Samuel Caygill

Current projects:

A forward genetic screen for uncovering novel mechanisms of herbicide resistance

Weeds are the greatest biotic threat to global crop yields. Herbicides are a component of integrated weed management systems that reduce the impact of weeds on crop yield. However, the long-term use of a few herbicide modes of action has led to the evolution of herbicide resistance in weeds. One part of my project aims to discover genes that, when overexpressed, lead to herbicide resistance.

Improving the kinetic properties of the glyphosate target enzymes used in glyphosate-tolerant crops

Glyphosate is the dominant herbicide worldwide and is a key tool for achieving high yields while minimising the environmental impacts of intense agriculture. The primary reason for its high level of use is the development of and widescale adoption of glyphosate-tolerant crops. However, glyphosate-tolerant crops have lower yields than their glyphosate-sensitive counterparts – likely due to encoding a less kinetically efficient glyphosate target enzyme. I am using a combination of approaches to develop a kinetically superior target that is resistant to glyphosate.

Understanding the mechanisms through which Glyphosate kills plants

Glyphosate targets 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS); a key enzyme in the shikimate pathway. As a result, plants treated with glyphosate have disrupted the biosynthesis of aromatic amino acids. However, it is not fully understood how glyphosate treatment causes plant death. Understanding the cause of death in glyphosate-treated plants may be important for predicting resistance mechanisms and ways to potentially reduce the non-target toxicity of glyphosate.