School of Molecular Sciences

Postgraduate research profiles

Harmony Clayton

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Thesis

Identification of key steps in the molecular evolution of C4 photosynthesis in Neurachne, a genus of Australian native grasses

Summary

Photosynthesis is the process by which plants use the energy from light to convert carbon dioxide and water into oxygen and energy-rich sugars for growth. C3 photosynthesis is the most common photosynthetic pathway found in plants; however, some plants have evolved a modified version of the pathway, known as C4 photosynthesis, which improves photosynthetic efficiency in challenging environments. Remarkably, C4 photosynthesis has evolved from the ancestral C3 pathway at least 60 times during Earth’s history in a wide range of plants. Each origin is distinct, but the end results are biochemically very similar. What remain poorly understood are the precise molecular changes that occurred during the evolution of the C4 pathway. To answer this I am studying the origins of C4 photosynthesis in Neurachne, a genus of Australian native grasses – and the only grass group known – that contains species using different photosynthetic pathways. My investigations involve characterising and comparing the genes encoding enzymes with central roles in photosynthesis from Neurachne annularis (C3), N. munroi (C4) and N. minor (C3-C4 intermediate), which represent three stages in the evolution of C4 photosynthesis in this genus. My aim is to identify key molecular changes that led to the evolution of C4 photosynthesis in this grass group.

Why my research is important

Facing a global population boom, increased energy demands, and a changing climate, one of the main agricultural goals of the 21st century is to develop crop plants that can produce higher yields, using less water and less fertiliser. Engineering C4 photosynthesis into staple C3 crops like rice and wheat could meet this challenge, but current bioengineering efforts are hampered by a lack of knowledge about the molecular events that led to the evolution of the C4 pathway. Understanding how C4 photosynthesis evolved in grasses will help direct the molecular engineering of C4 crops.