Strategies for resistance to bacterial wilt disease of bananas through genetic engineering

The livelihoods of millions of Ugandan farmers have been threatened by current outbreak of a banana bacterial wilt disease caused by Xanthomonas campestris pv. musacearum, which is very destructive and rapidly spreading in Uganda. Bananas are the highest value staple food and source of income for millions of people in this region. Economic impact of the disease is clear as a result of widespread destruction of banana, pre-harvest rotting of fruits, and a lack of farmers' ability to grow bananas in disease endemic areas. The disease attacks all varieties of banana, including East African Highland Bananas (EAHBs). No banana germplasm with bacterial wilt resistance has been identified. The transgenic approach shows potential for the genetic improvement of the crop using a wide set of transgenes currently available which may confer bacterial resistance. This article discusses the potential strategies to develop transgenic banana plants resistant to bacterial wilt disease. Key Words: Banana, bacterial wilt, genetic transformation, disease resistant. African Journal of Biotechnology Vol.3(12) 2004: 688-69

Progress in understanding Pseudocercospora banana pathogens and the development of resistant Musa germplasm

Article purchased; Published online: 9 Feb 2018Banana and plantain (Musa spp.) are important food crops in tropical and subtropical regions of the world where they generate millions of dollars annually to both subsistence farmers and exporters. Since 1902, Pseudocercospora banana pathogens, Pseudocercospora fijiensis, P. musae and P. eumusae, have emerged as major production constraints to banana and plantain. Despite concerted efforts to counter these pathogens, they have continued to negatively impact banana yield. In this review, the economic importance, distribution and the interactions between Pseudocercospora banana pathogens and Musa species are discussed. Interactions are further scrutinized in the light of an emerging climate change scenario and efforts towards the development of resistant banana germplasm are discussed. Finally, some of the opportunities and gaps in knowledge that could be exploited to further understanding of this ubiquitous pathosystem are highlighted

Foliar Diseases of Banana in Uganda: Results from a Diagnostic Survey

Data are presented on the incidence and severity of (black and yellow) sigatoka leaf spots and Cladosporium freckle in different ecological zones of Uganda. Black sigatoka has become widespread since its arrival in Uganda in 1988. Sigatoka leaf spots were most severe in mid-elevation zones of central Uganda. The disease was absent at altitudes above 1500m and in drier zones (3-5 wet months per year). Cladosporium freckle was present at all survey sites and also most severe in central Uganda.Keywords: Banana, Cladosporium frekle, Sigatoka leaf spots, Ugand

