Volume 4 Special Issue 1 2010
Bananas, plantains and enset I

ISBN 978-4-903313-62-7

How to reference: Staver C, van den Bergh I, Karamura E, Blomme G, Lescot T(2010) Targeting Actions to Improve the Quality of Farmer Planting Material in Bananas and Plantains – Building a National Priority-setting Framework. In: Tripathi L (Ed) Bananas, plantains and enset I. Tree and Forestry Science and Biotechnology 4 (Special Issue 1), 1-10

Guest Editor

Leena Tripathi

International Institute of Tropical Agriculture (IITA), Uganda

www.iita.org

CONTENTS AND ABSTRACTS

Charles Staver, Inge van den Bergh (France), Eldad Karamura, Guy Blomme (Uganda), Thierry Lescot (France) Targeting Actions to Improve the Quality of Farmer Planting Material in Bananas and Plantains – Building a National Priority-setting Framework (pp 1-10)

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Invited Review: In recent decades the productivity of banana and plantain, traditionally important small farmer crops, has come under increasing threat from the spread of viruses and other phytosanitary problems transmitted in vegetative planting material. In addition, while for many other crops small farmers have improved access to new cultivars with increased yield potential and pest and disease resistance, for banana and plantain such access is as yet incipient. To harness the potential of banana and plantain as a small farmer crop, we propose that systems for cultivar deployment and the propagation of clean planting material need to be developed for the specific conditions of each country or region. A clonal crop “seed” system consists of all individuals, organizations and institutions which are linked to the genetic make-up, the quality and the supply of planting material. To develop guidelines for the identification of priorities for system strengthening, a survey was carried out in Asia, Africa and Latin America. National seed systems were profiled using a questionnaire designed to capture simple information about the quality and quantity of planting material and the extent of the formal mechanisms for deploying cultivars and multiplying planting material. Information from more than 30 countries was analyzed and scientific advances in pest and disease management and genetic improvement reviewed to generate a four-level decision tree (Musa diversity, importance of AAB types, presence of diseases such as banana bunchy top virus and the current formal seed system capacity). Based on an exercise to prioritize distinct and specific actions, 12 different groups of countries were identified with similar limiting factors, obstacles and opportunities for strengthening their system for cultivar deployment and planting material propagation.

Mathiyazhagan Kavino, Sankarasubramanian Harish (India/Taiwan R.O.C.), Duraisamy Saravanakumar, Prabhakaran Jeyakumar, Neelakandan Kumar, Ramasamy Samiyappan (India) Biological Hardening - A New Approach to Enhance Resistance against Biotic and Abiotic Stresses in Micropropagated Plants (pp 11-21)

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Invited Review: Micropropagated plantlets are physiologically different from normal plants showing reduced photosynthetic activity, lower wax deposits, poorly functioning stomata, under developed root system and very few leaf and root hairs. These problems can be significantly overcome by inoculating beneficial microorganisms into micropropagated plantlets. In addition, the beneficial microorganisms protect the micropropagated plantlets from varied biotic and abiotic stresses such as saline, drought and flooding. Recently biological hardening (biopriming) is associated with the induction of resistance in tissue culture propagules using beneficial microorganisms against biotic and abiotic stresses upon transplanting and during early growth after transplanting. Among the different beneficial microbes, use of plant growth promoting rhizobacteria (PGPR) in plant nurseries have advantage in accelerating the production process by minimizing the time required for lignification of micropropagated plantlets. Research findings from several laboratories demonstrated the bacteria mediated improvement in host physiology and their studies indicated the sustainability of microbes and their utilities in micropropagated plantlets especially for banana (Musa spp) even after transplanting into field conditions.

Justin N. Okolle (Cameroon/Malaysia), Abu Hassan Ahmad, Mashhor Mansor (Malaysia) Bioecology and Management of the Banana Skipper (Erionota thrax) (pp 22-31)

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Invited Review: Bananas and plantains are important food crops to several people in the world. One of the most important folivorous insect pest on these crops is the banana skipper; Erionota thrax. The larvae of these large butterflies can cause mean leaf defoliation of about 60%, leading to yield losses of about 20%. Indigenous to Southeast Asia, life stages of the pest are attacked by several parasitoids of which Ooencyrtus erionotae, Cotesia erionotae and Brachymeria spp. are the major ones. Infestation and parasitism of the pest varies with plant growth stages, leaf ages, between interior and field edges, and seasons. Significantly higher infestation and parasitism found on pre-flowered plants, younger leaves and during the rainy season. In addition, eggs and larvae are randomly distributed while pupae are clumped and parasitized eggs and pupae are clumped while that of larvae is random. Although E. thrax has never been reported on non-Musa species or weeds, other smaller Erionota species have been recorded on Asystacia intrusa, Ipomoea cairica, Mimosa pudica and Cloeme rutidesperma.

