Nematode resistant plantain for African subsistence growers

The former secretary general of United Nations, Kofi Annan, called for a uniquely African Green Revolution in 2004. The need is to counter severe under-nourishment in nearly one third of the sub-Saharan African population. He and eight leading economists including three Nobel laureates recognised the potential of biotechnology to enhance food security. A key issue is African dependence on crops such as plantain. It is not often studied by plant breeders in the developed world. Plantain and other cooking forms of banana provide 27% of the daily calorie intake of Ugandans and 25% of the carbohydrates of 60 million people in West Africa. Most plantains are sterile and produce no seeds. This hampers their improvement by conventional plant breeders. This sterility enhances the biosafety of plant biotechnology involving this crop. The need is considerable as plantain is highly vulnerable to severe crop loss from diseases and pests. This issue has been highlighted by news media. This project will provide nematode resistant plantains for Africa. Nematodes are simple thread-like animals of less than 1mm in length that feed in plant roots. Experiments in several African countries show their abundance often results in yield losses of 70% to plantain. Chemical control of nematodes is currently required for most plantations of dessert banana. We will reduce losses to banana with an approach that provides an alternative future to increased pesticide use. Three bases for providing resistance will be used in combination to provide high levels of durable resistance in the field. Two approaches are available 'off the shelf'. All draw on outputs from other BBSRC funded research and build on previous work for DFID. The approaches offers a high level of environmental and food safety. Scientists in Uganda will produce all the new plants so enhancing the ability of that country to complete such work. Levels of resistance will be determined that prevent nematodes from damaging plant growth. All necessary information will be collated for the Uganda national biosafety committee to consider consent for field trials. This has already been granted for other banana plants. The project links to other work providing resistance to fungal and bacterial diseases for plantain and bananas. The combination of benefits can be delivered sooner by biotechnology than possible by conventional plant breeding. The work will demonstrate that plant biotechnology can benefit the poor in Africa. It meets a real need for nematode control that is recognised by its farmers. Nematode resistance is required for other subsistence crops of Africa that will be addressed later using the same technology. The project avoids the general concern of some that biotech crops require dependence of the developing world on the products, patents or licences of biotechnology companies. The partners of this project have a long-established commitment to royalty-free biotech crops for Africa. The work seeks to establish that public research for public good can develop benefits for the poor in Africa in support of the Millennium Development Goals. Plantain represents a biosafe crop on which to develop the necessary capacity. We seek to enable African science to support all aspects of biotechnology and biosafety that can support national aims to enhance food security. In-country capacity in plant biotechnology is necessary before African countries can make realistic assessments of what they can and cannot achieve that meets national needs.

The work is based on Agrobacterium-mediated introduction of genes to plantain by a novel technique of apical meristem transformation. This avoids slow regeneration of plants from single cells that may result in unwanted somaclonal variation. The approach has been developed by the co-applicant within Africa. Initial work will use constructs providing expression of a maize cysteine proteinase inhibitor already present in the food of Africans. It prevents nematodes from utilising their dietary protein without harmful effect on humans and controls a wide range of plant nematodes including those that damage plantain. Toxicological studies establish a margin of exposure is >2000 fold when root specific promoters are used to deliver a cystatin. UK field trials have established no substantial adverse effect either on invertebrate associates of a potato crop above ground or on soil communities. The cysteine proteinase inhibitor will be stacked with a non-lethal, synthetic peptide that limits root invasion by nematodes. The work will also adapt other research for BBSRC that is expressing a double stranded RNA in plants. This results in the silencing of a gene that the nematode requires to survive or develop in plants. This effect was first reported in detail for a nematode and resulted in the award of the Nobel Prize for Medicine for the advance it provides. In the context of the current work, the lack of new protein expression in plants overcomes the concerns of expression of even biosafe, novel plant proteins in biotech crops. The levels of resistance required to prevent nematode mediated growth suppression of plantain that lead to yield loss will be determined. This and other information will be collated and permission sought for field trials in Uganda. All the objectives of the work combine to enhance the capacity for Uganda to develop biotech crops in country to meets its national needs and objectives.