2. Formulation of research options

Photo Credit: A. Molina/Bioversity International

The second step of the priority assessment exercise comprised the description of research options and adaptable output. Groups of resource persons described the research options that were selected in the Kampala workshop and subsequently assessed through the economic surplus model and cost-benefit analysis.

Click the links to find out more about each constraint, how RTB research addresses the constraint, status of research, adaptable innovations, expected impacts and target regions and systems.

 

 

Constraint

Banana bunchy top disease (BBTD) is one of the most devastating diseases of banana and plantain particularly for smallholders (Dale 1987). BBTD, caused by the banana bunchy top virus (BBTV), produces erect, narrow, short brittle leaves with yellow borders and typical dark green streaks on leaves and pseudostems and stunted suckers. It results in very small or no bunches (i.e., complete yield loss). Infected mats eventually die, but often remain as a source of inoculum. The disease spreads through infected suckers and via the banana aphid (vector). BBTD is widespread in Asia. The first cases of BBTD in sub-Saharan Africa (SSA) were reported in 1958, with an increase in the rate of spread in the last decades. The disease is now found from southern Malawi and Burundi/Rwanda/eastern Democratic Republic of the Congo (DRC) all the way to Nigeria, Central African Republic (CAR), and Benin (Kumar et al. 2011). While laboratory techniques for virus detection and development of BBTV-free planting materials are well established, neither of these services nor commercial sources of BBTV-free planting material are available in rural areas of Asia and Africa.

(Potential) RTB research

Generation of alternative practices, models, decision tools, and technologies for use in different land-use systems:

 

  • Clean seed supply through tissue culture and/or macro-propagation
  • Community strategies for a banana-free period to eliminate banana aphids on-site and a buffer area free of bananas to reduce aphid re-invasion into a newly-planted field
  • Approaches for eliminating or reducing re-infection of virus-free banana gardens.

 

Status of research

The research will build on extensive knowledge and field experience generated in Asia and the incipient experience in SSA. The focus of new research will be to build a more robust understanding of BBTV, its vector, and the interaction both with host diversity and with farmer practice and the surrounding agricultural system. Pilot sites will also be set up to generate tools for building community capacity to recover from BBTD destruction and to mobilize containment when BBTD is first identified. This represents a major research initiative, since most BBTD recovery to date has focused on commercial monocrop plantations. The estimated completion time for the research is nine years with a research success rate of 90%.

Adoptable innovations

 

  • Diagnostic tools
  • Strategies for supplying clean planting materials
  • Integrated approaches to the recovery of BBTD-affected areas involving the creation of a banana-free period and adequate buffer, replanting strategies, and the management of reinfection

 

Expected impact

 
  • Increase/recovery of crop yield
  • Increase in production costs (seed, labor for harvest)
 

Target region/system

Focus is on AAA-Cavendish and other AAAs in Asia (Philippines, Taiwan, Vietnam, Sri Lanka) and on diverse smallholder perennial systems of AAA EAHB and plantain (AAB) in West and Central Africa (DRC, Republic of Congo-Brazzaville, Equatorial Guinea, Cameroon, CAR, Gabon, Benin, Nigeria); East Africa (Burundi, Rwanda); and Southern Africa (Malawi, Angola), although other minor cultivar groups in the same areas would also be affected

 

 