Kazumitsu Matsumoto, Damares de Castro Monte, João Batista Teixeira (Brazil), Robert Haїcour (France), Michael R. Davey (UK) Banana Protoplasts: Culture and its Applications (pp 32-38)

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Invited Mini-Review: Protoplast technology is an important adjunct to conventional plant breeding. The culture of banana protoplasts has advanced considerably in recent years through the use of embryogenic cell suspensions as a source of protoplasts, combined with nurse cultures. Protoplast transformation and somatic hybridization have also become feasible techniques to support the genetic improvement of banana. The present discussion reviews the advantages and disadvantages of the use of protoplasts compared with other methods of genetic transformation and conventional sexual hybridization. General protocols for protoplast culture, genetic transformation and somatic hybridization are presented.

Temesgen Addis, Ferdu Azerefegne, Tameru Alemu, Sisay Lemawork, Eyob Tadesse, Mesele Gemu (Ethiopia), Guy Blomme (Uganda) Biology, Geographical Distribution, Prevention and Control of the Enset Root Mealybug, Cataenococcus ensete (Homoptera: Pseudococcidae) in Ethiopia (pp 39-46)

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Invited Review: More than 15-million Ethiopians depend upon enset for their food, fibre, animal forage, construction materials and medicines. However, the sustainability of enset-based agriculture is threatened by a number of factors. The main biotic stresses are bacterial wilt, the enset root mealybug, nematodes, fungi and other vertebrate pests like mole-rats. Enset root mealybug, Cataenococcus ensete is a major pest of enset (Ensete ventricousm) in enset growing areas of southern Ethiopia. This paper reviews the recent body of work on integrated control measures for enset mealybug (Cataenococcus ensete). Its focus includes: biology and description of C. ensete; the pest’s behaviour within the enset plant; its geographical distribution; pest symptoms; mealybug dispersal methods and key means of mealybug management including prevention and cultural, biological and chemical control (including plant-extracts). The enset mealybug is difficult to control with insecticides, due to its cryptic nature, waxy-coat and life-style of forming dense colonies of multiple and overlapping generations. Besides, insecticides often prove too costly. This review should allow researchers and extension agents to make more informed choices regarding a more effective, integrated approach to control enset root mealybug.

Patrick K. Mobambo (Democratic Republic of Congo), Friedhelm Gauhl, Cornelia Pasberg-Gauhl (Austria), Rony Swennen (Beligium), Charles Staver (France) Factors Influencing the Development of Black Streak Disease and the Resulting Yield Loss in Plantain in the Humid Forests of West and Central Africa (pp 47-51)

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Invited Mini-Review: Plantain, an important staple food crop in the humid tropics, is threatened by black leaf streak (Mycosphaerella fijiensis Morelet), an airborne fungal leaf spot disease. Due to limitations associated with the use of chemicals in Africa, cultural practices are used to minimize the disease effect on crop yields. Research on breeding for resistance has been undertaken at the International Institute of Tropical Agriculture (IITA) and plantain hybrids have been produced. Studies on black leaf streak severity were conducted in Central Africa on plantain and in West Africa on both plantain and tetraploid hybrids of plantain to identify the factors involved in the disease development. These are the environmental and biological factors to which growth and yield performances of the crop are also related. Over cropping cycles, plantain is much affected by the complex of disease, pests and soil fertility decline which together can reduce yield by more than 90%, when calculated from the difference in yield between the plant crop (first cycle) of the fungicide-treated and the ratoon crop (second cycle) of the non-treated plantain. Thus, proper management of soil organic matter for the sustainable productivity of plantain is considered as the most feasible and realistic approach reducing the black leaf streak severity with low inputs and good fruit quality in Africa.

