Page 65 - University of Pretoria RESEARCH REVIEW 2018
P. 65

The influence of farming practices
on genetic diversity of fungal pathogens
Dave Berger, Department of Plant and Soil Sciences, and FABI
Capital intensive maize farming is the backbone of food security in South Africa, accounting for more than 95% of production. There are, however, an estimated 2,5 million small-holder maize farmers. Understanding the constraints they experience is important for household food security.
Professor Dave Berger and
the Molecular Plant-Microbe Interactions Group have addressed the issue of how different farming practices influence the genetic diversity of fungal pathogens of maize. Their research has focused on the fungus Cercospora zeina that causes the economically important grey leaf spot disease of maize.
In August 2018, the UP team presented a workshop on maize foliar fungal pathogens and molecular diagnostics at Maseno University, Kenya. This was part of a joint South Africa-Kenya collaboration funded
by the respective National Research Foundation of each country. As
part of this bi-lateral collaboration, MSc student Dennis Omondi has spent two sessions of laboratory training at UP. Being involved in a bi-lateral project with Kenya has been particularly gratifying for Prof Berger, who was born and grew up in Kenya.
In the South African study, the KwaZulu-Natal province, a hotspot
for the disease with commercial and small-holder farms in close proximity, was selected. Several hundred isolates of the fungus were collected from each farming system, and population genetic analysis showed that a
David Nsibo, Dennis Omondi and Irene Barnes doing field work in Kenya.
 significant amount of variation was conferred by farming systems. Most importantly, the results indicate that although the fungus can disperse across the province by wind-blown spores, there is selection for greater diversity in small-holder plots.
The project was carried out by PhD student, David Livingstone Nsibo, recipient of a scholarship from the Intra-ACP Mobility Project for Crop Scientists for Africa Agriculture, funded by the European Union. Mentored by Prof Berger and Dr Irene Barnes, David Nsibo’s PhD studies
have also covered the population genetics of C. zeina in small-holder farms of his home country Uganda, as well as in Kenya, Zambia and Zimbabwe. His findings have challenged the hypothesis that the pathogen spread through Africa after an initial introduction to South Africa, and favour alternative hypotheses
of multiple introductions, or even an African origin for C. zeina. Based on the findings, a paper co-authored with Irene Barnes, Ncobile Kunene and Dave Berger was published in the journal Fungal Genetics and Biology in January 2019.
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