Matthew Marsden

Understanding the molecular basis of gravitropism and growth angle control

About me

During my time as an undergraduate at the University of Leeds, I really enjoyed lectures focused on plant biology and the molecular pathways that underlie their tropic responses. As such, I decided to write my 3rd year dissertation to assess how current research has shaped our understanding of the molecular and biophysical processes underlying gravitropism. This allowed me to identify several key areas in which our understanding of gravitropism was incomplete. As such, I was keen make my own contribution to the literature and work towards answering some of these outstanding questions.

For my masters project, I therefore worked in the Kepinski lab to assess the curvature dynamics of gravistimulated Arabidopsis roots using a novel imaging system and software, where I discovered that Sachs’ longstanding sine saw seemed to be insufficient to explain the gross gravitropic bending behaviour of a plant organ. I showed that the gravitropic response can be seemingly divided into several phases with differences in the rate at which the bending of the root tip accelerates or decelerates. During this, I learned several skills that will be directly related to my PhD as I seek to further investigate curvature dynamics, in addition to exploring the molecular and biophysical underpinnings of other stages of the gravitropic response.

Overall, this PhD will allow me to nurture my skills in a field that ultimately works to improve food security, as well as equip me with the skills necessary for a career in research.

My research

Gravitropism is a fundamental process in the control of plant architecture and yet despite more than a century of research the mechanisms by which primary roots and shoots maintain vertical growth remain poorly understood. Recent work in the Kepinski and Peckham groups at the University of Leeds have combined molecular and genetic methods and novel plant imaging/computer vision techniques to uncover crucial clues as to the nature of the basic mechanism by which plants can detect their orientation in the gravity field and alter their growth accordingly.

This project will explore and extend these new insights using genetic, biochemical and cell biological approaches, to elucidate how the physical signal of sedimenting amyloplasts within specialised gravity-sensing cells is converted into a biochemical signal that controls the distribution of auxin within plants organs and ultimately their angle of growth with respect to gravity.