Numerous communities in developing countries depend on bananas as a staple food and as a source of income. The vast majority of producers are smallholder farmers who grow most of the world production, estimated by the FAO to be more than 125 million metric tons in 2008. Less than 15% of global production is exported.
Bananas are unusual among major crops in that most of the types grown, either for export or local consumption, are farmer-selected varieties rather than improved hybrids produced by breeding programmes. This situation reflects not only the difficulty of breeding bananas, but also a general lack of appreciation of its importance as a staple crop.
The funds invested in banana research in general are still not commensurate with the importance of the crop and the scale of the problems faced by smallholder producers. Meanwhile, the genetic base on which solutions to these problems depend — either through genetic improvement or a better use of diversity in production systems — is being eroded. Reducing diversity, in turn, has made the crop even more vulnerable to pests and diseases, forcing farmers who have little means for combating them to give up on the more susceptible varieties.
But while the production and marketing of this crop pose many challenges, they also present great opportunities for improving the welfare of farmers and consumers in developing countries. Enabling farmers across the tropics to use biodiversity to meet their food security needs and livelihoods aspirations are the main goals of Bioversity International’s work on bananas.
The mission of Bioversity’s banana research group, with headquarters in France and regional offices in Costa Rica, the Philippines, Cameroon and Uganda, is to help people, especially small-scale banana producers and their communities, to improve their well-being through effective use of banana biodiversity.
Banking on Musa
Bioversity’s approach to research along the banana commodity chain begins with the conservation, within the public domain, of the world’s largest in-vitro collection of Musa. The collection, which contains more than 1,300 accessions, is held at the International Transit Centre (ITC) hosted by the Katholieke Universiteit Leuven (KULeuven) in Belgium.
At the time of its establishment in 1985, quarantine regulations were putting a constraint on germplasm movement. Indexing methods were developed and virus-indexing centres were set up. By the late 1980s, the system to allow the safe movement of germplasm was in place. All the accessions are routinely virus-indexed, and virus therapies have been developed by partners at the University of Gembloux and the French agricultural research institute CIRAD. Virus research commissioned from CIRAD and the University of Minnesota has improved the understanding of banana streak viruses, but their presence in 30% of the collection continues to restrict this part of the collection from general circulation. The ITC has established a collection of lyophilized leaf samples to respond to demands for DNA. By this means, even accessions that are virus-infected can be made available for molecular study.
An extra level of insurance is provided by the conservation of accessions in liquid nitrogen. At these ultra-low temperatures, so-called ‘cryopreservation’ arrests both the growth of plant cells and all processes of biological deterioration, so that the material can be preserved, safely and cost-effectively, and regenerated into fully viable banana plants. So far, most of the collection has been safely cryopreserved and, as yet further insurance, a duplicate set is being deposited for safe-keeping at the French research institute for development IRD.
A Global Conservation Strategy for Musa was developed with partners. Building upon existing strengths at the ITC, and several regional and national collections, the strategy aims to rationalize the global effort to conserve the Musa gene pool and promote the wider use of these genetic resources by scientists, farmers and breeders to produce new varieties.
Bioversity works with specialist research institutes to identify the useful traits embodied in these genetic resources. For example, the ploidy level of the ITC accessions has been entirely characterized by the Institute for Experimental Botany (IEB) in the Czech Republic, using flow cytometry. Another key role is to set up information systems to disseminate the data generated by these characterization and evaluation activities and to make research results available to a wide public.
Hungry for improvement
Bananas are known to be difficult to breed. The first ones to try gave up. When the United Fruit Company also abandoned the idea of breeding a commercial banana in 1984, it donated its breeding programme to the Fundación Hondureña de Investigación Agrícola (FHIA) in Honduras, which, capitalizing on more than 25 years’ worth of work on bananas, was soon able to deliver disease-resistant hybrids.
Before they were released, the hybrids were field-tested in the International Musa Testing Programme (IMTP) set up in 1989 and coordinated by Bioversity. One of the explanations offered for the slow progress of banana breeding had been that breeders were receiving little guidance from other disciplines. The IMTP addressed this by making the material they produced available for study by pathologists and other scientists under different environmental conditions.
Forging inter-disciplinary links was further encouraged with the creation in 1997 of the Global Programme for Musa Improvement (ProMusa). At the origin, it consisted of six interlinked working groups, each focusing on a particular subject—genetic improvement, Fusarium wilt, Mycosphaerella leaf spot diseases, weevils, nematodes and viruses—but all from the point of view of providing support to banana breeding efforts. It has since been restructured to further stimulate interaction among specialists and to take into account the difficulty of coordinating such a network with minimal financial support from donors.
Indeed, it has proved increasingly difficult to attract the interest of donors to conventional breeding efforts as a whole. Funding for the IMTP dried up after the first phase (phases II and III were funded by the implementing partners) and public-sector support to FHIA ended in 2004. The lack of international donor interest in networking has however not spelled the end of banana breeding. The field is not as crowded as for the other major crops, but a handful of centres are still at it. In Latin America and the Caribbean, the veterans are the Empresa Brasiliera de Pesquisa Agropecuaria (EMBRAPA) and CIRAD’s Guadeloupe research station. Cuba has also started its own banana breeding programme at the Instituto de Investigaciones en Viandas Tropicales (INIVIT). In India, the National Research Centre for Banana (NRCB) and Tamil Nadu Agricultural University have created numerous hybrids, while in Africa, banana breeding is mainly conducted by the International Institute of Tropical Agriculture (IITA) and the Centre de Recherches Regionales sur Bananiers et Plantains (CRBP).