      BXW MANAGEMENT: CULTURAL PRACTICES AND LOW-COST DIAGNOSTIC KIT

      Constraint

      The rapid spread of banana Xanthomonas wilt (BXW), caused by Xanthomonas campestris pv. musacearum, endangers the livelihoods of millions of farmers in East and Central Africa who rely on banana as a source of food and cash (Tushemereirwe et al. 2004; Tripathi et al. 2009). It is mainly transmitted via contaminated farming tools, insects acting as vectors, and infected planting material. Unchecked, the disease can destroy entire banana plantations. The pathogen infects all cultivated banana varieties in Eastern and Central Africa (ECA), including East African Highland bananas (AAA-EAHB), plantains, Pisang Awak and exotic types. Overall economic losses in ECA have been estimated at over US $2 billion over the past decade in ECA, due to price increases, significantly reduced production, and revenue losses (Abele and Pillay 2007). In Central Uganda alone, yields declined by 80–100% between 2003 and 2008 due to infections of BXW in Pisang Awak, with corresponding income loss and higher prices of banana beer. In affected areas, banana production has declined by more than 50%. Effects on AAA-EAHB highland production in the Kivu provinces of eastern DRC have been catastrophic due to lack of institutional infrastructure and knowledge dissemination networks. The disease has reportedly spread farther toward the southern parts of South Kivu (Uvira and Fizi) and the Oriental province in DRC. BXW has spread across 15 of the 17 provinces in Burundi over a two-year period. Many farmers are still unfamiliar with disease symptoms and control options. In addition, the current control options are highly labor intensive, expensive, and time consuming, limiting adoption.

      (Potential) RTB research

      Evaluation and dissemination of genotypes escaping insect vector transmission; better understanding of host-pathogen interaction for more easily adoptable control packages; develop stakeholders’ platforms for delivery of clean planting materials; raising public awareness to enhance adoption.

      Status of research

      Research on improved cultural practices for management of BXW is ongoing, and the current effort started in the year 2003. Past experiences have shown that is it very important to develop cultural practices in a participatory manner to ensure the technology package is attractive for adoption (Blomme et al. 2014) and does not conflict with resource (time, tools, knowledge, capital) limitations common for smallholder farmers (see, e.g., Jogo et al. 2011, 2013). A technology package will be developed, tested, and ready for adoption in seven years, with an estimated research success of 90%.

      Adoptable innovations

       
      • Low-cost diagnostic kit
      • Improved cultural practices: eradication, timely bud removal, tool disinfection, short banana-free fallow, diseased stem removal
       

      Expected impact

       

      • Increase/recovery of crop yield
      • Increase in production costs
      • Avoidance/lower pace of BXW spread (local and regional)

       

      Target region/system

       
      • All cultivar groups; smallholder banana production systems in ECA in countries where the disease is currently present: Burundi, DRC, Ethiopia, Kenya, Rwanda, Tanzania, and Uganda
      • All cultivar groups; smallholder banana production systems in ECA in countries under direct BXW threat: Angola, Cameroon, CAR, DRC, Gabon, Malawi, Mozambique, South Sudan, and Zambia

      BXW MANAGEMENT: GM-RESISTANT VARIETIES

      Constraint

      The rapid spread of banana Xanthomonas wilt (BXW), caused by Xanthomonas campestris pv. musacearum, endangers the livelihoods of millions of farmers in East and Central Africa who rely on banana as a source of food and cash (Tushemereirwe et al. 2004; Tripathi et al. 2009). It is mainly transmitted via contaminated farming tools, insects acting as vectors, and infected planting material. Unchecked, the disease can destroy entire banana plantations. The pathogen infects all cultivated banana varieties in Eastern and Central Africa (ECA), including East African Highland bananas (AAA-EAHB), plantains, Pisang Awak and exotic types. Overall economic losses in ECA have been estimated at over US $2 billion over the past decade in ECA, due to price increases, significantly reduced production, and revenue losses (Abele and Pillay 2007). In Central Uganda alone, yields declined by 80–100% between 2003 and 2008 due to infections of BXW in Pisang Awak, with corresponding income loss and higher prices of banana beer. In affected areas, banana production has declined by more than 50%. Effects on AAA-EAHB highland production in the Kivu provinces of eastern DRC have been catastrophic due to lack of institutional infrastructure and knowledge dissemination networks. The disease has reportedly spread farther toward the southern parts of South Kivu (Uvira and Fizi) and the Oriental province in DRC. BXW has spread across 15 of the 17 provinces in Burundi over a two-year period. Many farmers are still unfamiliar with disease symptoms and control options. In addition, the current control options are highly labor intensive, expensive, and time consuming, limiting adoption.

      (Potential) RTB research

      Evaluation and dissemination of genotypes escaping insect vector transmission; better understanding of host-pathogen interaction for more easily adoptable control packages; develop stakeholders’ platforms for delivery of clean planting materials; raising public awareness to enhance adoption.

