The potential of using botanical insecticides for the control of the banana weevil, Cosmopolites sordidus(Coleoptera: Curculionidae)

Crude extracts of chinaberry tree (Melia azedarach L.), mexican marigold (Tagates spp.), water hyacinth (Eichornia crassipes, Martius) and Castor oil (Ricinus communis L.) were tested for their effect onweevil mortality, settling responses and oviposition in the laboratory. All extracts of the botanicals did not show significant effects on weevil mortality compared to controls. Weevil settling responses oncorms treated with extracts of botanicals compared to controls were statistically similar after 1 h and 72 h of observation. Oviposition was significantly low on corms treated with M. azedarach, Tagetes sppand R. communis compared to controls. Oviposition on corms treated with water hyacinth extracts was not statistically different from oviposition on controls. The data indicates that botanicals possess limited insecticidal properties but the potential of M. azedarach, Tagetes spp and R. communis to control the weevil through preventing oviposition needs further investigation

Community mobilization: a key to effective control of banana Xanthomonas wilt

Banana xanthomonas wilt (BXW) remains a major threat to banana, an important food and income crop for 12 million poor small-holder farmers in Uganda. Although, BXW has been controlled to some extent in parts of South-western Uganda, it is still a big problem in banana growing areas of Central and Eastern Uganda. We hypothesized that differential success in BXW control is mainly due to approaches used in the BXW control. This paper therefore, evaluates stakeholder mobilization approaches used in promoting technologies for BXW control in Uganda between 2006 and 2009. Results showed that farmer field schools host communities had more farmers (33%) that had low or no BXW infection (<10 infected plants) as compared to smaller proportions (23.5%) of farmers from communities that were using community action or that were mobilised using the traditional approach (22.9%) to control BXW. There was higher BXW prevalence in communities that were using community action (68.8%) or were mobilised traditionally (66.3%) than in those that hosted farmer field schools (43.4%). Consequently, there was higher (53%) banana production recovery on farms that hosted farmer field schools than those that used other institutional approaches (22%). BXW was better controlled by farmers mobilised using farmers field schools than those mobilized through community or traditional approaches

Rep-PCR reveals a high genetic homogeneity among Ugandan isolates of Xanthomonas campestris pv musacearum

Wilting of plants incited by a bacterium, Xanthomonas campestris pv musacearum (Xcm), was first described on Ensete (Ensete ventricosum) and later bananas (Musa species) in the highlands ofEthiopia in 1968. Although the spread outside Ethiopia remained unreported for several decades, an epidemic of the disease on banana in Uganda was observed in 2001, in the districts of Mukono andKayunga. Since then, the disease has spread into almost three quarters of the major banana growing areas in Uganda. It has also been confirmed affecting banana plantations in the Democratic Republic ofCongo (DRC) and Rwanda. Repetitive sequence based genomic fingerprinting that uses a PCRmediated amplification of DNA sequences located between specific interspersed sequences of highlyconserved elements in prokaryotic genomes was used to characterize a collection of Xcm isolates from banana in Uganda. Fingerprints of bacterial isolates collected from Xcm symptom bearing bananaplants grown in production fields from 10 districts including Kayunga, Masindi, Luwero, Kampala, Kiboga, Lira, Wakiso, Kibale and Nakasongola revealed similar patterns. Cluster analysis of pair wisesimilarity values performed using unweighted pair group method with arithmetic averages clustering technique did not generate any differences in the fingerprint patterns either. The implications of thisgenetic homogeneity on the origin and management of Xcm is discussed here

Genetically engineered East African highland bananas – proximate analysis and effect of cooking on the enhanced provitamin A levels

