Safeguarding one of the world’s most vital staple foods was at the heart of the inaugural lecture delivered by Prof Botma Visser, Professor in the Department of Plant Sciences at the University of the Free State (UFS), on Wednesday 3 September 2025. Prof Visser shared insights from nearly two decades of research into wheat rust – a devastating crop disease that threatens both South Africa’s harvests and global food security.
“Wheat production in South Africa is threatened by three fungal pathogens that cause rust disease on the crop. Understanding the factors that contribute to virulence on locally grown cultivars is crucial to ensure continued wheat production,” said Prof Visser.
The fight against evolving wheat rusts
For the past 17 years, Prof Visser’s research has focused on the genetic structure of rust populations and the risks they pose to food security. His work has shown that these populations are dynamic and constantly changing due to genetic mutations within existing races, as well as the introduction of new races into South Africa.
“Computer modelling showed that rust can spread over vast distances by prevailing winds. During the 20th Century, at least four Southern African stem rust races managed to move across the Indian Ocean from Southern Africa to Australia. South Africa, in turn, received multiple new races from mid-Africa across Zambia and Zimbabwe, without any means of stopping these introductions,” he explained.
To respond to this challenge, his team recently implemented MARPLE (Mobile And Real-time Plant disEase) diagnostics using fourth-generation nanopore sequencing technology. This approach allows the rapid characterisation of fungal isolates, specifically targeting genes linked to fungicide resistance and virulence.
“This work,” Prof Visser noted, “is part of an effort to safeguard global wheat production.”
His research is a collaborative effort with Prof Willem Boshoff (Department of Plant Sciences, UFS) and Dr Tarekegn Terefe (Agricultural Research Council – Small Grain, Bethlehem). Together, their work has positioned the UFS as an internationally recognised centre of excellence in wheat rust research.
About Prof Botma Visser
Prof Botma Visser obtained his BSc in Botany and Microbiology (1988), BSc Honours in Microbiology (1989), and MSc in Botany (1993) at the University of the Free State, where he also completed his PhD in Botany in 2004.
His career spans more than 18 years of research into wheat rust pathogens, combining annual surveys, race pathotyping, molecular genetics, and cutting-edge sequencing technologies. His expertise has not only advanced understanding of rust population dynamics in South Africa but also contributed to global collaborative studies on crop disease.