      Status of research

      Development of GM resistant banana is ongoing at several institutions. In 2005, a consortium led by IITA started a project to develop EAHB AAA and AAA banana varieties resistant to BXW. The work is now in its second phase, and resistant varieties will be ready for adoption in eight years (plan to release the resistant variety in 2020), with estimated research success of 90%.

      Adoptable innovations

      GM-resistant varieties of dessert cultivars and East African Highland bananas

      Expected impact

       

      • Increase/recovery of crop yield
      • Increase in production costs
      • Avoidance/lower pace of BXW spread (local and regional)

       

      Target region/system

       
      • Dessert cultivars and East African Highland bananas in ECA in countries where the disease is currently present: Burundi, DRC, Ethiopia, Kenya, Rwanda, Tanzania, and Uganda
      • Dessert cultivars and East African Highland bananas in ECA in countries that are under direct threat of the disease: Angola, Cameroon, CAR, Malawi, Mozambique, South Sudan, and Zambia
       

      Opportunity

      Smallholder farmers access (urban) markets with good prices and (growing) demand, especially for off-season production

      Constraint

      Banana yields realized by smallholder farmers are generally low and do not bring high revenues due to suboptimal timing of harvest for two main reasons: (1) farmers are not sufficiently aware and/or responsive to market prices, they have limited market access opportunities, and prices fluctuate largely (seasonality); and (2) farmers are not technically equipped (production system knowledge) or have insufficient resources to produce high yields (at the right time), including pest management practices such as clean and uniform planting material and BLS, improved plant nutrition, irrigation and soil health practices.

      (Potential) RTB research

      Develop an integrated crop intensification package adapted to the local biophysical and socioeconomic environment, including quality planting material, timing of production: sucker/planting (timing for high prices), select suitable varieties (fit for local market and agro-ecology), integrated soil fertility management (ISFM), integrated pest management (IPM), plant densities, irrigation/water management, improved intercrop systems, and postharvest management.

      Status of research

      Ongoing, but new research started in year 2013; technology ready for adoption in five years (2018), with research success of 90%.

      Adoptable innovations

       

      • Diagnostic survey tools and models to identify key constraints/entry points to improve yields
      • Recommendations for improved productivity technologies adapted to different degrees of market access, natural resource quality and farm household resources
      • Communication/training tools—for example, technical sheets, short videos to reach end-users through training of trainers, (innovative and effective) farmer organizations

       

      Expected impact

       

      • Increased crop yield
      • Increase in production costs (irrigation, fertilizer, planting material)
      • Reduced yield variability (at this stage not included in the assessment)
      • Positive effect on natural resources (e.g., soil) (at this stage not included in the assessment)

       

      Target region/system

      Smallholder systems of EAHB in Eastern Africa; AAB plantain in WCA and LAC; Cavendish and other AAA dessert bananas in Asia (excluding major export areas with intensive production); Asia: Bangladesh, Indonesia, Myanmar, Papua New Guinea (PNG), Philippines, Sri Lanka, Vietnam; Africa: Burundi, Cameroon, Cote d’Ivoire, DRC, Ghana, Guinea, Nigeria, Rwanda, Tanzania, Uganda; LAC: Cuba, Dominican Republic, Haiti, Honduras, Nicaragua, Peru

      Constraint

      Infestation with nematodes, weevils, black leaf streak (BLS, Sigatoka), and Fusarium result in substantial yield and postharvest losses in banana production in LAC, Africa, and Asia.

      (Potential) RTB research

      Mitigating losses from the mentioned pests/diseases (namely BLS, nematodes, weevils, and Fusarium) through breeding for (improved) disease resistance and high-quality fruit; research on pathogen population structures.

      Status of research

      Banana breeding has been ongoing at IITA and CARBAP (African Centre for Research on Banana and Plantains), first- and second-generation hybrids with improved disease resistance are available (see, e.g., Lemchi et al. 2005), but room for improvement (distinguish release of existing improved material and new breeding efforts in the assessment). Release of existing material would take some 7 years (some issues with built-in virus), new breeding would result in improved varieties in 17 years, with research success of 100%.

