Genetically modified bananas are cultivated for disease resistance and nutrition
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Peer-reviewed literature establishes that genetic modification techniques are applied to bananas to develop improved agronomic traits such as disease resistance and to address nutritional and food security goals.
Background: Credible empirical evidence is scanty on the social implications of genetically modified (GM) crops in Africa, especially on vegetatively propagated crops. Little is known about the future success of introducing GM technologies into staple crops such as bananas, which are widely produced and consumed in the Great Lakes Region of Africa (GLA). GM banana has a potential to control the destructive banana Xanthomonas wilt disease. Objective: To gain a better understanding of future adoption and consumption of GM banana in the GLA countries which are yet to permit the production of GM c
440 plosone PLoS ONE PLoS One PLOS PMC4587572 4587572 4587572 26414379 10.1371/journal.pone.0138998 Ex-Ante Economic Impact Assessment of Genetically Modified Banana Resistant to Xanthomonas Wilt in the Great Lakes Region of Africa Ainembabazi John Herbert 1 * Tripathi Leena 2 Rusike Joseph 3 5 Abdoulaye Tahirou 4 Manyong Victor 3 Lee Seon-Woo Editor 6 1 International Institute of Tropical Agriculture (IITA), Kampala, Uganda 2 International Institute of Tropical Agriculture (IITA), Nairobi, Kenya 3 International Institute of Tropical Agriculture (IITA), Dar es Salaam, Tanzania 4 International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria 5 Alliance for a Green Revolution in Africa (AGRA), Nairobi, Kenya 6 Dong-A University, REPUBLIC OF KOREA Competing Interests: The authors have declared that no competing interests exist.
Introduction Investments in biotechnology development are leading to the introduction of genetically modified (GM) crops with significant impacts on yield improvement, poverty reduction and food security. These impacts have been assessed using ex post and ex ante analyses [ 1 – 11 ]. Finger et al. [ 12 ] and Klümper and Qaim [ 13 ] demonstrated impressive impacts from GM crops: a significant reduction in pesticide use, yield gains and increased profits for farmers. Genetic modification of staple food crops such as banana and rice for resistance to diseases, pests and abiotic stresses can be expected to substantially alleviate poverty, hunger and malnutrition [ 10 , 14 ].
Increasing the productivity and profitability of production are important steps in achieving household and national food security and driving down the real price of food to accelerate economic growth, increase the sustainable management of natural resources, improve nutrition and health and reduce poverty. However, banana production is being seriously threatened by the outbreak and spread of BXW [ 19 ] caused by Xanthomonas campestris pv. musacearum (Xcm). BXW affects both the quantity and quality of fruits. Crop losses can be as high as 100%. Currently, two major approaches exist to control the disease.
First, the use of cultural practices, which involves removing the male bud (to prevent infection carried by insects), using sterilized farm tools and destroying single infected stems (or the whole mat). However, the level of BXW control by cultural practices can be inconsistent when the value chain actors, especially the farmers and traders, fail to comply in implementation. The second approach would be to use natural host plant resistance to prevent the disruptive impacts of BXW but this is non-existent in the germplasm of cultivated banana.
These proteins are widely distributed across a broad range of plant species including vegetables that are, like sweet pepper, eaten raw. Importantly, the risk of gene escape to other crops is unlikely since most edible bananas are sterile and the process involves clonal propagation which limits gene flow to other crops. The GM banana plants have been evaluated in Uganda and have shown absolute resistance to Xcm [ 22 , 23 ]. The transgenic lines showed flowering and yield characteristics comparable to non-transgenic varieties and are currently under evaluation for the durability of disease resistance and agronomic performance in the second field trial in Uganda.
This potentially leads to a vicious cycle of BXW occurrence on farmers’ fields—in the sense that, after all infected plants or mats have been removed; the new planting material remains a potential source of infection. Fig 1 Farmers’ awareness of BXW disease in target countries. Fig 2 Losses in banana production due to BXW incidences in target countries. Table 2 Control methods for BXW and awareness of genetically modified (GM) crops.
The most important potential disadvantages included the following: the GM banana may lead to the outbreak of new diseases through mutation, which may lead to major losses of local varieties and establishing new plantations incurs a high cost. This is likely to slow down early adoption of GM banana since farmers have
More than half (56%) of the respondents, on account of the high market demand and limited choices, perceived that all consumers would not select against GMB-BXW but would be more concerned about consumption attributes than the type of variety (Figs 7 and 8 ). When urban and rural (farmers) consumers are compared, the former would be the main consumers (24% against 13%) as the price is more important to them than the variety. Very few (7%) would not consume GMB-BXW owing to perceived negative attitudes toward GM crops. These results further underscore the importance of preserving or enhancing the quality and taste of banana when breeding for disease and pest resistance.