Olivia Saha Roy, Pranay Bantawa, Swapan Kumar Ghosh (India), Jaime A. Teixeira da Silva (Japan), Partha DebGhosh, Tapan Kumar Mondal (India) Micropropagation and Field Performance of ‘Malbhog’ (Musa paradisiaca, AAB group): A Popular Banana Cultivar with High Keeping Quality of North East India (pp 52-58)

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Original Research Paper: A method has been developed to multiply ‘Malbhog’ (Musa paradisiaca AAB group) in vitro and to transfer it to the field. It is a very popular banana cultivar in the North Eastern part of India. Meristematic tips were cultured on agar-solidified Murashige and Skoog (MS) medium supplemented with 3% sucrose and fortified with various cytokinins [6-benzyl aminopurine (1-7.5 mg/l), kinetin (1-7.5 mg/l), thidiazuron (TDZ) (0.05-0.44 mg/l)] alone, or in combination with an auxin [indole-3-acetic acid, α-naphthalene acetic acid or IBA (indole-3-butyric acid)], each at 0.5-2.0 mg/l to optimize the suitable concentrations of plant growth regulators. Among the combinations tested, MS + 0.11 mg/l TDZ produced the maximum number of shoots (45 shoots/explant) 8 weeks after inoculation. Subsequently, plantlets rooted in vitro with MS supplemented with 1 mg/l IBA (6 roots/explants) within 2 weeks, hardened in the greenhouse and transferred to the field with 95% survival, 5 months after inoculation. Even though micropropagated plants produced more leaves, grew faster and had more suckers than their vegetative counterparts, there was no significant variation in physio-chemical analyses and fruit morphology of the ripened fruits between the two plant types. Micropropagated plants were genetically uniform to donor plants, as indicated by random amplified polymorphic DNA analysis.

Korn Koarapatchaikul, Kamnoon Kanchanapoom (Thailand) Plant Regeneration from Callus Cultures of Diploid Bananas (Musa acuminata, AA Group) ‘Kluai Sa’ and ‘Kluai Leb Mu Nang’ and Analysis of Ploidy Stability Using Flow Cytometry (pp 59-63)

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Original Research Paper: Plant regeneration of diploid bananas (Musa acuminata, AA group) ‘Kluai Sa’ and ‘Kluai Leb Mu Nang’ was achieved through organogenesis in callus cultures. Calluses were induced from in vitro-grown shoot tips of both cultivars on a modified Murashige and Skoog medium containing 100 mg L^-1 malt extract, 50 mg L^-1 proline, 50 mg L^-1 cysteine, 100 mg L^-1 glutamine, 1 mg L^-1 biotin, 5-7 mg L^-1 dicamba and 1-2 mg L^-1 thidiazuron (TDZ). On these media, two morphologically distinct types of white and yellow compact calluses were produced. Green shoot buds were best induced after several transfers of the yellow compact calluses to MS medium supplemented with 1 mg L^-1 α-naphthalene acetic acid (NAA) and 3 mg L^-1 benzyladenine (BA) with 19 shoots in both cultivars. Rooting in all regenerated shoots was promoted on MS medium devoid of plant growth regulators but containing 0.2% activated charcoal. All the resultant plants were shown to be morphologically normal. Acclimatization and survival when transferred to field conditions were shown to be 100% in the regenerated plants. Flow cytometric analysis of nuclear DNA content confirmed that they were all diploid with a 2C peak indicating that ploidy alteration did not occur.

Savarimuthu Mukunthakumar, Govindh Praveen, Sooriamuthu Seeni (India) Rapid Propagation of Two Seedless Diploid (AB) Land Races of Musa through in Vitro Culture of Shoot and Inflorescence Apices (pp 64-68)

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Original Research Paper: In vitro propagation of two diploid landraces of Musa cv. ‘Poonkadali’ and ‘Rasakadali’ was achieved through organogenesis by culturing shoot primordia (~35 × 18 cm) and inflorescence apices (~15 × 10 cm) dissected out from healthy flowering plants. Murashige and Skoog (MS) medium fortified with 1.5 mg l^-1 6-benzyl amino purine (BAP) induced initiation of healthy shootlets from shoot primordial meristems of ‘Rasakadali’ whereas a combination of 2.5 mg l^-1 BAP and 0.5 mg l^-1 indole-3-acetic acid (IAA) is required for shoot induction from non-dominant inflorescence meristems of ‘Rasakadali’. In cultivar ‘Poonkadali’ 3.0 mg l^-1 BAP and 0.5 mg l^-1 IAA was obligatory for optimal shoot initiation from shoot apices while inflorescence apices responded maximum at concentrations of 4 mg l^-1 BAP and 1.5 mg l^-1 IAA. Transfer of shoots (4-5 cm) to MS basal medium containing 0.1% activated charcoal favored augmented growth of healthy shootlets and profusion of roots within 4 weeks. Multiple shoot proliferation was achieved through five subcultures of the isolated shoots without any decline. Enhanced multiplication rate achieved from floral meristems of these diploid cultivars can have unswerving impact in popularization of banana cultivation particularly in rural farmer lands.

