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Plant Sciences graduate contributes technique to manage stem rust

08 October 2020 | Story Leonie Bolleurs | Photo Supplied

Dr Cornel Bender received her PhD qualification at the virtual graduation ceremonies in October. The title of her thesis is: Stem rust resistance in South African wheat and triticale.

The rapid distribution of disease-causing organisms such as Ug99, a wheat stem-rust pathotype, pointed out just how vulnerable global cereal production is to disease outbreaks.

These cereals include wheat, barley, rye, oats, triticale, rice, maize, and millet and are one of the most important food sources for human consumption.

According to Dr Cornel Bender, the projected world population of 10 billion in 2057 requires a growth of more than 40% in cereal production. Wheat is grown on more hectares than any other cereal and is one of the most important sources of calories for humans. However, the growth rate of wheat yields has declined from the 1960s to the 1990s. Therefore, it is essential to increase global wheat production.

“With the regular appearance of more aggressive stem rust pathotypes in South Africa, there is a constant need to discover new sources of resistance, understand the genetic base of presently deployed sources in wheat, triticale and barley cultivars, and to manipulate the deployment of resistant sources through a more sustainable approach,” says Dr Bender.

Her PhD thesis, titled: Stem rust resistance in South African wheat and triticale, includes various fundamental aspects for the effective management of stem rust in South Africa.

Dr Bender is a Professional Officer in the Division of Plant Pathology in the Department of Plant Sciences, who received her PhD at the virtual graduation ceremonies in October.

Innovative and cost effective

Her promotors, Prof Zakkie Pretorius, Research Fellow, and Dr Willem Boshoff, Senior Lecturer in the Department of Plant Sciences, believe that she used an innovative approach to develop a cost-effective phenotyping method to select for more durable resistance types in a controlled greenhouse environment.

“In the past, results obtained from field trials used to assess adult plants for stem-rust resistance, were often influenced by abiotic factors, were seasonable in nature, expensive, and time consuming; therefore, the development of a dependable greenhouse screening system provides an important additional instrument for rust research,” says Dr Bender.

She adds that the greenhouse technique is used worldwide to screen for adult plant resistance and contribute to save time and money.

Broadening our knowledge

“Inheritance studies were undertaken to determine the genetic base of stem-rust resistance in selected South African wheat and triticale cultivars (developed from wheat/rye crosses) through seedling analysis as well as greenhouse and fieldwork,” she says.

Dr Bender believes the use and development of different resistance screening methods, the elucidation of host genetics, as well as the use of histological and microscopic methods to study early resistance responses, broaden our knowledge and understanding of stem-rust resistance in South African wheat and triticale cultivars.

Ultimately, rust researchers, grain producers, and also the general public – through access to their daily bread – will benefit from her study.

News Archive

Nanotechnology breakthrough at UFS

2010-08-19

Ph.D students, Chantel Swart and Ntsoaki Leeuw

Scientists at the University of the Free State (UFS) made an important breakthrough in the use of nanotechnology in medical and biological research. The UFS team’s research has been accepted for publication by the internationally accredited Canadian Journal of Microbiology.

The UFS study dissected yeast cells exposed to over-used cooking oil by peeling microscopically thin layers off the yeast cells through the use of nanotechnology.

The yeast cells were enlarged thousands of times to study what was going on inside the cells, whilst at the same time establishing the chemical elements the cells are composed of. This was done by making microscopically small surgical incisions into the cell walls.

This groundbreaking research opens up a host of new uses for nanotechnology, as it was the first study ever in which biological cells were surgically manipulated and at the same time elemental analysis performed through nanotechnology. According to Prof. Lodewyk Kock, head of the Division Lipid Biotechnology at the UFS, the study has far reaching implications for biological and medical research.

The research was the result of collaboration between the Department of Microbial, Biochemical and Food Biotechnology, the Department of Physics (under the leadership of Prof. Hendrik Swart) and the Centre for Microscopy (under the leadership of Prof.Pieter van Wyk).

Two Ph.D. students, Chantel Swart and Ntsoaki Leeuw, overseen by professors Kock and Van Wyk, managed to successfully prepare yeast that was exposed to over-used cooking oil (used for deep frying of food) for this first ever method of nanotechnological research.

According to Prof. Kock, a single yeast cell is approximately 5 micrometres long. “A micrometre is one millionth of a metre – in laymen’s terms, even less than the diameter of a single hair – and completely invisible to the human eye.”

Through the use of nanotechnology, the chemical composition of the surface of the yeast cells could be established by making a surgical incision into the surface. The cells could be peeled off in layers of approximately three (3) nanometres at a time to establish the effect of the oil on the yeast cell’s composition. A nanometre is one thousandth of a micrometre.

Each cell was enlarged by between 40 000 and 50 000 times. This was done by using the Department of Physics’ PHI700 Scanning Auger Nanoprobe linked to a Scanning Electron Microscope and Argon-etching. Under the guidance of Prof. Swart, Mss. Swart en Leeuw could dissect the surfaces of yeast cells exposed to over-used cooking oil.

The study noted wart like outgrowths - some only a few nanometres in diameter – on the cell surfaces. Research concluded that these outgrowths were caused by the oil. The exposure to the oil also drastically hampered the growth of the yeast cells. (See figure 1)

Researchers worldwide have warned about the over-usage of cooking oil for deep frying of food, as it can be linked to the cause of diseases like cancer. The over-usage of cooking oil in the preparation of food is therefore strictly regulated by laws worldwide.

The UFS-research doesn’t only show that over-used cooking oil is harmful to micro-organisms like yeast, but also suggests how nanotechnology can be used in biological and medical research on, amongst others, cancer cells.

Figure 1. Yeast cells exposed to over-used cooking oil. Wart like protuberances/ outgrowths (WP) is clearly visible on the surfaces of the elongated yeast cells. With the use of nanotechnology, it is possible to peel off the warts – some with a diameter of only a few nanometres – in layers only a few nanometres thick. At the same time, the 3D-structure of the warts as well as its chemical composition can be established.

Media Release
Issued by: Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt@ufs.ac.za
18 August 2010

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