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Pelly Malebe's research on helping plants withstand
drought is personal as well as scientific. She grew up in South
Africa's drought-prone northern province of Limpopo, where crop
failures are frequent.
If the affected crop is food for family consumption, the
result can be hunger. If it is a crop for trade or export, the loss of
earnings can also mean too little food on the family table, as well as
threatening commercial farmers, both large and small.
As a doctoral student at the University of Pretoria,
Malebe is studying the drought-survival mechanisms of tea plants under
stress – and has identified a DNA marker for those plants more able to
withstand drought. "This can be used to identify suitable
drought-tolerant cultivars to benefit the commercial tea industry," she
says.
In effect, Malebe has found a shortcut that suggests
that a particular tea plant will tolerate drought conditions, without
having to wait to see if and how the plant grows. Happily, the
drought-tolerant plants can adapt to excess moisture, which means they
can survive rainy weather as well.
Malebe's research is supported by RISE, the Regional
Initiative in Science and Education, aimed at building capacity for
science research and teaching in African universities. Funded by the
Carnegie Corporation of New York, a charitable foundation, RISE works
through a series of thematic networks, including Sabina, which stands
for the Southern African Biochemistry and Informatics for Natural
Products Network.
Sabina members include the Tea Research Foundation of
Central Africa and the universities of Malawi, Namibia and Dar es
Salaam [Tanzania], as well as South Africa's universities of the
Witwatersrand and Pretoria. South Africa's Council for Scientific and
Industrial Research also participates.
Biochemistry Professor Zeno Apostolides, founder of the
University of Pretoria's Tea Research Laboratory, is a Sabina faculty
advisor supervising three PhD students, including Malebe and fellow
researcher Nicholas Mphangwe.
Before he was accepted into the Sabina programme,
Mphangwe had been working as a plant breeder for the Tea Research
Foundation in his home country of Malawi, where tea provides about 30
percent of the country's foreign exchange and about five percent of the
world's tea crop.
Since one of Rise's goals is to enhance scientific
skills among scientists in mid-career, Mphangwe was able to take leave
from his job to become part of the Sabina programme. In the lab, he is
probing genetic markers to identify cultivars more adaptable to African
growing conditions and more resistant to drought, insects, diseases and
low temperatures.
"In Malawi, Zimbabwe and Zambia, the main work on tea is
being carried out at research stations, so we tea breeders are still
continuing to go into the field and visually assess promising
cultivars," Mphangwe said. "I hope eventually to develop cultivars with
good off-season growth, so as to extend the growing season."
Once he earns his PhD, Mphangwe plans to return to
Malawi to work with the Tea Research Foundation of Central Africa. This
non-profit organisation is funded by Malawi and Zimbabwe tea growers to
improve technologies. Some of the tea cultivars it has developed are
also grown in Tanzania, Kenya and Uganda, as well as outside Africa.
Ceamellia sinensis, the biological name for the plant
that produces black and green tea, is grown in some 50 countries and is
the world's most widely drunk beverage after water. Apostolides says
tea production in Southern Africa is growing at about 20 percent per
year, so the region could challenge India for first place in tea
production by about 2020. "India produces 900,000 tons of tea per
year," he says, "while Sri Lanka and Kenya, which are always competing
for second place, produce 300,000 tons each, and all the African
countries combined produce about 400,000 tons, so as a region we are in
second place."
The Tea Board of Kenya reported that Kenya's tea exports
last year overtook horticulture – flower production – to become the
country's largest foreign exchange earner. Uganda, Malawi and South
Africa are Africa's other leaders in tea production.
Pelly Malebe's work has included finding a feasible way
to send cultivars to research labs. "Developing countries lack skills
for the isolation of genetic material," she says. "What is needed is a
simple leaf-drying method so that the tea leaves can be transported to
laboratories where genetic material can be extracted and usable genomic
DNA can be isolated and stored."
After testing various methods of drying tea plants –
blanching, pressing, freeze drying and placing it in bags with silica
gel – she determined that using silica gel in sealable plastic bags
gave the best results. That encouraging finding could point the way to
a simple methodology for obtaining and storing genetic material,
applicable to other products and places.
Before publishing her research on DNA markers for
drought resistance, Malebe conferred with Apostolides. The scientists
had to choose whether or not to patent the cultivars. She and her
advisor decided that she would write up the research results without
claiming them as intellectual property. So this breakthrough from
Africa will soon become free knowledge to the international scientific
community.
Story: Ms Julie Frederikse (allAfrica.com.
December 2011), Photography: Prof Zeno Apostolides (UP)
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