Biology subjects

Demissew, S.

Publications and source records attributed to Demissew, S..

9 recordsLinked to original sources

bioRxiv2026

Genetic diversity and population structure of Ethiopian taro Colocasia esculenta (L.) Schott) as revealed by SSR markers

Abstract Taro (Colocasia esculenta (L.) Schott) is an important root and tuber crop that contributes to food security and livelihoods, but its genetic diversity remains poorly characterized in Ethiopia. This study assessed Ethiopian taro genetic diversity and population structure using simple sequence repeat (SSR) markers. We analyzed 119 accessions, 79 collected from farmers fields and 40 from the Ethiopian Biodiversity Institute (EBI), representing three regional populations: South Ethiopia Regional State (SERS), South West Ethiopia Peoples Regional State (SWEPRS), and Oromia. Fifteen polymorphic SSR markers produced 199 reproducible polymorphic loci, with 100% polymorphism. Polymorphism information content (PIC) ranged from 0.300 to 0.888 (mean 0.583). Diversity based on scored binary marker states was relatively low, with a mean effective number of alleles (Ne) of 1.077 and expected heterozygosity (He) of 0.066. Across populations, He ranged from 0.047 to 0.061, and the percentage of polymorphic loci ranged from 37.14% to 82.57%. Analysis of molecular variance showed that 98% of molecular variation occurred within populations and 2% among populations. Genetic differentiation ({Phi}PT, proportion of molecular variation among populations) was weak but significant ({Phi}PT = 0.016, P = 0.016). Principal coordinate analysis, neighbor-joining (NJ), and unweighted pair-group method with arithmetic mean (UPGMA) clustering showed extensive overlap among accessions and no clear geographic structuring. Bayesian clustering identified two groups as the strongest partition according to the {Delta}K criterion, but substantial admixture occurred, and groups did not correspond clearly to geographic populations. Despite relatively low diversity at individual scored loci, all 119 accessions had unique multilocus genotypes, indicating high multilocus genotypic diversity. Most molecular variation occurred within rather than among regional populations, potentially reflecting planting-material exchange and predominantly clonal propagation. These findings provide a basis for conserving, characterizing, and utilizing Ethiopian taro germplasm in crop improvement.

genetics↗

bioRxiv2025

Setting priorities for the acquisition of primary plant occurrence data

AimEffective implementation of the Global Biodiversity Framework and Global Strategy for Plant Conservation depends on accurate species distribution data. Current vascular plant distribution data, while crucial for understanding terrestrial ecosystems, is often sparse and biased and requires significant expansion. This study developed a scalable approach to prioritize areas for plant occurrence data acquisition, adaptable to national priorities and providing a framework for botanical institutions to coordinate efforts and allocate resources. LocationGlobal. MethodsUsing a Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) analysis, we prioritized areas based on: (a) ecosystem service value; (b) floristic value threatened by climate or land-use change; and (c) uncertainty in species richness estimates, stratified by biome and region. Regional prioritization maps for Africa & Madagascar; East, South and Southeast Asia; Siberia and the Russian Far East; South America; and North & Central America were reviewed by botanical experts for validation. Scalability was assessed by comparing regional and global analyses. ResultsData-driven priority maps, divided into tree-dominated and grassland/deforested areas, largely received expert support. High similarity between global and regional maps demonstrated scalability. Main conclusionsOur approach provides a framework for supporting national implementation of the Global Biodiversity Framework. Variables and their weights can be tailored to national or local needs. The methods flexibility and adaptability extend to other taxonomic groups and objectives, such as protected area selection By prioritizing data acquisition, whether field-based or digital, this research promotes the efficient use of resources. A key advantage of this approach is its capacity to systematically translate expert opinion into explicit and quantitative criteria, which in turn facilitates clear communication with policymakers and funders.