Micronutrient deficiency is a major challenge in the developing world. This is mainly attributed to over-reliance on starchy staples foods such as cassava, rice and banana among others, which are deficient in micronutrients such as vitamin A and iron. Strategies put in place to provide a solution to micronutrient deficiencies such as dietary supplementation of vitamin A and food fortification have not been successful in the developing world due to high costs and unreliable supply chains (food and medical). Biofortification of the easily accessible staple foods could help reduce this problem associated with micronutrient deficiency. On this account, the Biofortification project in Uganda under the National Banana Program developed transgenic East African Highland Bananas (EAHBs) (M9 and Nakitembe) with enhanced levels of provitamin A (PVA) using the Fe’i banana-derived phytoene synthase 2a (MtPsy2a) gene. To determine the nutritional quality of the transgenic bananas, an analysis of the proximate composition of the biofortified East African Highland Bananas was carried out. The effect of cooking on retention of provitamin A carotenoids (pVAC), was assessed using two cooking methods; boiling and steaming (most common methods of preparing cooking banana meals in Uganda). It was observed that there were no significant (P≤0.05) differences in moisture content (P=0.4287), carbohydrate (P=0.3966), crude fat (P=0.4051), crude fiber (P=0.3214), protein (P=0.0858) and ash content P=0.1336) between transgenic and non-transformed bananas. It was found that steaming, as a cooking method allowed for retention of more provitamin A carotenoids compared to boiling. Comparison of the cultivars on their retention of provitamin A carotenoids, results indicated that Nakitembe was superior to M9. Genetic engineering of bananas by biofortification has no effect on major food components in EAHBs (M9 and Nakitembe) and, therefore, genetically modified M9 and Nakitembe are substantially equivalent to the non-transgenic controls and the biofortified bananas can provide the necessary nutrients even after cooking. This&nbsp; data will inform subsequent steps for the commercialization of biofortified EAHBs

Agrobacterium mediated transformation of banana (Musa sp.) cv. Sukali Ndiizi (ABB) with a modified Carica papaya cystatin (CpCYS) gene

Conventional banana breeding for pest and disease resistance is a very difficult and slow process due to the limited sources of resistance, sterility of cultivated banana varieties, high polyploidy levels, long cropping cycle and the lack of rapid screening methods. Molecular breeding using the transgenic approach with candidate genes such as cystatins offers an alternative method to banana improvement. Cystatin proteins inhibit the activity of cysteine proteases responsible for the breakdown of dietary proteins in the gut of many pests including nematodes resulting in protein deficiency. In this study, the papaya cystatin gene was introduced into the banana genome. Embryogenic cell suspension (ECS) cultures of the banana cultivar Sukali Ndiizi (ABB) were used as explants material for the successful transformation of banana. The Carica papaya cystatin gene (CpCYS-Mut89) previously modified to improve its inhibitory potential against banana pests was introduced into this cultivar using Agrobacterium tumefaciens, strain LBA4404 and the gus reporter gene was used to observe successful transformation process. We report the successful protocol for routine transformation of this cultivar, which was completed in six months with plant regeneration observed at a frequency of 23%. An additional four months was required to multiply the regenerant lines in order to have at least 20 plants per line for downstream challenging studies. Putatively transgenic plants were analyzed by PCR using hpt and CpCYS-Mut89 specific primers to confirm the presence of transgenes. Out of 28 selected lines, 27 were positive for both hpt and CpCYS-Mut89 transgenes giving 96.4% transformation efficiency. Five lines were then selected on the basis of putative PCR positives and a Southern blot analysis gave hybridization signals with 1 to 4 copy number integration patterns characteristic of Agrobacterium mediated transformation. These results confirm stable gene integration in East African banana cultivar cv. Sukali Ndiizi (genome group ABB) through an efficient Agrobacterium-mediated transformation protocol described for routine use in future improvement of this crop with genes of economic importance.Keywords: Cystatins, banana, Agrobacterium mediated transformation, southern blotAfrican Journal of Biotechnology Vol. 12(15), pp. 1811-181

Agrobacterium mediated transformation of banana (Musa sp.) cv. Sukali Ndiizi (ABB) with a modified Carica papaya cystatin (CpCYS) gene