      Adoptable innovations

       

      • East African Highland banana varieties (AAA) resistant to nematodes, weevils, and BLS
      • Plantain-like varieties (AAB) resistant to BLS, nematodes, and weevils, and with improved quality traits
      • Sweet acid banana varieties (other AAB and ABB) resistant to FW (Fusarium oxysporum f. sp. Cubense), BLS, and nematodes, and with improved quality traits. Assessment still ongoing (has not been completed)

       

      Expected impact

       

      • Yield recovery where disease has already reduced yields (yield increase)
      • Reduction of postharvest losses due to reduced stress of the plant
      • Increase in production costs due to higher seed costs

       

      Target region/system

       

      • Mixed AAA EAHB cropping systems of smallholders in East Africa: Burundi, DRC, Rwanda, Tanzania, and Uganda
      • Mixed AAB plantain cropping systems of smallholders in Asia: India; Africa: Cameroon, Congo, Cote d’Ivoire, DRC, Gabon, Ghana, Liberia, Nigeria; LAC: Brazil, Colombia, Costa Rica, Ecuador, Honduras, Mexico, Nicaragua, Panama, and Venezuela
      • Monoculture and mixed systems of sweet acid banana in Asia: India, Indonesia; Africa: Burundi, Cameroon, Ghana, Rwanda, Tanzania, Uganda; LAC: Brazil, Colombia, Mexico, Peru, Venezuela (not assessed at this stage)

       

       

      FUSARIUM RESEARCH OPTION A: IMPROVED QUARANTINE AND SURVEILLANCE MEASURES TO AVOID SPREAD OF FUSARIUM TR4

      Constraint

      Global banana production is seriously threatened by the re-emergence of Fusarium Wilt (FW). The LAC region experienced one of the most devastating plant disease epidemics in history. Starting in the 1920s and culminating in the 1950s, FW of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), wiped out large production areas of Gros Michel, the initial export banana from LAC. Foc is particularly devastating, because it remains in the soil for decades. The race of Foc affecting Gros Michel became known as Race 1 (R1) and also affects other cultivars such as Pisang Awak, Apple, Prata, and Isla. Race 2 (R2) has also been identified that affects certain ABB Bluggoe-type cooking bananas. The industry circumvented the problem by a shift to R1-resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new highly virulent strain of Foc (tropical race 4-TR4) is now affecting Cavendish plantations in Asia, the Middle East and Africa, threatening the banana industry globally. TR4 also threatens millions of smallholders worldwide because, unlike R1 and R2, it affects most banana cultivars used and based on current shares of cultivars affects 80% of all banana production area (Ploetz 2009, OIRSA meeting). In Australasia an estimated 100,000 ha of commercial banana plantations have been devastated by TR4. As the pathogen persists in the soil for many decades, susceptible varieties cannot effectively be planted ever again. Preventing the entrance and further spread of TR4 is the first strategy. Therefore, research actions aiming pathogen exclusion and strengthening quarantine and surveillance measures are necessary. Also included here are measures to eradicate the first plants detected and contain the spread of the disease.

      (Potential) RTB research

      RTB research would comprise the following interventions:

       

      • Strengthen science-based risk analysis protocol for Foc movement for local, national, regional and intercontinental use
      • Validate efficient surveillance protocols to detect, delimitate and monitor Foc spreading
      • Understand risk and pathways of Foc dissemination in soil, suckers, humans, other banana parts, diverse agricultural and non-agricultural practices within country, across borders and between continents
      • Determine the effectiveness of different eradication and isolation procedures for first detected Foc affected banana plants in Foc-free areas
      • Develop/improve protocol to produce Foc-free planting material from TC, suckers and macropropagation
      • Develop models for Foc epidemiology & pathogenicity and more efficient tools for epidemiological studies
      • Determine the population structure of the pathogen, cultivar-specific disease intensity and distribution of Foc populations currently present in major banana producing countries
      • Develop and optimize diagnostic protocols for TR4 and other relevant Foc strains
      • Evaluate susceptibility/resistance of major cultivars and parental lines used in breeding programs to Foc TR4 and other relevant Foc strains
       

      Status of research

      Research initiatives focusing quarantine and surveillance are limited. There are advances in the production of Foc-free planting material through tissue cultures, but protocols need to be improved to increase the adoption levels. A diagnostic protocol is available for TR4, but not for other Foc strains. Recent concerns about specificity of the TR4 diagnostic for in planta detection have emerged, indicating the need of further improvements. Development of improved quarantine and surveillance measures would take 5 years with an estimated probability of research success of 80%.

