Arnaud Thierry Djami Tchatchou, PhD

I graduated with a PhD (Molecular Biology, 2012) from the University of the Witwatersrand, South Africa and a MSc ( Biochemistry, 2007) from the University of Yaounde 1, Cameroon. My  expertise is in research regarding plant-pathogen interaction with the focus on plant defense response and pathogen virulence mechanism. Before joining the Kunkel Lab, I worked as a post-doctoral fellow (2012-2016) at the University of Johannesburg, the University of the Witwatersrand (2013-2014) and at the University of South Africa (2016-2017).

I was born in a small village, Ndoungue in Cameroon and raised up by my grandparents who were farmers and hunters. Each time my grandfather brought an animal home for food I was always curious to see what was inside the stomach and the head. As a primary and high school student I was fascinated by biology to learn about natural world and the ways organisms interact with their environment which were more real to me than mathematics, literature, etc. As I was growing up with my grandparents, we used to cultivate the ground manually to sow  cassava, sweet potatoes, maize (see picture) and many vegetable crops. This is how my passion for plants originated.  

Seeing my parents struggle with plant disease in those days, which resulted sometime in severe losses in agricultural yield, I was curious to know why our crops couldn’t defend themselves against those diseases. These struggles and difficulties faced by my parents became the motivation that led me to study and seek to understand how plants defend themselves against pathogen attack. Since then I have always been fascinated  by the field of plant biology to address issues of global importance such as improving agricultural productivity and ensuring sustainable food security. As a graduate student and postdoctoral researcher, I have sought to understand the molecular basis of plant disease resistance using a wide array of approaches, including biochemistry and molecular biology.

Throughout my scientific career I  used various organisms (Colletotrichum gloeosporioides, Colletotrichum sublineolum, Pectobacterium carotovorum andPseudomonas syringae) as well as some defense priming agents (isonitrosoacetophenone, hexanoic acid, azelaic acid and bacterial lipopolysaccharide) to study their interaction with both  model plants (Arabidopsis thaliana and Nicotiana tabacum) and crop species (avocado, sorghum, tomato and  chili pepper). I have  identified and characterized various defense and virulence-related genes to uncover the mechanism of plant disease resistance and virulence.

In Prof Barbara Kunkel’s group at Washington University in St Louis, my research focus is to investigate the roles of the plant hormone auxin (indole acetic acid, IAA) during pathogenesis of Pseudomonas syringae DC3000 on Arabidopsis thaliana. I found that P. syringae uses IAA  in  at  least  two  different  ways  to  promote  virulence  and  disease:  as  a  plant  hormone  to suppress  plant  defenses  and   as  a  microbial  signaling  molecule  to  regulate  virulence  gene expression (the subject of the paper we just published in MPMI).  Currently my research focus is to translate the science discoveries about auxin  that we made using Arabidopsis  to two agriculturally important plants, tomato and cassava using Xanthomonas campestris an economically important pathogen. This study will provide new insights into mechanisms regulating Xanthomonas/host interactions which can be exploited to develop new strategies for protection of tomato and cassava against devastating plant diseases caused by Xanthomonas. During the years I spent here I learned a lot about working with transgenic plants and gained more knowledge in microbiology with excellent mentorship from Professor Kunkel which I think will boost my research career.