plant biology↗

bioRxiv2025

Recurrent evolution of cryptic triploids in cultivated enset increases yield

The high incidence of polyploidy in crops could be explained if domestication involved the selection of polyploids (cytotypes with more than two sets of chromosomes). Ancestral horticulture could have targeted desirable traits including yield, robustness to stress and to disease, rather than requiring knowledge of polyploidy itself. We find evidence for this process underway in enset (Ensete ventricosum, Musaceae) - a highly resilient crop constituting the main staple for over 20 million people in Ethiopia, which is clonally propagated and cultivated for its starch-rich corm and pseudostem. Prior to this study, enset was thought to be exclusively diploid (2n = 2x = 18). Using a newly-assembled chromosome-scale reference genome, and sequence data from 723 wild and domesticated enset individuals from southwestern Ethiopia, we demonstrate that around 20% of cultivated enset clones are triploid. We show that triploidy has arisen multiple times independently, that the triploid lineages have been given distinct landrace names, and planted disproportionately frequently. As well as providing evidence for enduring selection on triploids, our results reveal valuable genetic diversity captured by these triploid lines. They represent key resources for scientifically directed breeding of this major crop in the Ethiopian agrosystem, and could improve food security in sub-saharan Africa. Author SummaryDuplication of a species entire genome (polyploidization) plays an important part in evolution. Domestication may have favoured polyploid crops including wheat, coffee, potato, cotton, strawberry, and banana. It has been proposed that this trend is explained by the selection of advantageous traits exhibited by polyploids compared to their relatives with unduplicated genomes. These desirable traits include bigger fruits, seeds or other edible organs, and better tolerance to stress and disease. We unexpectedly find that a large proportion of cultivated enset lines have three copies of their genome (triploidy) instead of two (diploid). Enset is a highly resilient crop in the banana family; its stem and leaves are processed to provide one of the main food sources for over 20 million people in Ethiopia. Prior to our study, enset was thought to be exclusively diploid. Farmers use landrace names that distinguish diploids from triploids without having this new genetic information, showing the differences between them are recognised and given importance. Triploids were planted disproportionately and appear to grow faster, suggesting they are being selected for their higher productivity. These triploid ensets are an important genetic resource for scientifically directed breeding of new varieties, which could improve food security in sub-saharan Africa.

evolutionary biology↗

bioRxiv2022

Introduced crops supplement rather than replace indigenous crops in an African center of agrobiodiversity

O_LICrop diversity plays a major role in underpinning food security. It is especially important to smallholder and subsistence farmers, who often rely on crop diversity for stable and resilient production. Despite this, global expansion of a small pool of major crops and the associated homogenisation of global agricultural systems may decrease on-farm crop diversity. C_LIO_LIWe surveyed 1,369 subsistence farms stratified across climate gradients in the Ethiopian Highlands, to characterise the richness and cultivated area of the 83 edible crops they contained. We further categorise these crops by their period of introduction to Ethiopia. We apply non-metric multidimensional scaling and mixed effects modelling to characterise agrisystem composition and test the impact of crop introductions. C_LIO_LIWe find a significant positive relationship between introduced and indigenous crop richness, suggesting that crop introductions have tended to supplement rather than replace or reduce indigenous crop diversity. Geographically matched farms with higher proportions of introduced crops, had significantly higher overall crop richness. Analysis of socio-economic drivers indicates that both poverty and low accessibility are associated with reduced cultivation of modern introductions. C_LIO_LIWe conclude that global patterns of major crop expansion do not necessarily result in agrobiodiversity loss for subsistence farmers, in our Ethiopian case study. Importantly, socioeconomic factors may strongly influence the farmers propensity to adopt novel species, suggesting targets for agricultural extension policies. Given the rapid climatic, economic and demographic changes impacting global food systems and the threats to food security these entail, robust indigenous agricultural systems supplemented with diverse introduced crops may enhance resilience. C_LI

ecology↗

bioRxiv2021

Land Use Cover changes in the western escarpment of Rift Valley in the Gamo Zone, Southern Ethiopia

LULC changes are caused by natural and human alterations of the landscape that could largely affect forest biodiversity and the environment. The aim of the study was to analyzed LULC change dynamics in the western escarpment of the rift valley of the Gamo Zone, Southern Ethiopia. Digital satellite images downloaded from USGS were analyzed using ERDAS Imagine (14) and Arc GIS 10.2 software and supervised image classification was used to generate LULC classification, accuracy assessment and Normalized Difference Vegetation Index (NDVI). Drivers of LULC change were identified and analyzed. Four land classes were identified such as forest, farmland, settlement and water-wetland. Settlement and farmlands have increased by 7.83% and 5.88%, respectively. On the other hand, both forest and water bodies and wetland decreased by aerial coverage of 11.03% and 2.68%, respectively. The overall accuracy of the study area was 92.86%, 94.22% and 94.3% with a kappa value of 0.902, 0.92 and 0.922, respectively. NDVI values ranged between -0.42 to 0.73. Agricultural expansion (31.4%), expansion of settlement (25.7%) and Fuelwood collection and Charcoal production (22.9%) were the main driving forces that jeopardize forest biodiversity of the study area. Integrated land use and policy to protect biodiversity loss, forest degradation and climate changes are deemed necessary.

ecology↗

bioRxiv2020

Trends in plant ecology research in Ethiopia (1969-2019): Systematic analysis

The objective of this paper was to systematically analyze the trend of plant ecological research in Ethiopia. The inclusion and exclusion of the articles for analysis were performed using Reporting Standards for Systematic Evidence Syntheses (ROSES) flow diagram developed for systematic review/meta-analysis. The number of articles published, authors, and collaboration has increased dramatically since the 1960s. Most of the research largely focused on the Dry evergreen Afromontane Forest and grassland complex (DAF) and Moist evergreen Afromontane Forest (MAF) vegetation types, comprising of about 52.6%. Of the remaining vegetation types, the woodlands (14.3%) i.e. Acacia-Commiphora woodland and bushland proper (ACW), and Combretum-Terminalia woodland and wooded grassland (CTW), desert and semi-desert scrubland (DSS) (2.3%), and the Afroalpine (AA) and Ericaceous Belt (EB) (1.5%) received little attention. A descriptive study on plant community ecology revolving on floristic composition and community structure is the dominant research theme, which revealed a narrow theme in contrast to the global trend. Other plant ecological studies such as reproductive and dispersal ecology of invasive plant species, and pollination ecology seems largely a neglected topic by the academia. Furthermore, the recommendations forwarded are not result-based. As a future direction, the Ethiopian government should develop a project database both for completed and ongoing projects.

