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08 October 2020 | Story Leonie Bolleurs | Photo Supplied
Dr Cornel Bender
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

Breeding of unique game requires a balance between conservation and sustainable use
2014-05-20

 

Game bred for qualities such as unconventional hair colour or horn quality, may on the long term have unexpected consequences for biodiversity and game farming.

This is according to the inaugural lecture of Prof Paul Grobler from the Department of Genetics at the University of the Free State (UFS).

Prof Grobler feels that the consequences of selective breeding should be examined carefully, as there is currently much speculation on the subject without sound scientific information to back it.

“At the moment, colour variation invokes much interest among game farmers and breeders. Unusual colour variants are already available in different game species. These unusual animals usually fetch much higher prices at auctions compared to prices for the ‘normal’ individuals of the species.”

Examples of these unusual variants are springbuck being bred in white, black or copper colours, the black-backed or ‘saddleback’ impala, and the gold-coloured and royal wildebeest.

A black-backed impala was recently sold for R5,7 million.

“Based on genetic theory, good reason exists why these practices need to be monitored, but one should also take care not to make the assumption that selective breeding will inevitably lead to problems,” warns Prof Grobler.

Grobler says that negative characteristics in a species can sometimes unwittingly be expressed during the selection process for a unique colour. “It is seen, for example, in purebred dogs where the breeding of a new race sometimes brings underlying genetic deviations in the species to the front.” He also believes that some of these animals may not be able to adapt to changing environmental conditions.

“However, one should also look at the positive side: because of the good demand for game, including unusual variants, there is much more game in South Africa today than in many decades. Balance should be found between the aims of conservation and the sustainable utilisation of game.”

Research at the UFS’s Department of Genetics is now trying to establish the genetic effects of intensive game breeding and predict the impact on biodiversity.

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