Amin Retnoningsih, Rita Megia, Alex Hartana (Indonesia) Molecular Verification and Diversity Analysis of Indonesian BB, AAB and ABB Banana Cultivars (pp 69-76)

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Original Research Paper: Genetic diversity of bananas in Indonesia is considered to be high. Phenotypic identification of banana accessions is sometimes incorrect due to instability of morphological characters. The aims of this study were to verify Indonesian bananas accessions containing the B genome previously identified based on morphological characters, to construct a molecular determination key for the genomic groups, and to reveal genetic relationships among the accessions based on microsatellite markers. The DNA of 92 banana accessions classified as containing the B genome was analyzed using 8 pairs of microsatellite primers. The results showed that 9 accessions were incorrectly classified as containing the B genome. Of the remaining 83 accessions, 76 were accurately classified as AAB, ABB, or BB; and 7 accessions needed to be reassigned to a different subset of the B-genome containing accessions. Alleles MaCIR108 size longer than 270 bp were considered as the diagnostic characters for the B genome, while one allele Ma-3-90 size of 152 bp could be used to distinguish AAB from ABB genomic groups. The molecular determination key constructed classified the 83 accessions into 3 genomic groups, consisted of 8 accessions of BB, 33 accessions of AAB, and 42 accessions of ABB. Genetic relationship analyses of the 83 accessions based on the 8 primers detected only 67 genotypes due to the presence of 8 identical genotypes consisting of 24 accessions. The accessions clustered according to their genomic groups. ABB formed fewer clusters than the AAB genomic groups indicating less diversity in the ABB group.

Candice Mello Romero Santos, Claudia Fortes Ferreira, Lizangela Pinheiro Cassiano, Marly Catarina Felipe Coelho, Roberto Coiti Togawa, Natalia Florêncio Martins (Brazil), Manoel Teixeira Souza Júnior (The Netherlands) Transcriptome Analysis of Leaves and Roots of Musa balbisiana var. ‘Pisang Klutuk Wulung’ (pp 77-82)

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Original Research Paper: Banana and plantain (Musa spp.) are perennial herbs belonging to the Musaceae family. Almost the totality of cultivated banana genotypes originated from natural intra- and inter-specific hybridization of two diploid species; Musa acuminata Colla and Musa balbisiana Colla; representing the A and B genomes, respectively. This study reports the construction and characterization of two cDNA libraries from the M. balbisiana var. ‘Pisang Klutuk Wulung’ (BB), also known as PKW. Roots and leaves from PKW hydroponics plants were used to construct these two cDNA libraries. Sequencing of cDNA clones, followed by trimming and CAP3 assembling of high quality ESTs resulted in 2,967 MbAES (Musa balbisiana Assembled EST Sequences), with 435 contigs and 2,532 singletons. Approximately 38% of the MbAES came out as “no hits” after Blastx search against several public databases. Assembled EST sequences were classified into 23 different categories according to putative protein functions (KOG), whereas the range of similarity was from 35 to 60%. The classification of the EST clusters into the Gene Ontology (GO) function classes showed a predominance of catalytic activity and binding as molecular function. Among the most populated contigs there were genes related to pathogenicity response, stress response and photosynthesis. A differential digital display between M. acuminata data already stored at the DATAMusa and M. balbisiana assembled EST sequences revealed 10 unknown genes exclusive to the B genome and nine exclusive to the A genome with statistically significant difference.

