosate targets the enzyme EPSPS; a key enzyme in the biosynthesis of the aromatic amino acids. However, it is not fully understood how inhibition of EPSPS by glyphosate actually kills the plant. I use a variety of methods, including targeted and non-targeted LC/MS-MS to determine what factors may lead to plant death following glyphosate treatment. Understanding glyphosate lethality is key for predicting resistance mechanisms and discovering ways to reduce the non-target toxicity of glyphosate.
Understanding enolpyruvyl transferase enzymes in plants
There are two enolpyruvyl transferase enzymes. 1. EPSPS, the target of the herbicide glyphosate. 2. MurA, the target of the antibiotic fosfomycin. Some plants encode both enzymes, some encode only EPSPS. I have discovered those plants with both are more tolerant to glyphosate and am currently working to reveal how the enzymatic properties of MurA could allow it to confer glyphosate tolerance.
Caygill S, Dolan L (2023) ATP binding cassette transporters and uridine diphosphate glycosyltransferases are ancient protein families that evolved roles in herbicide resistance through exaptation. PLoS ONE 18(9): e0287356.
Casey, A., Köcher, T., Caygill, S., Champion, C., Bonnot, C. and Dolan, L., (2023) Transcriptome changes in chlorsulfuron-treated plants are caused by acetolactate synthase inhibition and not induction of a herbicide detoxification system in Marchantia polymorpha. Pesticide Biochemistry and Physiology, 191, p.105370.