The World Health Organisation (WHO) rates micronutrient deficiencies as one of the major public health problems of the developing world.
However, this widespread problem is often under-recognised probably because the symptoms are not immediately obvious and the full impact is long term. For instance, vitamin A deficiency (VAD) leads to night blindness, impaired immune system development and has been linked to impaired brain development. The most obvious symptom of iron deficiency anaemia (IDA) is anaemia and it is a major cause of mortality at childbirth. The prevalence of these deficiencies is often staggering. For instance, in Uganda, close to 30% of the children under five years old have VAD and many more, nearly 80%, have IDA. The rate of IDA in women of childbearing age is also close to 80%.
The most appropriate avoidance of these deficiencies is a varied diet and hence, in the developed world, these deficiencies are rare.
However, in many developing countries where resources for food production are limited, communities tend to depend heavily on a single source of starch such as rice, maize, cassava, bananas, potato, sorghum, taro etc. These communities have usually grown these crops for hundreds of years and there is considerable community knowledge around the production of these crops and often these crops have a strong cultural significance. Unfortunately, in most instances, these "staple foods" are low in one or more of the essential nutrients.
Other strategies such as food fortification, adding the micronutrients to food during or after processing, and supplements have been very successful. They do, however, require constant external inputs. And despite this success there is a proportion of populations in developing countries who are "resistant" to the strategies and that is why these very high levels of micronutrient deficiencies persist. The alternative is to produce varieties or cultivars of the staple food crops with these micronutrients "embedded" in them. This can be achieved through conventional plant breeding and, where this is not feasible for a variety of reasons, through genetic modification. The most advanced of these genetically modified crops is Golden Rice which has been biofortified with pro-vitamin A.
In Uganda, bananas are the staple food with the East African Highland banana, a cooking banana, the primary starch source. As with many starchy, staple foods, these bananas are low in pro-vitamin A, iron and protein and, as a result, banana based diets are low in these nutrients. In Uganda, this poor nutrition manifests as high levels of vitamin A deficiency (VAD), iron deficiency anaemia (IDA) in both children and adults particularly women. This combination of micronutrient deficiencies with bananas as the staple food is not restricted to Uganda, but also occurs in the highlands of Kenya and Tanzania as well as Burundi, Rwanda and eastern areas of the Democratic Republic of Congo.
Genetic improvement of bananas has been a major challenge because cultivated bananas are nearly sterile and conventional breeding, while possible, has delivered only very few acceptable, improved cultivars to replace the selections now grown in nearly all wet tropical and sub-tropical environments. The alternative and achievable strategy for nutrient enhancement of these bananas is through genetic modification. The Queensland University of Technology (QUT), Australia and the National Agricultural Research Organisation (NARO), Uganda commenced a project in July 2005 to enhance the micronutrient content of East African Highland bananas (EAHB) under the Bill and Melinda Gates Foundation's Grand Challenges in Global Health, an initiative that fosters scientific and technological innovation to solve key health problems in the developing world. Grand Challenge 9 is to "create a full range of optimal, bioavailable nutrients in a single staple plant species". Four projects were initially funded: bananas, cassava, rice and sorghum.
The banana project, Banana21, has the key mission of "Alleviating micronutrient deficiencies in Uganda through biofortification of the staple food of Uganda, bananas". Banana21 is lead by Distinguished Prof James Dale and this very competent and enthusiastic team is genetically modifying bananas to enhance the pro-vitamin A and iron content of banana fruit. The initial targets for the project were a four fold increase in pro-vitamin A and a three fold increase in iron. The guiding strategy of this project is to develop the technology at QUT using Cavendish and Lady finger cultivars and transfer the technology (but not the plants) to NARO. The concept is that the micronutrient enhanced bananas for Uganda will be generated in Uganda by Ugandans.By the end of 2011, the project had made excellent progress towards achieving the aims of the project: In short, the project has:
Developed an excellent collaboration between QUT and NARO with the research becoming a fully integrated effort.Genetic transformation of East African Highland Bananas. At the commencement of the project, there was no established method for genetically transforming EAHB at NARO. This was a potential roadblock which has been overcome with the development of an efficient and reproducible transformation protocol.Isolation and characterisation of banana genes. A number of genes from banana involved in either the biosynthesis of pro-vitamin A or accumulation of iron have been isolated and characterised at QUT. One of these genes, a phytoene synthase gene from a high pro-vitamin A banana, Asupina, is currently being used in advanced lines.Promoters. At the commencement of the project, there was very little information regarding the expression of transgenes in bananas particularly in banana fruit and in the field through multiple generations. Sixteen (16) different promoters have been isolated and are being evaluated in the field for expression levels and patterns.First Australian field trial. The first Australian field trial was established in late 2008 in north Queensland. The trial is the first trial in Australia of genetically modified bananas and has more than 1250 different transgenic lines assessment new promoters, different transgene and promoter combinations for elevated pro-vitamin A and different transgene and promoter combination for elevated iron. Already, there are numerous lines with higher levels of pro-vitamin A than the target of a four fold increase.First Ugandan field trial. The first Ugandan field trial was established in 2010 at Kawanda. This is one of the first field trials of any genetically modified crop in sub-Saharan Africa where the plants were generated in a national laboratory. One line already has been identified with levels of pro-vitamin A higher than the target
The vast majority of the bananas currently grown and consumed were not conventionally bred but are selections made over probably thousands of years from naturally occurring hybrids. Cultivated bananas are very nearly sterile and as a consequence are not propagated from seed but rather through vegetative propagation, primarily suckers as well as more recently micropropagated or tissue cultured bananas. These factors, very old selections, near sterility and vegetative propagation, mean that these bananas have not been genetically improved either for resistance or improved quality and are becoming increasing in affected by serious pests and diseases.
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