Agroecological distribution of banana systems in the Great Lakes Region

Banana (Musa spp.) is important in the Great Lakes region of Africa as a staple food crop and source of income for the rural poor who also use it for various purposes; medicinal, cultural as well as industrial. The crop is grown across diverse agroecological conditions ranging from lowlands at sea level to highlands above 1500 m.a.s.l. Equally diverse are the socio-economic conditions associated with the crop across the region. The region is dominated both in production and acreage by the East African Highland bananas. Plantain and Cavendish production on the other hand dominate at the lower altitudes where the acreage under banana cultivation is steadily increasing. The agroecological diversity and the effects of socio-economic factors may have far-reaching implications to strategic planning for increased productivity of bananas especially considering possible effects on food security, pest/disease control, cultivar diversity and market/income. Using secondary information including existing databases on climate, land use/cover and edaphic factors, principal banana production areas have been mapped and an attempt made to overlay these with selected bio-physical and socio-economic factors in order to elucidate basic agroecological characteristics of these areas. The outcome clearly indicates that there exists potential for attaining food security and stable income, given the better climatic conditions prevailing, existing germplasm banks and near favourable accessibility. Opportunities and constraints based on climate, edaphic, human population densities and accessibility are recommended for further research and developments. KEY WORDS: Food security, geographic information systems (GIS), Musa spp., socio-economic factors RESUME La banane (Musa spp.) est importante dans la région des grands lacs comme nourriture de base et source des revenues pour les populations pauvres qui l'utilisent également pour d'autres buts, médical, culturel, et aussi bien qu'industriel. La plante est cultivée à travers diverses conditions agro écologiques des plaines aux hautes terres à 1500 m au dessus du niveau de la mer. Egalement diverses sont les conditions socio-économiques associées avec la plante à la région. La région est dominée en production et superficie par les bananes des hautes terres de l'Afrique de l'Est. La production de plantains et de Cavendish d'autre part est dominante dans les basses altitudes ou la superficie sous la banane est constamment croissante. La diversité agro écologique et les effets liés aux facteurs socio-économiques pourraient avoir entamé les stratégies de planification pour améliorer la productivité de la banane avec des effets sur la sécurité alimentaire, le contrôle de pestes/maladies, la diversité des variétés et le marché/revenu. L'utilisation des données secondaires, la base des données climatiques existante, l'utilisation des terres/ couverture végétale et les facteurs locaux, les zones de productions de la banana ont été identifiées et ont été super imposées sur les facteurs biophysiques et socio-économiques afin d'élucider les caractéristiques agro écologiques de base de ces zones. Le résultat indique clairement qu'il existe un potentiel pour atteindre la sécurité alimentaire et un revenu stable, étant donné l'existence des bonnes conditions climatiques, l'existence d'une banque de protoplasmes des germes et une bonne accessibilité. Les opportunités et les contraintes basées sur le climat, les conditions locales, la densité de la population humaine et l'accessibilité sont recommandées pour des recherches plus détaillées. Mots Clés: Sécurité alimentaire, système d'information géographique, Musa spp., facteurs socio-économiques African Crop Science Journal Vol.12(1) 2004: 33-4

Rapid and efficient production of transgenic East African Highland Banana (Musa spp.) using intercalary meristematic tissues

East Africa is the largest banana producing and consuming region in Africa. In particular, the East African Highland Banana serves as the major staple crop of countries like Uganda, but production isconstrained by a number of serious pests and diseases. Banana breeding is a very difficult and slow process, so genetic engineering offers an alternative approach to improvement. A transformationsystem using intercalary meristematic tissues was developed using Agrobacterium strain EHA105 harboring the binary vector pCAMBIA2301 containing the gusA reporter gene and nptII as selectable marker. In this paper, a new transformation protocol is described that yields kanamycin-resistant, GUSexpressingbanana plants from roughly 10% of the initial explants. The resulting fully-rooted transgenic plants do not appear to be chimeras since they can be stably propagated, GUS activity is observeduniformly throughout the plants including the germline cells of the meristem, and PCR and Southern blots indicate stable integration of the genes into the genome

Fusarium wilt resistant bananas considered appropriate replacements for cultivars susceptible to the disease in Uganda

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Development of a semi-selective medium for Xanthomonas campestris pv. musacearum

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Diseases threatening banana biodiversity in Uganda

