In-vitro proliferation of Musa balbisiana improves with increased vitamin concentration and dark culturing

Musa balbisiana is a wild banana genotype with important traits such as drought tolerance and disease resistance. Uniform and clean plants are often required to study these traits in different laboratories but plants can only be generated through a tissue culture process yet for a long time a protocol for regeneration of the same has not been available. Here, we demonstrate that modification of the anti-oxidant content of the in- vitro plant proliferation medium through adjusting the concentration of ascorbic acid and thiamine HCl in the basal MS medium together with subjecting the explants to dark culturing conditions improved proliferation of M. balbsiana by over 10 fold. These treatments resulted in 40 shoots per initial explant material at the best performance

Postflask management of micropropagated bananas and plantains: A manual on how to handle tissue-cultured banana and plantain plants

Micropropagation techniques have the potential to deliver large amounts of propagules of vegetatively propagated plantain and banana, enabling the rapid dissemination of land races and new varieties resulting from breeding programs. However, a critical stage in the realization of this potential is postflask management, in order to rear the in vitro plantlets to a stage where field establishment is assured. This manual provides a stage-by-stage practical guide to postflask management beginning at the first stage of removal from the tissue culture facility through to the final stage of field establishment. The authors have drawn largely upon their own practical experience of this process, working in both lowland and mid-altitude humid environments. It is intended that this manual will be used by the technicians who are practically involved in the dissemination of plantain and banana germplasm

Ploidy level of the banana (Musa spp.) accessions at the germplasm collection centre for the East and Central Africa

Banana germplasm collections serves as a source of useful genes for banana breeding. However, insufficient and/or inaccurate information on the ploidy level of the germplasm renders its utilization in breeding difficult. The objective of this study was to determine and validate the ploidy level of 120 banana accessions in the ex situ germplasm collection centre for the East and Central Africa, located in Mbarara, Uganda. Flow cytometric analysis of the nuclear DNA content was used to determine the ploidy level of the accessions. Results indicate that accessions: Bura, Diana, Kambani-Rungwe, Paji and Pagatau, and Rungwe that were previously classified as diploids are actually triploids, whereas Selangor previously known to be a diploid is a tetraploid. Accessions such as Galeo, Mwitupemba and Ntindi 1 that were previously classified as triploids were found diploids. GT, FHIA 25 and Muzungu Mwekundu that were considered as tetraploids, were found triploids. The information generated will guide correct placement of these accessions in the regional germplasm collection centre for the East and Central Africa and their utilization in banana breeding

Selection of cooking banana genotypes for yield and black Sigatoka resistance in different locations in Uganda

It is imperative to systematically evaluate new banana genotypes in different locations before national release. This enables selection and recommendation of superior genotypes as new varieties for a wider range of environments. The objective of the present study was to select banana genotypes with stable and high performance for bunch yield and leaf black Sigatoka resistance. Eleven cooking banana genotypes developed by the Uganda National Agricultural Research Organization in collaboration with Bioversity International, and two check varieties were evaluated in multi-location preliminary yield trials in Uganda. Data collected were analyzed using Additive Main Effects and Multiplicative Interaction (AMMI) model, AMMI Stability Value, and Genotype Selection Index (GSI). Genotype × location interaction was significant for all the traits assessed. Most of the new genotypes had low interaction effects with locations for bunch yield (69.2%) and black Sigatoka (92.3%). The most stable genotypes for bunch yield were NABIO815, NABIO1117, NABIO216 and NABIO306 whereas for black Sigatoka resistance, were NABIO1011, NABIO815, NABIO1009 and NABIO216. Using the GSI that defines the most desirable genotypes as those that combine high agronomic performance and stability across environments, four genotypes (NABIO306, NABIO1011, NABIO808 and NABIO1009) were selected. These genotypes, in addition to their high performance for agronomic traits and stability, had soft and yellow fruit pulp on cooking, and will be advanced on farm for further evaluatio

Development of two high-yielding, consumer-acceptable apple banana hybrids (Musa species, AAB genome group) with resistance to Fusarium oxysporum f. sp. cubense race 1

Fusarium wilt of bananas (Musa species) is caused by Fusarium oxysporum f. sp. cubense (Foc). Foc race 1 in particular affects dessert bananas in Uganda, causing >60% yield loss. This study was conducted to assess the performance of two new apple banana genotypes for bunch yield, resistance to Foc race 1 and consumer acceptability. The new apple banana genotypes (NAMU1 and NAMU2), along with two check cultivars, one susceptible but preferred by consumers (Sukali ndiizi) and the other resistant (Yangambi-KM5), were evaluated at the National Agricultural Research Laboratories in Uganda. Bunch yields of the two new apple bananas were higher than those of check cultivars by >50%. NAMU1 and Yangambi-KM5 showed no symptoms of Foc race 1, whereas NAMU2 showed mild symptoms on its corms. Sukali ndiizi showed severe pseudostem splitting and corm discoloration as the key symptoms of Foc race 1. The consumer acceptability of NAMU1 and NAMU2 was as high as that of Sukali ndiizi, implying that they can be perfect substitutes for the Foc race 1 susceptible Sukali ndiizi

Testing for a Suitable Culture Medium for Micropropagation of East African Highland Bananas