      Adoptable innovations

      (Improved) exclusion, surveillance, containment and early eradication measures on farm, community, national and international level

      Expected impact

       

      • Yield loss avoided through containment
      • Slower and/or reduced spread of disease
      • Increase in (production) cost
       

      Target region/system

       
      • Production areas of all six cultivar groups (Cavendish AAA; other AAA + Gros Michel + AA; East African Highland AAA; AAB Plantain; other AAB; ABB) in countries in Africa, LAC and Asia where Fusarium is either already present or will very likely spread in the near future
      • Africa: Burundi, Cameroon, Congo, D.R., Côte d'Ivoire, Ghana, Kenya, Mozambique, Nigeria, Rwanda, Tanzania, Uganda; Asia/Pacific: China, India, Indonesia, Malaysia, Myanmar, Pakistan, Papua New Guinea, Philippines, Thailand, Vietnam; LAC: Brazil, Columbia, Costa Rica, Ecuador, Guatemala, Mexico, Nicaragua, Peru
       


      FUSARIUM RESEARCH OPTION B: INTEGRATED CROP AND DISEASE MANAGEMENT TO REDUCE THE IMPACT OF FUSARIUM R1, R2, STR4, TR4

      Constraint

      Global banana production is seriously threatened by the re-emergence of Fusarium Wilt (FW). The LAC region experienced one of the most devastating plant disease epidemics in history. Starting in the 1920s and culminating in the 1950s, FW of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), wiped out large production areas of Gros Michel, the initial export banana from LAC. Foc is particularly devastating, because it remains in the soil for decades. The race of Foc affecting Gros Michel became known as Race 1 (R1) and also affects other cultivars such as Apple, Prata, and Isla. Race 2 (R2) has also been identified that affects certain ABB cooking bananas. The industry circumvented the problem by a shift to R1-resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new highly virulent strain of Foc (tropical race 4-TR4) is now affecting Cavendish plantations in Asia and Africa, threatening the banana industry globally. TR4 also threatens millions of smallholders worldwide because, unlike R1 and R2, it affects most banana cultivars used and based on current shares of cultivars affects 80% of all banana production area (Ploetz 2009, OIRSA meeting). In Australasia an estimated 100,000 ha of commercial banana plantations have been devastated by TR4. As the pathogen persists in the soil for many decades, susceptible varieties cannot effectively be planted ever again. While preventing the spread of TR4 should be the first strategy, disease management must be strengthened in parallel. There has been some success with cultural practices to manage Fusarium (in Asia and for R1 in LAC), but long-term research aiming to reduce pathogen inoculum, create suppressive and healthy soils and boosting plant defences are necessary.

      (Potential) RTB research

      Recent research proves that FW can be managed in small plots within acceptable control levels through soil and crop management. However, a better understanding of both disease epidemiology and host-soil-pathogen relationships is necessary in order to generate science-based and scalable management strategies. RTB research would comprise the following interventions: 

      • Strengthen science-based risk analysis protocol for Foc movement for local, national, regional and intercontinental use
      • Develop/improve protocol to produce Foc-free planting material from TC, suckers and macro propagation
      • Develop model for Foc epidemiology & pathogenicity + more efficient tools for epidemiological studies
      • Determine the population structure of the pathogen, cultivar-specific disease intensity and distribution of Foc populations currently present in major banana producing countries
      • Develop and optimize diagnostic protocols for TR4 and other Foc races
      • Evaluate susceptibility/resistance of major cultivars to Foc TR 4 and other races
      • Identify and evaluate cover crops, intercrops and other agronomic and soil management practices that suppress or accelerate Foc in banana and clarify mechanisms involved
      • Understanding functional diversity of suppressive vs. conducive soils in banana production contrasting biological, physical, chemical properties
      • Screen + characterize root-associated microorganisms w/ Foc suppressive & growth promotion capacity
      • Prototype integrated Foc management strategies based on biological inputs (including microorganisms),  crop (including resistant genotypes and chemical fertilizers fine tuning) and cropping (including) systems
       

      Status of research

      A complete crop and disease management package will be developed, tested, and ready for adoption in ten years (partial results will be used by farmers in 5 years), with an estimated probability of research success of 90%.

