Gumtree could be a lifeline for Kenyan farmers

17 November 2009, by Tamera Jones

Scientists have found a wide range of genes in a native Kenyan tree, Acacia senegal. They now hope to take advantage of this diversity by finding trees with the best qualities to help Kenyan farmers turn a tidy profit from the gum arabic resin the trees produce.

Acacia

Acacia senegal var. kerensis at Ngare Ndare, Kenya.

If the researchers succeed, this will be welcome news for the country's farmers, whose cattle struggle in serious droughts like the one Kenya recently experienced.

In the dry north of the country, most farmers make their living from livestock - mainly cattle. Many are keen to find alternatives to livestock farming, because cattle don't do well during droughts.

The problem is particularly pressing, because under climate change, desertification and dryness are set to get worse in this part of the world. If farmers have alternative ways of making money, other than by selling cattle, they'll be much better off.

Acacia senegal is a remarkable tree - its home is the drylands, so it needs very little water to grow, which means drought isn't a problem.
Dr Stephen Cavers, Centre for Ecology & Hydrology

"Acacia senegal is a remarkable tree - its home is the drylands, so it needs very little water to grow, which means drought isn't a problem. In fact, when it's under stress, it produces more gum," says Dr Stephen Cavers from the Centre for Ecology & Hydrology, who took part in the project.

The scientists hope that by finding trees with the ability to make lots of good quality gum, they can help Kenyan farmers to grow trees they can profit from, even in hard times. "At the moment, in countries like Sudan, farmers collecting gum can make the equivalent of a month's salary in one day," adds Cavers.

The trees naturally ooze gum arabic, a valuable glue-like resin used since Ancient times. The gum is still used widely in the food, pharmaceutical, cosmetics and printing industries.

It's harvested commercially from wild trees throughout the Sahel, from Senegal, Sudan and Somalia. Sudan is the biggest producer of the gum, exporting to countries all over the world.

High quality gum

But industry has recently focused its attention on a Kenyan variety of the tree which produces particularly high quality gum.

"There's a lot of potential for the market to grow in Kenya. If we can breed trees that produce both good quality gum and lots of it, there's no reason why Kenya can't be the next Sudan, because it's got plenty of the trees and the gum it produces is very high quality," says co-author Dr David Odee from the Kenya Forestry Research Institute.

The land in this region of Africa is threatened by unsustainable agriculture, deforestation, over-grazing and climate change, 'and understanding how the trees' genes vary across the country is a prerequisite for the management of natural populations,' says Cavers.

"Up until now, dryland forests, which are home to Acacia senegal have been badly hammered. Local people use the wood for charcoal and firewood. But if it's farmed sustainably, not only will farmers profit, but the tree is more likely to survive," he adds.

Cavers and his team hope that by understanding how genes move around in Acacia senegal forests across Kenya they can also help to target efforts to conserve the species.

They report in the journal Tropical Planet Biology how they analysed the DNA from Acacia senegal var kerensis trees across the whole country.

They found that although the trees' genes varied a lot within populations, differences between populations were small. "Northern Kenya has a savannah landscape. It's open and windy and there are a lot of large, migrating animals, so pollen and seeds move around a lot," explains Cavers.

The team identified two main populations - in the Rift Valley and in Eastern Kenya - reflecting the influence of geography on seed and pollen dispersal.


Tropical Plant Biology Genetic Diversity and Population Structure of Acacia senegal (L) Willd. in Kenya - Stephen F Omondi, Eliud Kireger, Otto G Dangasuk, Ben Chikamai, David W Odee, Stephen Cavers and Damase P Khasa

Received: 11 September 2009 Accepted: 22 October 2009 Published online: 12 November 2009
DOI: 10.1007/s12042-009-9037-2