Conventional banana breeding for pest and disease resistance is a very difficult and slow process due to the limited sources of resistance, sterility of cultivated banana varieties, high polyploidy levels, long cropping cycle and the lack of rapid screening methods. Molecular breeding using the transgenic approach with candidate genes such as cystatins offers an alternative method to banana improvement. Cystatin proteins inhibit the activity of cysteine proteases responsible for the breakdown of dietary proteins in the gut of many pests including nematodes resulting in protein deficiency. In this study, the papaya cystatin gene was introduced into the banana genome. Embryogenic cell suspension (ECS) cultures of the banana cultivar Sukali Ndiizi (ABB) were used as explants material for the successful transformation of banana. The Carica papaya cystatin gene (CpCYS-Mut89) previously modified to improve its inhibitory potential against banana pests was introduced into this cultivar using Agrobacterium tumefaciens, strain LBA4404 and the gus reporter gene was used to observe successful transformation process. We report the successful protocol for routine transformation of this cultivar, which was completed in six months with plant regeneration observed at a frequency of 23%. An additional four months was required to multiply the regenerant lines in order to have at least 20 plants per line for downstream challenging studies. Putatively transgenic plants were analyzed by PCR using hpt and CpCYS-Mut89 specific primers to confirm the presence of transgenes. Out of 28 selected lines, 27 were positive for both hpt and CpCYS-Mut89 transgenes giving 96.4% transformation efficiency. Five lines were then selected on the basis of putative PCR positives and a Southern blot analysis gave hybridization signals with 1 to 4 copy number integration patterns characteristic of Agrobacterium mediated transformation. These results confirm stable gene integration in East African banana cultivar cv. Sukali Ndiizi (genome group ABB) through an efficient Agrobacterium-mediated transformation protocol described for routine use in future improvement of this crop with genes of economic importance.Bioversity International through the National Banana Research Programmme of the National Agricultural Research Organization, Uganda.http://www.academicjournals.org/AJBam201

Genomic prediction in a multiploid crop: genotype by environment interaction and allele dosage effects on predictive ability in banana

Open Access Journal; Published online: 2 March 2018Improving the efficiency of selection in conventional crossbreeding is a major priority in banana (Musa spp.) breeding. Routine application of classical marker assisted selection (MAS) is lagging in banana due to limitations in MAS tools. Genomic selection (GS) based on genomic prediction models can address some limitations of classical MAS, but the use of GS in banana has not been reported to date. The aim of this study was to evaluate the predictive ability of six genomic prediction models for 15 traits in a multi-ploidy training population. The population consisted of 307 banana genotypes phenotyped under low and high input field management conditions for two crop cycles. The single nucleotide polymorphism (SNP) markers used to fit the models were obtained from genotyping by sequencing (GBS) data. Models that account for additive genetic effects provided better predictions with 12 out of 15 traits. The performance of BayesB model was superior to other models particularly on fruit filling and fruit bunch traits. Models that included averaged environment data were more robust in trait prediction even with a reduced number of markers. Accounting for allele dosage in SNP markers (AD-SNP) reduced predictive ability relative to traditional bi-allelic SNP (BA-SNP), but the prediction trend remained the same across traits. The high predictive values (0.47– 0.75) of fruit filling and fruit bunch traits show the potential of genomic prediction to increase selection efficiency in banana breeding

Ralstonia syzygii, the Blood Disease Bacterium and Some Asian R. solanacearum Strains Form a Single Genomic Species Despite Divergent Lifestyles

The Ralstonia solanacearum species complex includes R. solanacearum, R. syzygii, and the Blood Disease Bacterium (BDB). All colonize plant xylem vessels and cause wilt diseases, but with significant biological differences. R. solanacearum is a soilborne bacterium that infects the roots of a broad range of plants. R. syzygii causes Sumatra disease of clove trees and is actively transmitted by cercopoid insects. BDB is also pathogenic to a single host, banana, and is transmitted by pollinating insects. Sequencing and DNA-DNA hybridization studies indicated that despite their phenotypic differences, these three plant pathogens are actually very closely related, falling into the Phylotype IV subgroup of the R. solanacearum species complex. To better understand the relationships among these bacteria, we sequenced and annotated the genomes of R. syzygii strain R24 and BDB strain R229. These genomes were compared to strain PSI07, a closely related Phylotype IV tomato isolate of R. solanacearum, and to five additional R. solanacearum genomes. Whole-genome comparisons confirmed previous phylogenetic results: the three phylotype IV strains share more and larger syntenic regions with each other than with other R. solanacearum strains. Furthermore, the genetic distances between strains, assessed by an in-silico equivalent of DNA-DNA hybridization, unambiguously showed that phylotype IV strains of BDB, R. syzygii and R. solanacearum form one genomic species. Based on these comprehensive data we propose a revision of the taxonomy of the R. solanacearum species complex. The BDB and R. syzygii genomes encoded no obvious unique metabolic capacities and contained no evidence of horizontal gene transfer from bacteria occupying similar niches. Genes specific to R. syzygii and BDB were almost all of unknown function or extrachromosomal origin. Thus, the pathogenic life-styles of these organisms are more probably due to ecological adaptation and genomic convergence during vertical evolution than to the acquisition of DNA by horizontal transfer