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The physiochemical, structural, and molecular characteristics of starch influence its functional properties, thereby dictating its utilization. The study aimed to profile the properties and quantity of resistant starch (RS) from 15 different banana varieties, extracted using a combination of alkaline and enzyme treatments. Granular structure and molecular organization were analyzed using light microscopy, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The physiochemical and functional properties were also investigated. RS content ranged from 49% to 80% without significant relationship to amylose (AM) (r = −0.1062). SEM revealed significant microarchitectural differences on the granules potentially affecting granule digestibility. FTIR and chemometrics identified differences in the crystalline peaks, yielding varying degrees of the molecular order of the RS polymers that aid in differentiating the RS sources. Despite similar solubility and swelling profiles, the pasting profiles varied across varieties, indicating high paste stability in hydrothermal processing. Clarity ranged from 43% to 93%, attributed to amylose leaching. This study highlights that RS from bananas varies in quantity, structure, and functionality, necessitating individualized approaches for processing and utilization. [ABSTRACT FROM AUTHOR]

This study assessed the internal quality traits of East African Highland cooking banana flours, exploring their significance for breeding and potential industrial applications. Twenty cultivars (nine hybrids and eleven landraces) were used. Swelling power capacity, water solubility, water absorption capacity, water absorption index, freeze–thawing stability, and pasting characteristics of banana flour were assessed using standard methods. The results showed that cultivars with high swelling power also exhibited a high water absorption capacity and water absorption index, thus making them suitable for bakery industries. The water absorption capacity ranged between 5.66% (N2) and 11.68% (N11). Landraces KBZ (9.01) and NKYK (8.05), and hybrids N11 (11.68) and N9 (8.48) are suitable as thickeners due to high WAC. Hybrids (N7, 27.83%, and N9, 22.59%) and landraces (NMZ, 32.69%, and NFK, 34.24%) had low freeze–thawing stability, hence it is applicable as a food stabilizer. Landrace NKT (19.14%) and hybrid N9 (16.95%) had the highest solubility, and landrace KBZ (6.93%) and hybrid N3 (6.66%) had the lowest solubility. Landraces MSK (6265), NKY (3980), and NFK (3957), and hybrids N6 (3608), N7 (3505), and N9 (3281 RVU) had high peak viscosity. The trough viscosity, final viscosity, and breakdown viscosity of cultivars varied from 422.5 to 5004 RVU. The landraces MSK (5021 RVU) and NFK (4111 RVU) had the highest final viscosity, making them suitable for application in the food industry for thick and stable sauces. Landrace TRZ had the lowest pasting temperature (62.7 °C), making it advantageous for use where fast gelatinization is required, hence saving energy costs and cooking time. These findings suggest that the genetic attributes inherent in cultivars can be incorporated into breeding programs targeting required traits for industrial application. [ABSTRACT FROM AUTHOR]

The burrowing nematode Radopholus similis is considered a major problem of intensive banana cultivation. It can cause extensive root damage resulting in the toppling disease of banana, which means that plants fall to the ground. Soaking R. similis in double-stranded (ds) RNA of the nematode genes Rps13, chitin synthase (Chs-2), Unc-87, Pat-10 or beta-1,4-endoglucanase (Eng1a) suppressed reproduction on carrot discs, from 2.8-fold (Chs-2) to 7-fold (Rps13). The East African Highland Banana cultivar Nakitembe was then transformed with constructs for expression of dsRNA against the same genes, and for each construct, 30 independent transformants were tested with nematode infection. Four months after transfer from in vitro culture to the greenhouse, the banana plants were transferred to a screenhouse and inoculated with 2000 nematodes per plant, and thirteen weeks later, they were analyzed for several parameters including plant growth, root necrosis and final nematode population. Plants with dsRNA constructs against the nematode genes were on average showing lower nematode multiplication and root damage than the nontransformed controls or the banana plants expressing dsRNA against the nonendogenous gene. In conclusion, RNAi seems to efficiently protect banana against damage caused by R. similis, opening perspectives to control this pest. [ABSTRACT FROM AUTHOR]