      Adoptable innovations

      -   Crop and disease management package

      Expected impact

       
      • Reduced yield loss (avoided losses) when Fusarium is present
      • Increase in labour/input cost
       

      Target region/system

      • Production area of all six cultivar group (Cavendish AAA; other AAA + Gros Michel + AA; East African Highland AAA; AAB Plantain; other AAB; ABB) in LAC and Asia (integrated management of TR4)
      • ‘Cavendish AAA’ production areas in Africa (integrated management of TR4)
      • ‘Other AAA’ and ‘other AAB’ in LAC and Asia (integrated management of Race 1)
      • We do not consider Race 2 in the assessment of this research option since it is not very likely that the research output would be used for planting ABB. The reason therefore is that ABB is a cultivar susceptible to Race 2 which has not been intensified almost anywhere it has been grown.
      • Africa: Cameroon, Côte d'Ivoire, Ghana; Asia/Pacific: China, India, Indonesia, Malaysia, Myanmar, Pakistan, Philippines, Thailand, Vietnam; LAC: Brazil, Columbia, Costa Rica, Ecuador, Guatemala, Mexico, Nicaragua, Peru
       

      FUSARIUM RESEARCH OPTION C: DEVELOPMENT OF FUSARIUM RESISTANT BANANA CULTIVARS

      Constraint

      Global banana production is seriously threatened by the re-emergence of Fusarium Wilt (FW). The LAC region experienced one of the most devastating plant disease epidemics in history. Starting in the 1920s and culminating in the 1950s, FW of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), wiped out large production areas of Gros Michel, the initial export banana from LAC. Foc is particularly devastating, because it remains in the soil for decades. The race of Foc affecting Gros Michel became known as Race 1 (R1) and also affects other cultivars such as Apple, Prata, and Isla. Race 2 (R2) has also been identified that affects certain ABB cooking bananas. The industry circumvented the problem by a shift to R1-resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new highly virulent strain of Foc (tropical race 4-TR4) is now affecting Cavendish plantations in Asia and Africa, threatening the banana industry globally. TR4 also threatens millions of smallholders worldwide because, unlike R1 and R2, it affects most banana cultivars used and based on current shares of cultivars affects 80% of all banana production area (Ploetz 2009, OIRSA meeting). In Australasia an estimated 100,000 ha of commercial banana plantations have been devastated by TR4. As the pathogen persists in the soil for many decades, susceptible varieties cannot effectively be planted ever again. While preventing the spread of TR4 should be the first strategy, disease management must be strengthened in parallel. Currently, no cultivars resistant to TR4 are available, but opportunities exist by exploring germsplasm banks, wild type species already identified with high levels of resistance and somaclonal variation.

      (Potential) RTB research

      RTB research would comprise the following interventions:

       

      • Prospection for new sources of resistance to Foc in germplasm collection, including breeding lines
      • Identify and characterize resistance genes (and molecular markers) to support breeding processes including Marker Assisted Selection
      • Generate diploid pre-breeding lines for major groups resistant Foc with emphasis on TR4
      • Develop efficient protocols for phenotyping of breeding lines
      • Develop conventionally bred bananas with Foc resistance
      • Strengthen protocols and develop somaclonal & clonal selection for Foc resistance in susceptible cultivars
      • Identify possible Foc resistant substitutes for the major susceptible market and food security cultivars and select for clones with superior traits
      • Evaluate and select resistant genotypes on multi-site field experiments
      • Evaluate and develop post-harvest and market oriented strategies

       

      Status of research

      Some clonal variants with quantitative resistance have been identified and currently explored in Asia. However, a remarkable genotype - environment interactions have been also reported. Wild species with full resistance have been identified, but these genes need to be transferred to commercial cultivars. Resistant cultivars would be available in 15 years, with an estimated probability of research success of 60%.

