In Uganda, the local word for food is matooke, which is what the Ugandans call the green banana, their staple food. Nowhere is banana eaten in such a scale as in this East African nation of 31 million.
Ugandans reportedly eat, on average, more than a quarter of a kilogram of banana in a day, or in some areas, 450 kilograms per year! That’s a lot of bananas.
Bananas are as important to the Great Lakes region as rice is to East or Southeast Asia. They are a valuable source of vitamins, minerals, and carbohydrates or calories; they are the primary source of income for 16 million smallholder farmers in Uganda; and they play a central role in the sociocultural fabric of the country.
About one-third of the total global banana production comes from sub-Saharan Africa where millions of subsistence farmers and consumers depend on the crop as a staple food. Bananas are easy to grow especially in the Great Lakes region where growing conditions for the crop are ideal.
But banana production in the region is being threatened by a complex of pest and disease problems, including Fusarium wilt (Fusarium oxysporum f.sp cubense), black leaf streak or sigatoka (Mycosphaerella fijiensis), viruses, banana weevils (Cosmopolites sordidus), and nematodes (e.g., Radopholus similis). The most serious threat at the moment is banana Xanthomonas wilt (BXW, Xanthomonas vasicola pv. musacearum), which could devastate the banana industry in East Africa. These pests and diseases damage the banana plants, cause yield loss, and eventually food insecurity and loss of livelihoods.
With the food security and livelihood of millions of farmers at stake, science and industry meet to save the crop and develop technologies to make production more sustainable. One technology involves the rapid, mass propagation of more robust bananas using endophyte-enhanced tissue culture,â€ said Thomas Dubois, biocontrol specialist and nematologist based in Uganda, who leads the team of IITA scientists that helped develop the technology.
Tissue culture is not a new technology. Tissue-cultured banana is the norm in the rest of the world. Commercial tissue culture laboratories are beginning to emerge across East Africa to satisfy the rapidly rising demand for healthy planting material.
Tissue culture banana plants made in specialized private-sector laboratories are healthy and can grow faster than traditional plants. They are also ideal for establishing large plantations, which are then uniform, enabling better planning for harvests and marketing.
Tissue culture produces clean plantlets without disease but also without a natural defense system. They are quite sensitive to the relatively harsh conditions in the East African fields, including attack by pests and diseases, and low soil fertility. The smallholder fields are burdened with biotic pest pressures and abiotic constraints, and the small-scale farmers do not practice essential high-input field maintenance. Thus, tissue culture adoption in Africa faces a â€œbarrierâ€.
This is where IITA came to the rescue. â€œEndophytesâ€ is a general term for naturally occurring microorganisms inside the plant that protect it from pests and diseases, and that enhance plant growth. Every single individual plant species, including banana, contains endophytes. They can be used as a natural form of control. Introducing endophytes in plants during propagation is like immunizing them. Plants inoculated or â€œvaccinatedâ€ with endophytes become resistant to pests or diseases.
Army against pests and diseases
The endophytes become part of the planting material before the young tissue culture plants are sold to farmers. Once inside, the endophytes go to work, boosting the plantâ€™s immune systemâ€”so long as they get there first, before the pathogen.
Thus, farmers are provided with a weapon to fight the banana weevils and nematodes, which abound in the soil and which are transferred by farmer-to-farmer contact through exchange of infected planting material.
IITA, through its station in Kampala, Uganda, developed the endophyte technology to produce robust pest- and disease-free banana planting material, in collaboration with various national and international partners. Research on this technology started in 1997 with funding from the German Federal Ministry for Economic Cooperation and Development (BMZ).
IITA isolated nonpathogenic strains of endophytes belonging to the Fusarium family from healthy plants growing under high levels of pest and disease pressure. Institute scientists developed a rapid, easy, and low-cost laboratory screening protocol for testing the numerous endophyte strains obtained against the banana weevil and the burrowing nematode. They also devised a more efficient technique to mass produce the best strains, and introduce them into the tissue-cultured plantlets. The endophyte-enhanced plants are then grown in screenhouses and in farmersâ€™ fields to assess their performance against target pests.