A study was conducted to find a suitable culture medium for micropropagation of East African highland bananas ( Musa spp.). Modified Eriksson (ER), Gamborg\u2019s B-S (B-S) and Murashige-Skoog (MS) media were tested with a roasting cultivar Gonja-Horn plantain (AAB), a dessert Bogoya-Gros Michel (AAA) and three East African highland cooking (AAA) cultivars Kibuzi, Mbwazirume and Namwezi for in vitro proliferation induction. The media were supplemented with 4.5 mg l -1 Benzylaminopurine (BAP) and with or without 0.186 mg l -1 Naphtalene acetic acid (NAA). Only ER and MS gave proliferation. AAB cultivar proliferated significantly more than AAAs which did not differ among themselves. The AAA cultivars showed precocious rooting in the absence and presence of 0.186 mg l -1 NAA on ER and MS media supplemented with 4.5 mg l -1 BAP. However, the presence of auxin NAA significantly lowered shoot proliferation with concomitant significant induction of precocious rooting. This indicated a high level of endogenous auxin in these cultivars and, therefore, the unnecessity of exogenous auxin for their maximum in vitro proliferation. It was also found that ammonical nitrogen content determined the suitability of a culture medium thus making ER an alternative to the MS salts

Improved callogenesis and plant regeneration from immature male flowers of East African highland banana cv. “Nakitembe” (AAA-EA)

Application of biotechnological tools in breeding, germplasm conservation and propagation of the East African bananas (Musa sp.) is limited by the crop’s recalcitrance to somatic embryogenesis. This study was undertaken to establish an efficient callus induction and plant regeneration protocol from immature male flowers in the most commercial and farmer preferred banana cultivar “Nakitembe”. Embryogenic callusing was improved from 2.9% on conventional MA1 culture medium to 4.2% with 500 mg L-1 L-Glutamine, 500 mg L-1 L-Proline and 300 mg L-1 casein hydrolysate supplements. A combination of the three amino acids with Chui N6 salts yielded the highest callusing of 10.2%. Cell suspensions were developed and maintained on conventional MS based MA2 medium. Subsequently, the highest efficiency of embryos germination (up to 80%) was achieved on MA4 medium, supplemented with 2.25 mg L-1 BAP and 0.2 mg L-1 IAA. The developed protocol has been successfully applied in Agrobacterium mediated genetic transformations of this variety

Improved callogenesis and plant regeneration from immature male flowers of East African highland banana cv. \u201cNakitembe\u201d (AAA-EA)

Application of biotechnological tools in breeding, germplasm conservation and propagation of the East African bananas ( Musa sp.) is limited by the crop\u2019s recalcitrance to somatic embryogenesis. This study was undertaken to establish an efficient callus induction and plant regeneration protocol from immature male flowers in the most commercial and farmer preferred banana cultivar \u201cNakitembe\u201d. Embryogenic callusing was improved from 2.9% on conventional MA1 culture medium to 4.2% with 500 mg L-1 L-Glutamine, 500 mg L-1 L-Proline and 300 mg L-1 casein hydrolysate supplements. A combination of the three amino acids with Chui N6 salts yielded the highest callusing of 10.2%. Cell suspensions were developed and maintained on conventional MS based MA2 medium. Subsequently, the highest efficiency of embryos germination (up to 80%) was achieved on MA4 medium, supplemented with 2.25 mg L-1 BAP and 0.2 mg L-1 IAA. The developed protocol has been successfully applied in Agrobacterium mediated genetic transformations of this variety.L\u2019application des outils biotechnologiques dans la s\ue9lection, la conservation du mat\ue9riel g\ue9n\ue9tique et la propagation des bananiers d\u2019Afrique de l\u2019Est ( Musa sp.) est limit\ue9e par la r\ue9ticence de la culture \ue0 l\u2019embryogen\ue8se somatique. Cette \ue9tude a \ue9t\ue9 entreprise pour \ue9tablir un protocole efficace d\u2019induction des cals embryog\ue8nes et de r\ue9g\ue9n\ue9ration des plantes \ue0 partir de fleurs m\ue2les immatures dans le cultivar de bananier le plus commercial et pr\ue9f\ue9r\ue9 des agriculteurs \uab Nakitembe \ubb. Les callosit\ue9s embryog\ue8nes ont \ue9t\ue9 am\ue9lior\ue9es de 2,9% sur le milieu de la culture MA1 conventionnel \ue0 4,2% avec des suppl\ue9ments de 500 mg L-1 L-Glutamine, 500 mg L-1 L-Proline et 300 mg L-1 d\u2019hydrolysat de cas\ue9ine. Une combinaison des trois acides amin\ue9s avec des sels de Chui N6 a donn\ue9 le cal embryog\ue8ne le plus \ue9lev\ue9 de 10,2 %. Des suspensions cellulaires ont \ue9t\ue9 d\ue9velopp\ue9es et maintenues sur un milieu MA2 \ue0 base de MS conventionnel. Par la suite, l\u2019efficacit\ue9 la plus \ue9lev\ue9e de la germination des embryons (jusqu\u2019\ue0 80 %) a \ue9t\ue9 obtenue sur le milieu MA4 compl\ue9t\ue9 par 2,25 mg L-1 de BAP et 0,2 mg L-1 d\u2019IAA. Le protocole d\ue9velopp\ue9 a \ue9t\ue9 appliqu\ue9 avec succ\ue8s dans les transformations g\ue9n\ue9tiques induites par Agrobacterium de cette vari\ue9t\ue9