Sterility in edible bananas is as a result of a long history of anthropogenic-driven selection for sterile genotypes, since seed is not desirable in fruit pulp for human consumption. However, this poses a challenge to conventional genetic improvement by slowing breeding pipelines. In this study, we investigated whether pollen tubes reach all parts of the ovary, the position of fertilized ovule development in fruits, and potential seed set in selected banana genotypes. We selected four cultivars of East African Highland Cooking bananas (EAHBs), a Matooke hybrid '222K-1', improved diploid '2905', and wild bananas 'Zebrina (G.F.)' and 'Calcutta 4'. There was evidence of pollen tubes in the distal, mid and proximal sections of the fruit, irrespective of hand position and genotype. Fertilization, as indicated by an increase in ovule size, happened along the entire length of the fruit but complete development was biased at the distal end in some genotypes. There were some differences in ovule fertilization rates between hands, with distal hands having more ovules and higher ovule fertilization rates. Ovule fertilization happens in bananas but the vast majority aborts, especially at the proximal end of the ovary. Ovule fertilization rates are generally much lower than available ovules. [ABSTRACT FROM AUTHOR]

Seed set in banana is influenced by weather, yet the key weather attributes and the critical period of influence are unknown. We therefore investigated the influence of weather during floral development for a better perspective of seed set increase. Three East African highland cooking bananas (EAHBs) were pollinated with pollen fertile wild banana ‘Calcutta 40 . At full maturity, bunches were harvested, ripened, and seeds extracted from fruit pulp. Pearson’s correlation analysis was then conducted between seed set per 100 fruits per bunch and weather attributes at 15-day intervals from 105 days before pollination (DBP) to 120 days after pollination (DAP). Seed set was positively correlated with average temperature (P < 0.05–P < 0.001, r = 0.196–0.487) and negatively correlated with relative humidity (RH) (P < 0.05–P < 0.001, r = −0.158–−0.438) between 75 DBP and the time of pollination. After pollination, average temperature was negatively correlated with seed set in ‘Mshale’ and ‘Nshonowa’ from 45 to 120 DAP (P < 0.05–P < 0.001, r = −0.213–−0.340). Correlation coefficients were highest at 15 DBP for ‘Mshale’ and ‘Nshonowa’, whereas for ‘Enzirabahima’, the highest were at the time of pollination. Maximum temperature as revealed by principal component analysis at the time of pollination should be the main focus for seed set increase. [ABSTRACT FROM AUTHOR]

The bacterium Xanthomonas campestris pathovar musacearum (Xcm) is the causal agent of banana Xanthomonas wilt (BXW). This disease has devastated economies based on banana and plantain crops (Musa species) in East Africa. Here we use genome-wide sequencing to discover a set of single-nucleotide polymorphisms (SNPs) among East African isolates of Xcm. These SNPs have potential as molecular markers for phylogeographic studies of the epidemiology and spread of the pathogen. Our analysis reveals two major sub-lineages of the pathogen, suggesting that the current outbreaks of BXW on Musa species in the region may have more than one introductory event, perhaps from Ethiopia. Also, based on comparisons of genome-wide sequence data from multiple isolates of Xcm and multiple strains of X. vasicola pathovar vasculorum, we identify genes specific to Xcm that could be used to specifically detect Xcm by PCR-based methods. [ABSTRACT FROM AUTHOR]

Simple Summary: RNA interference (RNAi), a conserved mechanism in eukaryotic organisms, is initiated by the presence of double-stranded RNA (dsRNA) in the cells, regulating the expression of specific genes by degradation of their mRNA, and it is known as post-transcriptional gene-silencing (PTGS). RNAi can be employed to develop species-specific biopesticides where dsRNA is delivered to a pest insect via the oral route. Banana weevil (Cosmopolites sordidus) is the most devastating pest of banana and plantain worldwide, yet current control measures are neither effective, sustainable, nor environmentally sound. This study reports an artificial diet-based multi-well plate method and the first findings on the potential application of biotechnology in the control of the banana weevil using dietary RNAi, which would arguably provide the most sustainable and practical method for dsRNA delivery. A selection of target genes with effective RNAi leading to high and rapid mortality is presented. These results indicate the potential of RNAi-mediated management to suppress C. sordidus efficiently in the banana crop. Banana weevil (Cosmopolites sordidus) is the most devastating pest of banana and plantain worldwide, yet current control measures are neither effective, sustainable, nor environmentally sound, and no resistant farmer-preferred cultivars are known to date. In this paper, we examined the ability to induce RNA interference (RNAi) in the banana weevil via feeding. We first developed an agar- and banana corm (rhizome) flour-based artificial diet in a multi-well plate setup that allowed the banana weevils to complete their life cycle from egg through the larval instars to the pupal stage in an average period of 53 days. Adults emerged about 20 days later. The artificial diet allowed the tunneling and burrowing habits of the larvae and successful metamorphosis up to adult eclosion. Adding dsRNA for laccase2 to the artificial diet resulted in albino phenotypes, confirming gene-silencing. Finally, C. sordidus was fed with dsRNA against a selection of essential target genes: snf7, rps13, mad1, vha-a, vha-d, and lgl for a period of 45 days. 100% mortality within 9–16 days was realized with dssnf7, dsrps13, and dsmad1 at 200 ng/mL artificial diet, and this corresponded to a strong reduction in gene expression. Feeding the dsRNA targeting the two vha genes resulted in 100% mortality after about 3–4 weeks, while treatment with dslgl resulted in no mortality above the dsgfp-control and the water-control. Our results have implications for the development of RNAi approaches for managing important crop pests, in that banana weevils can be controlled based on the silencing of essential target genes as snf7, rps13, and mad1. They also highlight the need for research into the development of RNAi for banana protection, eventually the engineering of host-induced gene-silencing (HIGS) cultivars, given the high RNAi efficacy and its species-specific mode of action, adding the RNAi approach to the armory of integrated pest management (IPM). [ABSTRACT FROM AUTHOR]