Using endophytes as biological control agents offers several advantages. When endophytes enter the plants first, they get a head start over the other microorganisms, and once they are established, other microorganisms would offer less competition. Because the endophytes are already in the plantlets when they are transplanted, control can be targeted using low levels or doses, and performance is consistent. Using endophytes also makes it easier to control cryptic pests such as the banana weevil and the burrowing nematode, which are embedded within plant tissues.
As an off-shoot of work on endophytes, IITA-Uganda scientists realized that endophytes circumvent many of the barriers associated with conventional biopesticides. This has spurred novel research in using conventional biopesticides, such as Beauveria bassiana, as artifical endophytes in seed systems. B. bassiana worldwide is the most researched and commercialized fungal biopesticide against a variety of insect pests.
Laboratory and screenhouse studies have revealed the great potential of this entomopathogenic fungus for use against the banana weevil. However, impractical field delivery methods and high costs associated with its application prevent its use and commercialization in banana fields.
IITAâ€™s research also showed that B. bassiana can â€œcolonizeâ€ the internal banana tissues for at least four months and that B. bassiana-enhanced plants reduced larval damage by more than 50%. It kills the damaging insect stages inside the plant; it is protected from adverse biotic and abiotic factors; little inoculum is required, greatly reducing cost. Farmers do not need to apply the biological control organism themselves, as the technology is easily transferable to a commercial tissue culture producer.
But IITAâ€™s research-for-development work does not end there. How does IITA make endophyte-treated plantlets available to farmers, the ultimate users of the technology, as a ready-to-plant product at low cost?
Confluence of science and industry
The Institute has established strategic alliances with several private and public sector entities to develop international public goods. It leads the research effort on endophyte-enhanced tissue culture technology, and a commercial tissue culture entity and a private biocontrol company handle the formulation, distribution, application, and storage of the plantlets. In the process, IITA and its partners are helping commercialize the banana industry in East Africa.
Endophyte-enhanced banana tissue culture research is undertaken with research partners that include the University of Bonn, Germany; the National Agricultural Research Organization (NARO), Uganda; the University of Pretoria, South Africa; Makerere University, Uganda; Wageningen University, the Netherlands; the Catholic University of Leuven, Belgium; and the Biologische Bundesanstalt fur Land-und Forstwirtschaft, Germany.
The work though is not confined to banana production in Africa. Bioversity International, in collaboration with IITAâ€™s German partners, is testing endophyte-enhanced tissue culture with large-scale banana producers in Costa Rica, using Latin American endophyte strains.
Since IITA does not have the in-house capability to undertake large-scale endophyte-based research in its facilities, the Institute partnered with several private and public organizations involved in tissue culture: Agro-Genetic Technologies (AGT), a commercial tissue culture laboratory in Uganda; Jomo Kenyatta University of Agriculture and Technology (JKUAT) and RealIPM, a biopesticide company in Kenya.
An exploratory and collaborative effort to produce more robust tissue culture plantlets as research material has developed into a synergistic partnership that bridged upstream research and downstream application. On the other hand, linking up with large-scale tissue culture producers in Uganda and Kenya have helped refine and move the technology from the lab to the farmers themselves.
Through collaboration, endophyte-enhanced technology is now being tested in farmersâ€™ fields in East and Central Africa. The technology enables the farmers to switch from subsistence to income generation, and more importantly to reach and create markets.
Following the research-for-development model, IITA and its partners realized that engaging and mobilizing the community of farmers is essential for the technology to succeed and gain wider adoption.
IITA saw the value of harmonizing public-private sector collaboration at the early stages of the project. It has adopted this approach in its R4D work in Africa, and is promoting its application in technology transfer work in other areas of research, mandate crops, and commodities.