Given the difficulties inherent in breeding bananas, some scientists have turned their sights to genetic transformation as a way of introducing genes into bananas without disrupting their agronomic qualities. Moreover, the lack of cross-fertile wild relatives in many banana-producing areas and the sterility of most cultivated varieties reduce, to negligible levels, the risk of genes escaping from genetically-transformed bananas. Over the years, Bioversity has coordinated research projects that have contributed to advances in genetically modifying varieties important to smallholders.
Meanwhile, a networking approach is helping researchers make the most of the rapid progress in genomics. Since 2001, most of the genomics work on bananas is being done by scientists who are members of the Global Musa Genomics Consortium (GMGC), for which Bioversity provides the secretariat. Whenever possible, the products developed by GMGC members are placed in the public domain and available from the Musa Genome Resources Centre hosted by the IEB. The sequencing of the genome being done by the French National Sequencing Center, Genoscope, will help identify and use genes of interest for breeding, as well as facilitate parent choice.
Bioversity and its partners have looked at many dimensions of the challenge of producing slowly evolving bananas in a rapidly evolving world. In other crops, the conventional wisdom is that pest- and disease-resistant varieties provide a sound foundation for integrated crop management strategies but in bananas this principle has been hard to establish. Farmers and consumers have tended to develop strong preferences for their familiar cultivars and, because of the complexity of banana breeding, the disease-resistant cultivars that have been developed rarely substitute directly for existing varieties.
Access to good quality planting material can also be an issue limiting adoption of the new cultivars. Bioversity-led efforts to disseminate improved hybrids in Latin America, Africa and Asia took care to ensure the quality of the initial planting materials and, to some extent, set up mechanisms to encourage further propagation of the new materials by conventional methods. However, these experiences fall far short of establishing national systems to ensure the long-term availability of clean planting material.
However, Bioversity has worked on institutionalizing such systems in Asia where 17 National Repository, Multiplication and Dissemination Centres have been established in 14 countries. These Centres maintain disease-free mother stocks of potentially useful varieties that can then feed into private- or public-sector systems for larger-scale multiplication. This involves many complementary actions, most successfully undertaken in the Philippines, where a partnership between highly efficient private sector producers of tissue-culture plants (mainly for the export industry) and public sector providers of expertise have teamed up to supply large numbers of high quality plants to small-scale farmers at very competitive prices.
Lacking the foundation provided by the banana export industry, smaller-scale tissue-culture laboratories in East and Central Africa provide plantlets at approximately four times the price of their counterparts in the Philippines. Moreover, the upgrading of such systems to ensure quality plantlets at a competitive price represents something of a ‘chicken-and-egg’ situation—in so far as suppliers’ ability to achieve economies of scale depend on an increased demand but it is hard for demand to grow as long as the supply is inadequate.
Part of the demand side of the equation would appear to be the market for processed products. For instance, in East Africa there are indications that improved hybrids can provide an acceptable and profitable supply of raw material for the traditional banana beer-brewing and wine-making industries. In Latin America and elsewhere, the new varieties serve as raw materials for making plantain chips, which have a limited but profitable market as a snack food. Bananas also serve as a raw material for a wide range of flours, ketchups and various high-value confectionary products.
Supplying factories or even urban markets with a dependable supply of bananas presents smallholder farmers with quite a different challenge from their traditional one of assuring household and community food security. Varieties remain an important consideration in this new market-oriented game, but production systems that offer high productivity and predictability are also at a premium. Unit sales price for processing is usually lower than for fresh market which also puts great pressure on production costs.
One approach that Bioversity has been experimenting with in both Latin America and Africa involves high-density annual planting particularly of plantains and some cooking bananas. By re-planting annually with clean planting material—and, if necessary, rotating with other crops—farmers may be able to reduce problems of chronic, soil-borne pests such as nematodes, while increasing the productivity of limited land holdings. The dense shade that is established by the banana plants effectively reduces weeds while, through mechanisms that are poorly understood, a microclimate seems to be established that under certain conditions can reduce the incidence of black leaf streak.
The high cost of synthetic pesticides and growing resistance of the pathogen to conventional products remain strong incentives for the development of new products and approaches. And how can we harness biodiversity to sustainably enhance the productivity and resilience of farming systems? This includes research on soil and root health and on the threats posed by epidemic diseases, as well as advocacy to develop concerted action in response to such threats. Projects in Latin America have looked at a wide range of plant and compost extracts for their effectiveness in reducing pathogen attack, either by boosting the plant’s defence mechanisms or through direct toxicity to the fungi. Researchers are also finding that bacteria and fungi living ‘endophytically’ within the tissues of plants without causing disease may help to protect the host plant against disease-causing agents.
Bioversity pursues many of these actions through four regional research-for-development networks: MUSALAC in Latin America and the Caribbean, BAPNET in Asia and the Pacific; BARNESA in Eastern and Southern Africa, and the Innovation Platform for Plantains in West Africa. The networking approach of Bioversity is ideally suited to mobilizing the complementary resources of partners in these concerted global efforts. Its trademark approach of sharing knowledge and the task of testing new options is ideally suited to identifying a range of solutions, tailored to the individual situations and aspirations of the small banana producers and their communities.
Guest blog by Inge van den Bergh, Stephan Weisse, Anne Vezina and Nicolas Roux for Bioversity International.