Highlights - Eastern Africa
Aflatoxins are produced in a range of staple crops by the fungus Aspergillus flavus and A. parasiticus, both in the field and during storage. To improve the health and livelihoods of farming families and consumers in Africa, we partnered with the United States Department of Agriculture’s Agricultural Research Service (USDA-ARS) and the African Agriculture Technology Foundation (AATF) to develop aflasafe™, a natural, safe, and cost-effective biocontrol product that cuts aflatoxin contamination in food crops by as much as 90%.
Aflatoxins are highly toxic chemicals that suppress the immune system, impede growth and development, and cause liver disease and even death. Children and the poor are usually the most affected. Because of these recognized health risks, aflatoxins are heavily regulated in international shipments.
Biocontrol trials to manage aflatoxin in Kenya have led to Kenya developing its own brand of aflasafe™. Registration is ongoing and the trademark “aflasafe-KE01TM” has been approved under the Kenya Industrial Property Institute (KIPI) and a laboratory at KARI-Katumani has been renovated to advance mycotoxin research within the national program.
The aflasafeTM program has also been expanded to Tanzania where prevalence studies of mycotoxin in maize and cassava were completed in 2012 in collaboration local and international partners. A key component of the project was to raise awareness of the harm that aflatoxins can cause. To achieve this, we developed and distributed factsheets in Swahili to 2500 farmers and market vendors who supplied crop samples for aflatoxin testing, as well as 600 factsheets in English to other traders and district and regional extension officers.
Two ways to tackle the dual threat on cassava
Farming communities in East Africa rely on cassava as a food security crop and for generating cash income, but they are continually faced with the challenges of the virus diseases CMD and CBSD. The two main approaches to managing these problems are through germplasm development and crop health management.
This is done via conventional breeding, and using molecular marker development, and transgenic methods. Breeding trials are being carried out in Tanzania, Uganda, and Zanzibar to develop dual-resistant varieties and characteristics preferred by farmers.
We are working with the national programs in Tanzania and Uganda to find molecular markers (or tags) associated with resistance to CBSD in six cassava varieties for use in marker-assisted breeding. Approaches being used include quantitative trait loci (QTL) mapping and gene expression studies.
As known sources of resistance are difficult to introgress into farmer preferred cultivars by conventional methods, the integration of resistance traits via transgenics holds significant potential to address CBSD. Of the available biotechnological approaches to control plant viral diseases, RNAi is a very promising strategy.
We are collaborating with the Donald Danforth Plant Science Centre (DDPSC) to develop CBSD-resistant cassava for preferred cassava cultivars in East Africa. In introducing CBSD resistance we have made attempts towards developing protocols for the transformation and regeneration of cassava plants through somatic embryogenesis. The transformation system has already been established at IITA for three cultivars preferred by African farmers and this will be extended to other cultivars.
Crop health management
All cassava varieties, whether research-bred or traditional farmer-grown, can benefit from basic phytosanitary measures that aim to maximize the health of planting material and minimize the level of infection by pathogens. We have begun working closely with NARS, NGOs, and commercial partners in the region to establish sustainable cassava “clean seed” systems that make use of formal certification standards, including virus testing. Farm-level management of cassava health is being further strengthened by our support to a pilot-level community phytosanitation project being led by NARS in Tanzania.
Keeping Banana Xanthomonas Wilt (BXW) in check
Banana Xanthomonas Wilt (BXW) is threatening banana production across the Great Lakes region of East and Central Africa. No banana cultivar has resistance to the disease, yet the people of this region are highly dependent on the crop for food security and income generation.
In collaboration with national research and regulatory partners, we led regional surveillance initiatives to map the presence and spread of BXW. Once the disease is confirmed in a location, disease awareness campaigns are mediated through SMS (text messaging), factsheets, booklets, radio messages, and community-based action to identify and manage the disease through cultural practices. However, the level of BXW control by cultural practices can be inconsistent as it is dependent on the individual growers and traders implementing them.
A more effective solution is to develop cultivars that are resistant to the disease. Our researchers, in partnership with NARO-Uganda and AATF, have done that by using transgenic lines of banana containing genes from sweet pepper that confer resistance against BXW. The transgenic banana plants have exhibited strong resistance to BXW in the laboratory and screenhouse tests. Twelve transgenic lines have been found to be completely resistant to BXW after the evaluation of three generations of crops. Furthermore, the transformed lines also showed characteristics of flowering and yield (bunch weight and fruit size) comparable to those of non-transgenic varieties.
Given the rapid spread and devastation of BXW across the continent, genetic transformation through the use of modern biotechnology tools offers―at least for the time being―the most effective, fast, safe, and viable way to develop resistant varieties and help save the livelihoods of millions of smallholder banana growers.