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25 March 2022 | Story Leonie Bolleurs | Photo Charl Devenish
Prof Liezel Herselman Inuagural Lecture
At the inaugural lecture were from the left: Prof Danie Vermeulen, Dean of the Faculty of Natural and Agricultural Sciences, Prof Liezel Herselman, Dr Adré Minnaar-Ontong, Senior Lecturer in the Department of Plant Sciences and Subject Head of Plant Breeding, and Dr Molapo Qhobela, Vice-Rector: Institutional Change, Strategic Partnerships and Societal Impact.

Prof Liezel Herselman, Academic Head of the Department of Plant Sciences at the University of the Free State (UFS),) delivered her inaugural lecture on the Bloemfontein Campus this week (24 March 2022). The theme of the lecture was the ongoing battle against destructive cereal killers. 

With 28 years of extensive experience as a researcher, her work focuses on marker-assisted disease resistance breeding in wheat within a South African context. When she joined the UFS in 2004, Prof Herselman decided to apply her research expertise in marker-assisted breeding to the problems faced by wheat producers in the Free State and Northern Cape. The Free State is one of the major dryland wheat production areas in South Africa, while irrigation wheat is produced along the major rivers in the Northern Cape. 

Protection against fungal diseases

Concentrating specifically on Fusarium head blight (or wheat scab) and three rust diseases – leaf rust, stem rust, and stripe rust – she has done work to provide wheat plants with ‘tools’ to protect themselves against these fungal diseases.

According to Prof Herselman, there are many genes available in different wheat genotypes and related grass species that provide excellent protection against various races of these diseases. “Some of these genes provide protection or resistance from the seedling stage, while others provide resistance at the adult plant stage. We are thus aiming to combine as many of these genes as possible into a single wheat cultivar, without compromising yield and bread-making quality.”

She says the genes are combined by making crosses between resistant and susceptible cultivars or lines. Conventionally, through a time-consuming process, the incorporation of these genes is tested in the greenhouse and field by infecting plants with the disease to see which plants are resistant and which are not.

They can, however, follow the transfer of these genes to newly developed lines by applying molecular markers. Prof Herselman explains: “A molecular marker is a genomic fragment linked to the gene, which we can follow in the offspring we create from the crosses using different DNA techniques in the laboratory. This enables us to select new wheat lines that contain the highest number of resistance genes. The identified best lines are then used in further crosses and/or released as pre-breeding lines to commercial wheat breeding companies.”

Impact on food security

Her research has an impact on society by providing food security to both commercial and small-scale producers, as well as the end users of wheat (people buying bread and other wheat products). As researcher, it is also important for her to send out students to the workplace who can continue with this task in future.

Prof Herselman believes that when cultivars with fungal-disease tolerance or resistance are released and used by producers, it not only reduces the cost of spraying against diseases, but also increases yields by protecting the crop against fungal diseases. “We live in a world where the population is increasing daily, but land available for agriculture is not increasing and some areas are even lost due to urban development. Increasing yield in available production areas will thus have a positive impact on food security,” she says.

Besides contributing to the country’s food security, she takes pleasure in every aspect of her work. Although she misses the hands-on part of the work as academic head of the department and getting her hands dirty, she still enjoys managing the different research projects (from the conceptualisation phase to data analysis and publishing of results). The part she loves the most is to see the growth in her postgraduate students – from the moment they enter the laboratory for the first time until the day they walk out of the laboratory with their degrees. 

“It adds purpose to my life knowing that I have made a difference in a student’s life and equipped him or her with the necessary tools to be successful in the marketplace. Being able to share your knowledge is a gift, but with that gift comes a lot of responsibility as well. I am, however, up for the challenge,” concludes Prof Herselman. 

News Archive

Research on cactus pear grabs attention of food, cosmetic and medical industry
2015-02-18

Cactus pear
Photo: Charl Devenish

The dedicated research and development programme at the UFS on spineless cactus pear (Opuntia ficus-indica) – also known as prickly pear – has grown steadily in both vision and dimension during the past 15 years. Formal cactus pear research at the UFS started with the formation of the Prickly Pear Working Group (PPWG) in June 2002. It has since gone from strength to strength with several MSc dissertations and a PhD thesis as well as popular and scientific publications flowing from this initiative.

According to Prof Wijnand Swart from the Department of Plant Sciences, the UFS is today recognised as a leading institution in the world conducting multi-disciplinary research on spineless cactus pear.

Cactus pear for animal feed

Increasing demands on already scarce water resources in South Africa require alternative sources of animal feed – specifically crops that are more efficient users of water. One alternative with the potential for widespread production is spineless cactus pear. It is 1.14 x more efficient in its use of water than Old man saltbush, 2.8 x more efficient than wheat, 3.75 x more efficient than lucerne and 7.5 x more efficient than rangeland vegetation.

“Studies on the use of sun-dried cactus pear cladodes suggest that it has the potential to provide some 25% of the basic feed resources required by South Africa’s commercial ruminant feed manufacturing sector,” says Prof HO de Waal of the Department of Animal, Wildlife and Grassland Sciences at the UFS.

Until recently, research has focused extensively on the use of cactus pear as drought fodder. However, this is now beginning to shift, with growing interest in the intensive production of spineless cactus pear for other types of animal feed. One example is the spineless cactus pear fruit, produced seasonal, yielding large quantities of fruit in a relatively short period of a few months in summer. Unless kept in cold storage, the fruit cannot be stored for a long period. Therefore, a procedure was developed to combine large volumes of mashed cactus pear fruit with dry hay and straw and preserve it for longer periods as high moisture livestock feed, kuilmoes – a high water content livestock feed similar to silage.

Cactus pear and Pineapple juice
Photo: Charl Devenish

Cactus pear for human consumption

“In addition to its use as a livestock feed, cactus pear is increasingly being cultivated for human consumption. Although the plant can be consumed fresh as a juice or vegetable, significant value can be added through processing. This potential is considerable: the plant can be pickled; preserved as a jam or marmalade; or dried and milled to produce baking flour. It can also serve as a replacement of egg and fat in mayonnaise,” said Dr Maryna de Wit from the Department of Microbial, Biochemical and Food Biotechnology.

The extraction of mucilage from fresh cladodes can form a gelling, emulsifier, and fat-replacing agent commonly found in food products such as mayonnaise and candy. During an information session to the media Dr De Wit and her team conducted a food demonstration to showcase the use of the cladodes in a juice, chicken stir-fry, biscuits and a salad.

The extrusion of cactus pear seed oil provides a further lucrative niche product to the array of uses. These include high-value organic oil for the cosmetic sector, such as soap, hair gel and sun screens.

The cladodes and the fruit also have medicinal uses. It has anti-viral, anti-inflammatory, pain killing and anti-diabetic agents. It is also high in fibre and can lower cholesterol. The fruit also prevents proliferation of cells and suppresses tumour growth and can even help to reduce a hangover.

In South Africa the outdated perception of cactus pears as thorny, alien invaders, is rapidly disappearing. Instead, farmers now recognise that cactus pear can play a vital role as a high yielding, water-efficient, multi-use crop, said Prof de Waal and the members of the Cactus Pear Team.

Facebook photo gallery
Dagbreek interview with Dr Maryna de Wit  

Research on cactus pear (read the full story)

For more information or enquiries contact news@ufs.ac.za

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