      Adoptable innovations

      High yielding and market accepted Fusarium resistant varieties

      Expected impact

       

      • High yield despite Fusarium presence (avoided losses)
      • Increase in seed costs
      • Lower price
      • Not meeting consumer preferences

       

      Target region/system

       
      • Production area of all six cultivar group (Cavendish AAA; other AAA + Gros Michel + AA; East African Highland AAA; AAB Plantain; other AAB; ABB) in Africa, LAC and Asia
      • Africa: Burundi, Cameroon, Congo, D.R., Côte d'Ivoire, Ghana, Kenya, Mozambique, Nigeria, Rwanda, Tanzania, Uganda; Asia/Pacific: China, India, Indonesia, Malaysia, Myanmar, Pakistan, Philippines, Thailand, Vietnam; LAC: Brazil, Columbia, Costa Rica, Ecuador, Guatemala, Mexico, Nicaragua, Peru
       

      FUSARIUM RESEARCH OPTION D: DEVELOPMENT OF GMO FUSARIUM RESISTANT BANANA CULTIVARS

      Constraint

      Global banana production is seriously threatened by the re-emergence of Fusarium Wilt (FW). The LAC region experienced one of the most devastating plant disease epidemics in history. Starting in the 1920s and culminating in the 1950s, FW of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), wiped out large production areas of Gros Michel, the initial export banana from LAC. Foc is particularly devastating, because it remains in the soil for decades. The race of Foc affecting Gros Michel became known as Race 1 (R1) and also affects other cultivars such as Apple, Prata, and Isla. Race 2 (R2) has also been identified that affects certain ABB cooking bananas. The industry circumvented the problem by a shift to R1-resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new highly virulent strain of Foc (tropical race 4-TR4) is now affecting Cavendish plantations in Asia and Africa, threatening the banana industry globally. TR4 also threatens millions of smallholders worldwide because, unlike R1 and R2, it affects most banana cultivars used and based on current shares of cultivars affects 80% of all banana production area (Ploetz 2009, OIRSA meeting). In Australasia an estimated 100,000 ha of commercial banana plantations have been devastated by TR4. As the pathogen persists in the soil for many decades, susceptible varieties cannot effectively be planted ever again. Currently no cultivars resistant to TR4 are available. While conventional breeding offers opportunities and need to be explored, technologies that speed up the development of resistant commercial varieties, such trans/ cis-genic and gene editing must be researched in parallel.

      (Potential) RTB research

      RTB research would comprise the following interventions:

       

      • Identify pathogenicity factors and defence / resistance genes and develop cisgenic and/or transgenic constructs to generate Foc resistant bananas
      • Develop GM bananas for Foc resistance
      • Phenotype GM bananas lines for Foc resistance at greenhouse level
      • Evaluate and select commercial GM lines resistant to Foc on multi-site field experiments
      • Evaluate and develop post-harvest and market oriented strategies

       

      Status of research

      Technologies to introduce genes in commercial varieties are already available, but the number of candidate genes is still low. In addition, a better understanding of basic principles of plant-pathogen interaction is needed to guarantee broad spectrum and durable resistance. GMO Fusarium resistant cultivars will be ready for adoption in 10 years, with an estimated probability of research success of 40%.

      Adoptable innovations

      High yielding and market-accepted genetically modified Fusarium resistant varieties

      Expected impact

       

      • High yield despite Fusarium presence (avoided losses)
      • Increase in seed costs
      • Lower price
      • Not meeting consumer preferences

       

      Target region/system

       
      • Production area of ‘Cavendish AAA’ in countries where local markets for this cultivar are important. This We assume that countries with export-oriented production patterns wouldn’t adopt GMO varieties due to political and consumer concerns in importing countries whereas countries with strong local markets for ‘AAA Cavendish’ would be more likely to adopt GMO varieties.
      • Africa: Burundi, Congo, D.R., Kenya, Mozambique, Nigeria, Rwanda, Tanzania, Uganda; Asia/Pacific: China, India, Indonesia, Malaysia, Myanmar, Pakistan, Thailand, Vietnam; LAC: Brazil, Mexico, Peru