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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

Africa's Black Rhino conservation strategy must change

2017-07-10

The black rhino is on the brink of extinction. The study that was
published in the Nature Scientific Reports reveals that the
species has lost an astonishing 69% of its genetic variation.
Photo: iStock

The conservation strategy of the black rhino in Africa needs to change in order to protect the species from extinction, a group of international researchers has found. The study that was published in the Nature Scientific Reports reveals that the species has lost an astonishing 69% of its genetic variation.

South African researchers took part
The researchers, which included local researchers from the National Zoological Gardens of South Africa (NZG), have highlighted the fact that this means the black rhino is on the brink of extinction. "We have found that there is a decline in genetic diversity, with 44 of 64 genetic lineages no longer existing," said Prof Antoinette Kotze, the Manager of Research and Scientific Services at the Zoo in Pretoria. She is also affiliate Professor in the Department of Genetics at the University of the Free State and has been involved in rhino research in South Africa since the early 2000s.

DNA from museums and the wild
The study compared DNA from specimens in museums around the world, which originated in the different regions of Africa, to the DNA of live wild animals. The DNA was extracted from the skin of museum specimen and from tissue and faecal samples from animals in the wild. The research used the mitochondrial genome.

"The rhino poaching ‘pandemic’
needs to be defeated, because
it puts further strain on the genetic
diversity of the black rhino.”

Ability to adapt
Dr Desire Dalton, one of the collaborators in the paper and a senior researcher at the NZG, said the loss of genetic diversity may compromise the rhinos’ ability to adapt to climate change. The study further underlined that two distinct populations now exists on either side of the Zambezi River. Dr Dalton said these definite populations need to be managed separately in order to conserve their genetic diversity. The study found that although the data suggests that the future is bleak for the black rhinoceros, the researchers did identify populations of priority for conservation, which might offer a better chance of preventing the species from total extinction. However, it stressed that the rhino poaching ‘pandemic’ needs to be defeated, because it puts further strain on the genetic diversity of the black rhino.

Extinct in many African countries
The research report further said that black rhino had been hunted and poached to extinction in many parts of Africa, such as Nigeria, Chad, Cameroon, Sudan, and Ethiopia. These rhino are now only found in five African countries. They are Tanzania, Zimbabwe, Kenya, Namibia, and South Africa, where the majority of the animals can be found.

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