Characterizing subgenome recombination and chromosomal imbalances in banana varietal lineages.

BACKGROUND: Bananas and plantains (Musa spp.) are among the most important crops worldwide. The cultivated varieties are vegetatively propagated, so their genetic diversity is essentially fixed over time. Musa acuminata, M. balbisiana and M. schizocarpa have provided the named A, B and S subgenomes that predominantly constitute these varieties. Here we aimed to characterize intergenetic recombination and chromosomal imbalances between these A/B/S subgenomes, which often result in copy-number variants (CNVs) leading to changes in gene dosage and phenotype, in a diverse panel of bananas and plantains. This will allow us to characterize varietal lineages better and identify sources of genetic variation. METHODS: We delimited population structure and clonal lineages in a diverse panel of 188 banana and plantain accessions from the most common cultivars using admixture, principal component and phylogenetic analyses. We used new scalable alignment-based methods, Relative Averaged Alignment (RAA) and Relative Coverage, to infer subgenome composition (AA, AAB, etc.) and interspecific recombination. RESULTS: In our panel, we identified ten varietal lineages composed of somatic clones, plus three groups of tetraploid accessions. We identified chromosomal exchanges resulting in gains/losses in chromosomal segments (CNVs), particularly in AAB and ABB varieties. CONCLUSIONS: We demonstrated alignment-based RAA and Relative Coverage can identify subgenome composition and introgressions with similar results to more complex approaches based on single nucleotide polymorphism (SNP) databases. These ab initio species-agnostic methods can be used without sequencing a panel of wild ancestors to find private SNPs, or in recently diverged pools where private SNPs are uncommon. The extensive A/B/S exchanges and the variation in the length of some introgressions between lineages further support multiple foundational events of hybridization and residual backcrossing. Imbalances between A/B/S may have resulted in CNVs and gene dosage variation. Since most edible banana genomes are fixed on time, these CNVs are stable genetic variations probably associated with phenotypic variation for future genetic studies.

Influence of contrasting cultivation altitudes on the physicochemical, digestive, and functional properties of four Musa starches produced in Cameroon.

BACKGROUND: Bananas and plantains are important food sources for many people in the world. Their high starch content places them among the highest energy providers. This study aimed to determine the effects of altitude on banana starch properties in Cameroon. A dessert banana, a cooking banana, a plantain cultivar, and a plantain-like hybrid were grown at low and high altitudes (respectively at 80 m and 1300 m above sea level). RESULTS: Starch analyses showed an increase in moisture and pH values against a drop in total titratable acidity and dry matter content with respect to altitude. Amylose content, as well as water absorption capacity, oil absorption capacity and syneresis of high-altitude plantain and plantain-like hybrid, were significantly higher. Starch digestibility was low and ranged between 13.4% and 37.9% after 2 h of incubation. High-altitude plantain starches contained more amylose and were more resistant to enzymatic hydrolysis. CONCLUSION: Starches from CARBAP K74 and Kelong mekintu, grown at high altitude, showed good water and oil absorption capacities, low digestibility, and high resistance. The adequate properties of these banana starches predispose them for use as thickeners and gelling agents as well as ingredients for the formulation of low-calorie foods. This study highlights the importance of altitude when discussing banana and plantain starch properties. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Mercury waste from artisanal and small-scale gold mining facilities: a risk to farm ecosystems-a case study of Obuasi, Ghana.

Frequent discharge of mercury waste from artisanal and small-scale gold mining (ASGM) facilities into nearby farms may contaminate foodstuffs and the entire farms. High contamination levels may result in ecological risks to the soil, plants, animals, humans, and the entire farm ecosystem. This original research is the first study within the catchment areas that describes the effects of mercury waste on the entire farm ecosystem. In this study, the contamination levels and the associated ecological risks of farmland soils, plantains, and cassavas from farms sited near ASGM facilities in four communities around Obuasi, Ghana, were evaluated using the Hakanson (1980) model. Results showed that all samples except for the edible parts of plantains from Tweapease, Nyamebekyere, and Ahansonyewodea and plantain peels from Nyamebekyere and Ahansonyewodea were contaminated and may pose moderate to very high ecological risks. All farms were also contaminated and may pose considerable to very high ecological risks. The farms at Odumase were the highest contaminated with degree of contamination (Cdeg) above 20, while those at Ahansonyewodea were the least contaminated with Cdeg = 8.1. This meant that farms at Odumase may pose the highest potential ecological risk (Per) to plants, animals, humans, and the entire farm ecosystem since Per > 600, while the farms at Ahansonyewodea may pose the least ecological risks with Per = 324. There is, therefore, the need for strict control of ASGM activities in these study areas to preserve the integrity of the ecosystem.