Results not reported but available from authors on request revealed that reducing (increasing) the discount rate by 50% would increase (reduce) the NPV values for each country reported in Table 6 by at least twice as much. This suggests that significant changes in economic environment and/or monetary policies such as interest rates may have serious implications on the benefits derived from the adoption of GMB-BXW. Conclusions Banana production has been greatly affected by BXW in the GLA. The existing management practices to control the disease reduce the effects to only a small extent.
mber mosaic virus (CMV) to efficiently silence target genes. This system might be useful for gene functional analysis in bananas before stable genetic transformation. In summary, the application of various genome editing systems may lead to banana germplasm innovation and additional functional genomics studies of various agricultural traits. Challenges and Future Possibilities for the Development of Banana Cultivars With Fusarium Wilt Resistance and Ideal Plant Architecture
Bananas are the fourth most important crop in developing countries after rice, wheat, and maize; these crops are important for food security ( Dash and Rai, 2016 ). The most destructive threat to banana production is Panama disease, caused by Foc . Because Fusarium cannot be controlled by any chemical or physical means once established, sustainable banana production requires the use of Foc -resistant varieties ( Heslop-Harrison and Schwarzacher, 2007 ). In addition to disease resistance, banana production can also be improved by the development of bananas with IPA ( Khush, 2001 ; Wang et al., 2017 ). Banana plants with ideal architecture (e.g., dwarfism, strong stems, more upright leaves, and root systems with excellent hydrotropism) would have improved light and water utilization efficiency, lodging resistance, yield, and disease resistance under the current dense planting schemes ( Dash and Rai, 2016 ; Wang J. et al., 2018 ). It is extremely difficult to develop new banana varieties by conventional breeding methods, due to the sterility, polyploidy, and parthenocarpy of most banana cultivars ( Michael and Abdou, 2011 ). Genetic modification, which compensates for the lack of traditional breeding opportunities, is an effective way to develop bananas with improved agronomic traits, such as increased disease resistance and yield.
Two major challenges face banana breeders aiming to produce genetically modified banana varieties with Foc resistance and no yield penalty. First, genes associated with F
Introduction Bananas ( Musa ssp.), which originated in Southeast Asia, are widely cultivated throughout the tropics and sub-tropics, where they represent part of the staple diet and are a vital source of nutrition for over 500 million people ( Wang et al., 2019 ). Due to their widespread popularity, bananas have the largest market share of any fruit worldwide ( Langhe et al., 2008 ). Because bananas are nutritious and starchy, they are considered the fourth most important food crop after
There is no effective chemical or biological control for TR4 ( Dita et al., 2018 ). As commercially cultivated bananas are sterile and propagated via vegetative suckers, it is not possible to use conventional cross-breeding methods to develop resistance to this fungus. Therefore, global banana production may be seriously devastated by Foc in the future unless genetically modified varieties with TR4 resistance are developed ( Maxmen, 2019 ). Several genes that have been used in attempts to develop Foc TR4 resistance in bananas are listed in Table 1 .
In glasshouse trials, “Lady Finger” banana plants that had been transformed with various animal genes associated with apoptosis-inhibition [e.g., B-cell lymphoma-xl ( Bcl-xL ), Cell death protein-9 ( Ced-9 ), and Bcl-2 3′ untranslated region (3′ UTR)] exhibited improved resistance to Foc Race 1 ( Paul et al., 2011 ). Similarly, transgenic bananas modified with the Ced9 anti-apoptosis gene from the nematode Caenorhabditis elegans showed improved resistance to TR4 in the field ( Dale et al., 2017 ). Banana-derived pathogen-resistance genes have also been used to increase disease resistance.
Using the complete banana genome and the developed ECS methods, whole-genome CRISPR/Cas9 mutant libraries can be constructed for target gene mining, functional gene analysis, and genetic improvement in bananas. In the future, a combination of functional genomic and genetic transformation techniques may lead to the development of improved banana varieties, with both excellent disease resistance and high yield. Methods of Genetic Transformation Banana breeding programs generally aim to improve disease resistance, stress tolerance, yield, and plant architecture ( Dash and Rai, 2016 ).
In summary, the application of various genome editing systems may lead to banana germplasm innovation and additional functional genomics studies of various agricultural traits. Challenges and Future Possibilities for the Development of Banana Cultivars With Fusarium Wilt Resistance and Ideal Plant Architecture Bananas are the fourth most important crop in developing countries after rice, wheat, and maize; these crops are important for food security ( Dash and Rai, 2016 ). The most destructive threat to banana production is Panama disease, caused by Foc .
It is extremely difficult to develop new banana varieties by conventional breeding methods, due to the sterility, polyploidy, and parthenocarpy of most banana cultivars ( Michael and Abdou, 2011 ). Genetic modification, which compensates for the lack of traditional breeding opportunities, is an effective way to develop bananas with improved agronomic traits, such as increased disease resistance and yield. Two major challenges face banana breeders aiming to produce genetically modified banana varieties with Foc resistance and no yield penalty.
Finally, once the molecular mechanisms are better understood, genetic engineering techniques, such as precise genome editing, can be used effectively to develop genetically engineered elite banana cultivars with improved disease resistance, ideal architecture, and increased production. Author Contributions XW, RY, and JL conceived, designed the work, and wrote the manuscript. All authors contributed to the article and approved the submitted version. Conflict of Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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