Two former classmates from Bulawayo, Zimbabwe, recently received their PhDs in agricultural sciences from Stellenbosch University. Here’s the newly capped doctors’ story.
Providence Moyo and Mukani Moyo were among a group of 18 PhD and 61 master’s students who recently graduated from Stellenbosch University’s Faculty of AgriSciences. The PhD students came from six African countries, namely South Africa, Ghana, Nigeria, Namibia, Zimbabwe and Mozambique.
“We’re about the same age, have the same surname and met back in 2002 while studying biological sciences at Zimbabwe’s Midlands State University,” Providence says. After earning their undergraduate degrees the two friends went their separate ways, only to meet up again in Stellenbosch a few years later to pursue their postgraduate studies. They both researched diseases associated with grapevines. Providence received a PhD in plant pathology and Mukani a PhD in wine biotechnology.
“One of Stellenbosch University’s missions is to extend its footprint in Africa, especially its research footprint,” says Professor Danie Brink, acting dean of the Faculty of AgriSciences. “One way is by providing postgraduate support to students from around the continent. This is reflected in the growing numbers of postgraduate students from African countries in the Faculty of AgriSciences.”
Love at first blight
With her love of plant pathology, Providence focused her research on Diatrypaceae fungi species. She surveyed which types of Diatrypaceae fungi species are found on grapevines and other woody plants growing near South African vineyards. She found 15 species of Diatrypaceae and established that some species are associated with specific dieback symptoms. In the process she identified a new species of Eutypa that has never been described before and seven species of Diatrypaceae that viticulturists and plant pathologists never knew occurred in South Africa.
The project was initiated after local plant pathologists received reports from overseas about the discovery of new fungal species which were thought to also be involved in the development Eutypa dieback. “We didn’t know whether these species occurred in South Africa and therefore decided to investigate,” says Providence, who now works as a plant pathologist at Citrus Research International in Mbombela (formerly Nelspruit).
Providence completed her research under the supervision of Dr Francois Halleen of the Agricultural Research Council and Dr Lizél Mostert of Stellenbosch University’s department of plant pathology. Her study is more than just a check list of the types of fungi that cause dieback in South African vineyards. She’s one of several scientists who developed a laboratory test that plant pathologists and viticulturists can use to detect whether the species Eutypa lata and Cryptovalsa ampelina are present in the woody part of a vine.
Right up her alley
For her PhD in wine biotechnology, Mukani used various molecular techniques to investigate the interplay between grapevines and fungal pathogens that causes diseases. In particular, she investigated what happens when grapevine plants are infected with Botrytis cinerea, a fungal pathogen that causes grey mould on grapevines.
She used techniques that made it possible to identify the fungus’ attack strategies and plants’ defence strategies. These so-called interactome studies lead to interesting insights into the interaction between grapevines and their pathogens.
Mukani found proof that some of grapevines’ defences are not used, or even effective against the pathogen. For example, a grapevine defence protein, the polygalacturonase-inhibiting protein (PGIP), was shown to be ineffective against protecting the plants against Botrytis, while the same protein when tested in tobacco helps to effectively control the fungus.
“Vines are naturally susceptible to Botrytis infections and unlike other plant species, the PGIP protein does not seem to play a defence role in protecting the grapevine against such infection,” she explains.
The best part of her PhD – and probably also the part that taught her many a lesson in tenacity – has been to find out why the gene provides protection in some plants, but not in others, Mukani says. “It has to do with changes in the cell walls of plants overexpressing the grapevine PGIP gene, emission of volatile organic compounds and expression profiles of genes involved in crucial defence mechanisms such as hormonal regulation. Studying the process both from the perspective of the pathogen and the plant made understanding the details possible in the end.”
Mukani completed her degree under the supervision of Professor Melané Vivier of the Institute for Wine Biotechnology, which is part of the department of viticulture and oenology at Stellenbosch University.