Scientific opinion on the import of Musa fruits as a pathway for the entry of non-EU Tephritidae into the EU territory.

Following a request from the European Commission, the EFSA Panel on Plant Health examined evidence as to whether the import of fruits of Musa (bananas and plantains) could provide a pathway into the EU for Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) or other non-EU Tephritidae for which Musa is a host. Relevant scientific and technical information, including unpublished information provided to the EFSA Panel on Plant Health by the European Commission from research conducted in Cabo Verde, were taken into account. The majority of EU imports of Musa fruit comes from Ecuador, Colombia and Costa Rica where B. dorsalis does not occur. Commercial Musa fruits are harvested at 'green stage one' before they begin to ripen naturally. Postharvest processes are designed to ensure that only high quality, unripe fruit are exported. Green stage one fruit are transported to the EU in controlled conditions and stimulated to ripen when exposed to exogenous ethylene in ripening rooms in the EU. There is no evidence that any Tephritidae can naturally infest commercial varieties of Musa fruit at green stage one or earlier. When experimentally infested with eggs of Tephritidae, larvae fail to develop in green stage one fruit. Physical and chemical changes that occur during fruit ripening enable B. dorsalis and 11 other species of Tephritidae to oviposit and develop in Musa at later stages of fruit development. Reports of B. dorsalis or other Tephritidae infesting bunches of Musa fruit are a consequence of the fruit being left to develop beyond green stage one in the field. There is no evidence that commercially grown fruits of Musa, for export to the EU, provide a pathway for the entry of non-EU Tephritidae. Passengers bringing Musa fruit from countries where Tephritidae can infest ripened Musa fruit do however provide a potential pathway for the entry of non-EU Tephritidae into the EU territory.

Plantains: Gluco-friendly usage.

Plantains are a staple food for a large proportion of the world's population. Rich sources of carbohydrates, they are considered taboo by most diabetes care providers. For persons living with diabetes, however, they are a preferred food item. This multi country authored article discusses the nutritional and culinary qualities of plantains. It discusses how to consume the fruit in a glucose-safe manner, by reducing the glycaemic load and total caloric load due to a low glycaemic index. Simple ways of modifying plantain preparation and serving are suggested, to help patients take this foodstuff without impacting glucose control.

Ploidy level and nucleotide variations in inflorescence dichotomous cultivars of plantain (Musa spp. AAB genome).

BACKGROUND: Inflorescence dichotomy in Musa species is a rare developmental event which leads to the production of multiple bunches on a single pseudostem at fruiting. In spite of its fascinating attraction and seductive appeal, little is known about the cytogenetic basis and molecular mechanisms that could be ascribed to this phenomenon. To bridge this gap in information, an integrative approach using cytological fingerprinting and DNA ploidy level profiling (based on chromosome counting and flow cytometry) were assayed on five inflorescence dichotomous plantain varieties and a single-bunching cultivar that served as control. This was done to assess the number and behaviour of chromosomes on the one hand and single nucleotide polymorphisms identified during analysis of nucleotide variations on the other. RESULTS: Chromosomes stained with aceto-orcein were very tiny, compact, metacentric and acrocentric, and differed both in number and ploidy level between the inflorescence dichotomous and single-bunching cultivars. The dichotomous plantains were mainly diploid (2n = 2x = 22) while the single-bunching 'Agbagba' cultivar was consistently a triploid (2n = 3x = 33), as revealed by histological chromosome counting and flow cytometry, implying that there was a high incidence of genomic divergence on account of ploidy variations among the different Musa cultivars. Molecular genotyping using single nucleotide polymorphisms detected on the GTPase-protein binding gene of the leaf tissue gene complex provided further evidence indicating that differences in the number of bunches among the inflorescence dichotomous cultivars could be ascribed to nucleotide diversity that was elicited by changes in amino acid sequences in the genome of the crops. Non-synonymous nucleotide substitutions resulted mainly from transversion (from purine to pyramidine and vice versa), tacitly implying that these changes were crucial and promoted a cascade of reactions in the genome that were, probably, responsible for the non-persistence of the dichotomization event(s) or the reversals in the bunch phenotype detected among the inflorescence dichotomous cultivars. CONCLUSIONS: This is the first report of cytogenetic fingerprints and nucleotide diversity detection among single- and multiple-bunching Musa cultivars. A clear distinction between the two groups was found that is indicative of variations both in ploidy level and nucleotide sequences. The pattern of single nucleotide polymorphisms provided profound clues suggesting that there was a high incidence of genomic divergence, due to random and unstable genetic events that were triggered by frequent spontaneous somatic mutations.

