Interest in biofortification leads to pro-Vitamin A maize first for SA
Dr Aleck Kondwakwenda was on track to become a soil scientist, when he became fascinated by the idea that the nutrient content of crops could be boosted through plant breeding.
Kondwakwenda, who graduated recently with a PhD in plant breeding, studied for a master’s degree in soil science at Ghent University in Belgium. After that he was awarded a scholarship to do a PhD in soil science at UKZN, but his heart wasn’t in it.
“When I got here, it was very difficult for me to concentrate and even write the proposal, because I had no interest in soil science. My interest was in plant breeding,” he recalls.
When he met Dr Julia Sibiya, who heads the Improved Masters in Cultivar development for Africa (IMCDA) programme, and found out about the courses in plant breeding being taught by IMCDA and the African Centre for Crop Improvement (ACCI), he made the switch.
“I decided to use those theory classes to bridge my soil science background to plant breeding,” he says. His PhD was supported by The World Academy of Sciences (TWAS), National Research Foundation and Alliance for a Green Revolution in Africa (AGRA). It investigated breeding provitamin A maize — ie maize with enhanced Vitamin A — for southern Africa, that is also drought tolerant and high yielding. He was supervised by Sibiya and Dr Rebecca Zengeni.
“I chose the topic because it interested me,” he says. “My interest was in biofortification, in the idea that through breeding you can change the nutrient status of a crop.
“I wondered how plant breeders did it. I chose to focus on maize because it’s a staple food eaten by the majority of people, especially in Southern Africa.”
Vitamin A deficiency affects more than 40% of children under five in sub-Saharan Africa. It can cause a range of conditions, including blindness in adults and children and even death in small children, because it compromises their immune systems.
Biofortification of this crop makes sense because one of the main reasons for Vitamin A deficiency is the limited diet of many Africans, who rely on white maize for nutrition.
Adding drought tolerance to the mix is also a no-brainer. The number of provitamin A maize varieties that have been developed in South Africa is small and none of them has been primarily bred for drought tolerance.
“I added drought tolerance because it’s one of the major stresses affecting agriculture, especially for poorly resourced farmers who cannot afford irrigation,” says Kondwakwenda. “This is a way of tackling two issues, drought and Vitamin A deficiency among those who can’t afford a balanced diet.”
His soil science background came in useful, especially because of the drought tolerance aspect. “Soil water status and drought occurrence are correlated issues,” he explains.
He began his research by looking for genetic diversity in 46 tropical yellow maize inbred lines, obtained from CIMMYT in Zimbabwe and IITA in Nigeria. The yellow hue is caused by a higher level of beta-Carotene, a Vitamin A precursor.
Promising candidates were identified through genetic evaluation and screening of inbred lines in greenhouses and in the field.
“We measured the amount of proline, an amino found in plants that increases under drought conditions, and other traits to select for drought-tolerance. We also screened for high beta-Carotene.”
After crossing the best parents, 64 experimental hybrids were produced that were later evaluated under drought conditions in the field in KwaZulu-Natal at Jozini, Ukulinga and Cedara, as well as in Zimbabwe.
As a result of his research, Kondwakwenda produced 12 inbred lines that can be used by other breeders as parents in their hybridisation programmes, as well as five experimental hybrids that are drought tolerant and have higher levels of beta-Carotene.
The importance of his work was recognised last year in Belgium by an invitation to give an oral presentation at the annual Tropentag conference, organised by a consortium of European universities. He has also had an article published in the journal Maydica and has other articles under review by different journals.
Looking ahead, Kondwakwenda says further testing must be done of the varieties he’s developed and then they can be released by the UKZN breeding programme or other public or private maize breeding programmes.
He’s currently applying for post-doctoral funding for the final stage of testing.