ecology↗

bioRxiv2020

The genotypic and genetic diversity of enset (Ensete ventricosum) landraces used in traditional medicine is similar to the diversity found in starchy landraces

BackgroundEnset (Ensete ventricosum) is a multipurpose crop extensively cultivated in southern and southwestern Ethiopia for human food, animal feed and fiber. It contributes to the food security and rural livelihoods of 20 million people. Several distinct enset landraces are cultivated for their uses in traditional medicine. Socio-economic changes and the loss of indigenous knowledge might lead to the decline of important medicinal landraces and their associated genetic diversity. However, it is currently unknown whether medicinal landraces are genetically differentiated from other landraces. Here, we characterize the genetic diversity of medicinal enset landraces to support effective conservation and utilization of their diversity ResultsWe evaluated the genetic diversity of 51 enset landraces of which 38 have reported medicinal value. A total of 38 alleles were detected across the 15 SSR loci. AMOVA revealed that 97.6% of the total genetic variation is among individual with an FST of 0.024 between medicinal and non-medicinal landraces. A neighbor-joining tree showed four separate clusters with no correlation to the use values of the landraces. Principal coordinate analysis also confirmed the absence of distinct clustering between the groups, showing low differentiation among landraces used in traditional medicine and those having other use values. ConclusionWe found that enset landraces were clustered irrespective of their use value, showing no evidence for genetic differentiation between enset grown for medicinal uses and non-medicinal landraces. This suggests that enset medicinal properties may be restricted to a more limited number of genotypes, a product of interaction with the environment or management practice, or partly misreported. The study provide baseline information that promotes further investigations in exploiting the medicinal value of these specific landraces

genetics↗

bioRxiv2020

Germination ecology of wild and domesticated Ensete ventricosum: Evidence for maintenance of sexual reproductive capacity in a vegetatively propagated perennial crop

O_LILoss of sexual reproductive capacity has been proposed as a syndrome of domestication in vegetatively propagated crops, but there are relatively few examples from agricultural systems. In this study we compare sexual reproductive capacity in wild (sexual) and domesticated (vegetative) populations of enset (Ensete ventricosum (Welw.) Cheesman), a tropical banana relative and Ethiopian food security crop. C_LIO_LIWe examined floral and seed morphology and germination ecology across 35 wild and domesticated enset. We surveyed variation in floral and seed traits, including seed weight, viability and internal morphology, and germinated seeds across a range of constant and alternating temperature regimes to characterise optimum germination requirements. C_LIO_LIWe report highly consistent floral allometry, seed viability, internal morphology and days to germination in wild and domesticated enset. However, seeds from domesticated plants responded to cooler temperatures with greater diurnal range. Shifts in germination behaviour appear concordant with a climatic envelope shift in the domesticated distribution. C_LIO_LIOur findings provide evidence that sexual reproductive capacity has been maintained despite long-term near-exclusive vegetative propagation in domesticated enset. Furthermore, certain traits such as germination behaviour and floral morphology, may be under continued selection, presumably through rare sexually reproductive events. Compared to sexually propagated crops banked as seeds, vegetative crop diversity is typically conserved in living collections that are more costly and insecure. Improved understanding of sexual propagation in vegetative crops may have applications in germplasm conservation and plant breeding. C_LI

ecology↗

bioRxiv2019

Micronutrient composition and microbial community analysis across diverse landraces of the Ethiopian orphan crop enset

Enset (Ensete ventricosum) is a major starch staple and food security crop for 20 million people. Despite substantial diversity in morphology, genetics, agronomy and utilization across its range, nutritional characteristics have only been reported in relatively few landraces. Here, we survey nutritional composition in 22 landraces from three enset growing regions. We present mineral characterization of enset corm tissue, free amino acid characterization of raw and processed (fermented) tissues and genomic analysis of the microbial community associated with fermentation. We show that compared to regionally important tubers and cereals, enset is high in calcium, iron, potassium and zinc and low in sodium. We report changes in free amino acid composition due to processing, and establish that the bacteria genera Acetobacter, Lactobacillus and Bifidobacterium, predominate during fermentation. Nutritional and microbial variation presents opportunities to select for improved composition, quality or safety with potentially significant impacts in food security and public health.

plant biology↗