Seed set in East African Highland Cooking bananas (EAHBs) is extremely low and therefore hampers breeding. Pollen–pistil interaction is a key contributing factor. We assessed the effect of pollen germination media (PGM) on seed set in EAHBs. Five EAHB cultivars were pollinated with pollen from the wild banana 'Calcutta 4'. Glucose-based PGM sprayed on freshly emerged stigmas significantly increased seed set per 100 fruits per bunch. Increases were 73.5% in 'Enzirabahima', 39.9% in 'Mshale', and 302.4% in 'Nshonowa'. However, PGM did not increase seed set in the female sterile 'Mlelembo' and 'Nakitembe'. As larger bunches were more fertile, good field management practices are also recommended to get more seed to improve breeding efficiency. [ABSTRACT FROM AUTHOR]

Low female fertility in bananas is the biggest hurdle for banana breeding. The aim of this study was to determine seed set patterns in East African Highland Cooking bananas (EAHBs) to inform future decisions on a more targeted approach of increasing seed set and subsequently banana-breeding efficiency. Matooke (AAA) and Mchare (AA) bananas are genetically distinct but belong to the same genetic complex, referred to as EAHBs. Seed set patterns in "Enzirabahima" (AAA), "Mshale" (AA), and "Nshonowa" (AA), all with residual fertility, were examined after hand pollination with a highly male fertile wild banana "Calcutta 4" (AA). Seed set in "Enzirabahima" is predominant in distal hands. Mchare cultivars have a slightly more even distribution of seeds in their hands compared to "Enzirabahima". There is a gradual increase in seed set from proximal to distal hands with a slight drop in the last hand. This pattern is more definite in "Enzirabahima" and "Mshale", while "Nshonowa" has a somewhat inconsistent pattern. There is also a drop in seed set per 100 fruits per hand from small to larger bunches. However, larger bunches have a higher pollination success compared to smaller bunches. They therefore set more seed on 100 fruits per hand and per bunch basis, if bunches without seed are accounted for. Pollination success rate increases from smaller to larger bunches of EAHBs. Seed set is biased toward the distal third part of fruits of examined EAHBs, as well as tetraploid Matooke hybrid "401K-1" (AAAA), and improved diploid "Zebrina" GF (AA) that were used for comparison. In comparison, in the highly female fertile "Calcutta 4", seed set is along the entire length of the fruit. Seed set bias in the distal hands and distal end of fruits suggests a systematic mechanism rather than a random occurrence. It is expected that this information will provide a foundation for increased crossbreeding efficiency in bananas. [ABSTRACT FROM AUTHOR]

Banana Xanthomonas Wilt (BXW) is an important emerging and non-curable infectious plant pathogen in sub-Saharan Africa that can cause up to 100% yield loss, negatively impacting sustainable access to food and income to more than 100 million banana farmers. This study disentangles adopters into partial and full adopters to investigate the factors that are relevant to sustain the adoption process of BXW control practices and quantifies the impact of adopting the practices. Data from a randomly selected sample of 1200 banana farmers in Uganda where the disease is endemic was used. A multinomial logit model was used to determine the factors affecting adoption of control practices and augmented inverse probability weighting was employed to estimate the impacts of adoption on banana productivity and sales. Results show that training a woman farmer and having diverse sources of information about BXW control practices increased adoption of the control practices and reduced the disease incidences. Farmers who adopted all the recommended control practices achieved significantly the highest values of banana production and sales. We conclude that improving information access through farmers' preferred communication channels, having women-inclusive trainings, and a combination of cultural practices are effective ways for sustaining adoption of the control practices. [ABSTRACT FROM AUTHOR]