Respuesta de cultivares de Musa spp. al estrés hídrico in vitro inducido con polietilenglicol 6000 / Responses of Musa spp. cultivars to in vitro water stress induced with polyethylene glycol 6000

RESUMEN Los plátanos y bananos son cultivos sensibles al déficit hídrico. Las sequías cada vez más prolongadas sugieren la necesidad de obtener plantas tolerantes a este factor; la selección temprana de estas plantas, comparada con la selección en campo, permite ahorrar tiempo y trabajar con mayores volúmenes de individuos. Para ello es conveniente contar con cultivares patrones cuya respuesta al déficit hídrico in vitro sea favorable. El objetivo del presente trabajo fue determinar la respuesta de cultivares de Musa spp. con diferente composición genómica al estrés hídrico inducido in vitro con polietilenglicol 6000 (PEG-6000). Se estudiaron los cultivares 'Pelipita' (ABB), 'Manzano' (AAB) y 'Grande naine' (AAA). El estrés se indujo con 30 g/L de PEG-6000 en medio de cultivo semisólido de multiplicación. A los 30 días se evaluaron variables indicadoras de estrés morfológicas (altura y número de brotes por explante), fisiológicas (masa fresca y masa seca) y bioquímicas (contenido prolina, peróxido de hidrógeno y malondialdehido). En el cultivar 'Pelipita' se afectó solamente la altura de las plantas, mientras que en los demás se afectaron todas las variables excepto la masa seca en el 'Manzano'. En este último y en el 'Grande naine' se incrementó la prolina, el peróxido de hidrógeno y el malondialdehido, lo que evidenció un mayor estrés oxidativo y daño en las membranas celulares. Los cultivares estudiados, pudieran emplearse como controles de tolerancia ('Pelipita') y sensibilidad ('Grande naine' y 'Manzano') en la selección in vitro de plantas tolerantes a la sequía, en futuros programas de mejoramiento genético.

ABSTRACT Bananas and plantains are crops very sensitive to water deficit. Increasingly prolonged drought condition suggests the need for tolerant plants to this factor. The early selection of these plants in in vitro conditions save time and allow working with large volumes of individuals. This requires having genotypes with favorable response to in vitro water deficit. The aim of this work was to determine the response of Musa spp. cultivars, with different genotype contribution, to in vitro water stress induced by polyethylene glycol 6000 (PEG-6000). Cultivars 'Pelipita' (ABB), 'Manzano' (AAB) and 'Grande naine' (AAA) were cultured in semisolid multiplication medium supplemented with PEG-6000 30 g/L. Different stress indicator traits were evaluated after 30 days (morphological: height and number of shoots per explant; physiological: fresh and dry weight; and biochemical: proline, hydrogen peroxide and malondialdehyde content). As results, osmotic stress affected only plant height in 'Pelipita' cultivar. However, in the other cultivars all variables were affected, except dry weight in 'Manzano'. Moreover cv. 'Grande naine' and 'Manzano' increased proline, hydrogen peroxide and malondialdehyde content. These results indicate that osmotic pressure could induce oxidative stress and cell membrane damages in these cultivars. The obtained results suggested that these genotypes could be used as a tolerant ('Pelipita') and sensitive ('Grande naine' and 'Manzano') controls in in vitro selection of drought-tolerant plants in future breeding programs.