Banana (Musa spp.) is the most important food crop in Uganda as indicated by consumption rate, annual production (9.5 M t ha-1) and agricultural land committed to the crop. This level of productivity (6.3 t ha-1 yr-1) is extremely low when compared to the yields obtained on station and well-managed plantations (60 t ha-1 yr-1). Previous diagnostic studies attributed the low productivity to diseases, pests, soil fertility decline, limited post harvest utilisation options and socioe-conomic problems. The susceptibility to pests and diseases is largely attributed to a low genetic base of banana in Uganda. Recent on station and on-farm studies suggest the major diseases threatening banana biodiversity in Uganda include: 1)Black sigatoka which severely affects all East African Highland (EA-AAA) banana cultivars and a range of introduced genotypes; 2) Fusarium wilt which affects several introduced genotypes though all EA - AAA bananas are resistant; 3) Banana streak virus causing different levels of infection on all types of banana cultivars; and 4) Banana bacterial wilt, a recent outbreak affecting all types of banana in Mukono and Kayunga districts (central Uganda). This paper illustrates the potential threat posed by the above diseases to Musa biodiversity in Uganda and highlights some of the recent studies undertaken to control the diseases. Key Words: Genetic base, Musa spp., production constraints RESUME La banane (Musa spp.) est la nourriture la plus importante en Ouganda comme indiqué par le taux de consommation, la production annuelle (9.5 M t ha-1) est la terre cultivée assignée à la plante. Ce niveau de productivité (6.3 t ha-1 an-1) est extrêmement faible quand on le compare aux rendements obtenus sur stations et des plantations bien aménagées (60 t ha-11 an-1). Des études antérieures ont attribué la faible productivité à des maladies, pestes, la diminution de la fertilité du sol, des options limitées d'utilisation lors de la récolte et des contraintes socio-économiques. La susceptibilité aux pestes et maladies est largement attribuée à une faible base génétique de la banane en Ouganda. Des études récentes sur station et sur terrain suggèrent que les maladies majeures menaçant la diversité de la banane incluent: 1) black sigatoka qui affecte sévèrement toutes les variétés de bananas des hautes terres de l'Afrique de l'Est (EA-AAA) et une gamme des génotypes introduits. 2) le Fusarium qui affecte plusieurs génotypes introduits malgré le fait que toutes les EA-AAA sont résistantes; 3) le virus de raie de la banane causant différents niveaux d'infection sur toutes les variétés de la banane, et 4) le champignon de la banane, une nouvelle éruption affectant toutes les variétés de la banane dans les districts de Mukono et Kayunga (au centre de l'Ouganda). Cet article illustre la menace potentielle posée par les maladies ci hautes citées de la diversité de la banane et fait mention des études récentes entreprises pour contrôler ces maladies. Mots Clés: Base génétique, Musa spp., contrainte à la production African Crop Science Journal Vol.12(1) 2004: 19-2

Reaction of banana germplasm to inoculation with Xanthomonas campestris pv musacearum

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Farmer evaluation of dried banana based products

A farmer participatory evaluation of dried banana based products was conducted in various districts of Uganda. Bananas were dried using a tunnel solar dryer developed by Post Harvest Handling and Storage project (PHHS) of Kawanda Post-harvest Programme and improved by the National Banana Research Programme. The dried banana was milled into flour using a high speed rotary mill. Porridge and thick-porridge (ugali) were prepared using 100% banana flour, a mixture of banana-millet flour in the ratios of 8:2 and 9:1, and banana-millet-soybean in the ratio 7:2:1, banana-millet-soybean- maize in the ratio of 7:1:1:1 and banana-millet-cassava in the ratio of 7:2:1. Acceptability of the products was tested by farmers and scored on a hedonic scale. Statistical analysis showed the mixture of banana-millet-soy in ratio of 7:2:1 and that of banana-millet in a ratio of 8:2 were best for porridge and thick porridge (ugali), respectively. Key Words: Acceptability, farmer participatory, hedonic scale, Musa spp. RESUME Une évaluation participative des fermiers des produits secs dérivés de la banane était conduite dans plusieurs districts de l'Ouganda. Les banana étaient séchées en utilisant un séchoir solaire en forme de tunnel développé par le projet Post Harvest Handling and Storage (PHHS) de Kawanda Post-Harvest Programme et amélioré par le National Banana Programme. Les bananes séchées étaient transformées en poudre en utilisant un moulin du type rotary à grande vitesse. La bouillie et le foufou étaient préparés sur base de la banane (100%), du mélange banane et millet a un taux de 8:2 et 9:1, et banane-millet-soya à un taux de 7:2:1, banane-millet-soya-maïs a un taux de 7:2:1. L'acceptabilité des produits était testée par les fermiers et marquée sur une échelle hédonique. L'analyse statistique montre que le mélange banane-millet-soya au taux de 7:2:1 et celui de la banane-millet au taux de 8:2 étaient les meilleurs pour la bouillie et l'ugali, respectivement. Mots Clés: Acceptabilité, participation des fermiers, echelle hédonique, Musa spp. African Crop Science Journal Vol.12(1) 2004: 27-3