Roberto C. Togawa, Candice Mello Romero Santos, Robert N. G. Miller (Brazil), Manoel Teixeira Souza Júnior (The Netherlands), Natália Florêncio Martins (Brazil) DATAMusa - a Database for Ortholog Genes from Musa (pp 83-87)

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Research Note: Plantains and bananas (Musa spp.) are staple foods for rural and urban consumers in the tropics and an important source of income, particularly for smallholders. Given current threats to global Musa production caused by such biotic stresses, considerable input is being made in Musa breeding programs and genomics. The Global Musa Genomics Consortium (GMGC) has encouraged collaboration and genomics information and resource sharing between member institutes, ultimately for the development of improved cultivars for smallholder farmers. There are currently in the order of thirty thousand ESTs across members of the Musa genus in Genbank, 3000 nucleotides and 7000 are genome survey sequence records. The present work describes the DataMusa databank in which over nine thousand sequences from both genomes A and B have been stored and analyzed. The present work presents the database organization for all expressed sequence tag data. Sequences from different cDNA libraries were used to construct the database. Contig and singleton datasets were analysed via an in-house pipeline consisting of translation and alignment via Blast against several databases (non-redundant GenBank, Swissprot, KOG, GO and MIPs). Manual curation was used to annotate consensus sequences using an e-value cut-off of e^-20 over a 40% coverage based upon data from at least three databases. The organization of DATAMusa enabled the identification of hundreds of new genes and provided information for further molecular studies, such as molecular marker development, promoter screening, gene expression profiling and molecular pathway analyses. All data is available at http://genoma.embrapa.br/musa/index.html, with access authorization granted by the DATAMusa management committee.

Victor Edward Mshani, Moses Kwapata, James Bokosi, Weston Mwase, Joyce Njoloma, Moses Maliro (Malawi) Growth and Multiplication Ability of Musa Species Using the Whole-Corm Technique (pp 88-92)

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Original Research Paper: A split-split-plot design experiment was carried out during the winter to specifically determine the most suitable developmental stage for corm extraction to optimize the multiplication rate, identify the most suitable substrate and also establish the multiplication rates of the banana genomes using the whole-corm technique. The genetic constitution of the banana cultivar has an effect on the performance of different genotypes as triploid cultivars “Kabuthu” (AAA) and “Ngwewo” (AAB) showed superiority in all the parameters. Overall, triploids were superior seconded by tetraploids and then lastly diploids. There was also an inverse relationship between the number of roots and the number of days to regeneration. Corms obtained from fruiting banana plants produced plantlets much faster and were superior in most aspects as compared to corms from suckers and followers. The type of substrate had no significant effect on the performance of the different banana genomes.

Godfrey Taulya, Piet van Asten, Kephas Nowakunda, Phoebe Kaddu-Mukasa (Uganda) Mineral Fertilizers Improve the Sensory Quality of East African Highland Bananas (Musa AAA-EA, cv. ‘Kisansa’) (pp 93-96)

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Original Research Paper: Some farmers in Uganda believe that fertilizers negatively affect the sensory attributes of cooking type bananas. This belief may hamper the adoption of fertilizers. To verify the validity of this belief, bunches (Musa AAA-EA, cv. ‘Kisansa’) from fertilized (i.e. N-P-K-Mg-Zn-S-B-Mo) and non-fertilized plots were harvested from on-station trials in central (Wakiso) and southwestern (Ntungamo) Uganda. Samples were anonymously tagged for preparation (boiled or steamed) and sensory evaluation by farmers from southwestern (n=33) and central Uganda (n=35). Data were analyzed in STATA using Tau-b rank test for proportions, median ranks and odds ratios. The frequency of evaluators ranking fertilized steamed bananas highly (i.e. ‘Best’ or ‘Second-best’) was significantly (P≤0.05) higher (60%) than for non-fertilized bananas (42%). The opposite was true for boiled bananas (fertilized, 43% vs. non-fertilized, 60%). Irrespective of site of cultivation and evaluators’ origin, gender or age, fertilizers significantly (P≤0.05) improved the appearance, odor, softness and acceptability of steamed bananas. For boiled bananas, attributes did not significantly differ between fertilizer treatments, except for appearance, which was significantly inferior (P≤0.05) for fertilized bananas. This study shows that the belief that fertilizers negatively affect the sensory attributes of cooking type bananas is generally incorrect. Only when boiled, fertilized bananas appeared less attractive than non-fertilized bananas. The dominant and traditional way of preparing cooking type bananas in Uganda is through steaming (i.e., matooke). We recommend the application of fertilizer, as it will not only positively affect yield, but also the sensory quality of cooking type bananas.