Maintenance and expansion of genetic and trait variation following domestication in a clonal crop.

Clonal propagation enables favourable crop genotypes to be rapidly selected and multiplied. However, the absence of sexual propagation can lead to low genetic diversity and accumulation of deleterious mutations, which may eventually render crops less resilient to pathogens or environmental change. To better understand this trade-off, we characterize the domestication and contemporary genetic diversity of Enset (Ensete ventricosum), an indigenous African relative of bananas (Musa) and a principal starch staple for 20 million Ethiopians. Wild enset reproduction occurs strictly by sexual outcrossing, but for cultivation, it is propagated clonally and associated with diversification and specialization into hundreds of named landraces. We applied tGBS sequencing to generate genome-wide genotypes for 192 accessions from across enset's cultivated distribution, and surveyed 1340 farmers on enset agronomic traits. Overall, reduced heterozygosity in the domesticated lineage was consistent with a domestication bottleneck that retained 37% of wild diversity. However, an excess of putatively deleterious missense mutations at low frequency present as heterozygotes suggested an accumulation of mutational load in clonal domesticated lineages. Our evidence indicates that the major domesticated lineages initially arose through historic sexual recombination associated with a domestication bottleneck, followed by the amplification of favourable genotypes through an extended period of clonal propagation. Among domesticated lineages, we found a significant phylogenetic signal for multiple farmer-identified food, nutrition and disease resistance traits and little evidence of contemporary recombination. The development of future-climate adapted genotypes may require crop breeding, but outcrossing risks exposing deleterious alleles as homozygotes. This trade-off may partly explain the ubiquity and persistence of clonal propagation over recent centuries of comparative climate stability.

Enset in Ethiopia: a poorly characterized but resilient starch staple.

BACKGROUND: Enset (Ensete ventricosum, Musaceae) is an African crop that currently provides the staple food for approx. 20 million Ethiopians. Whilst wild enset grows over much of East and Southern Africa and the genus extends across Asia to China, it has only ever been domesticated in the Ethiopian Highlands. Here, smallholder farmers cultivate hundreds of landraces across diverse climatic and agroecological systems. SCOPE: Enset has several important food security traits. It grows over a relatively wide range of conditions, is somewhat drought-tolerant, and can be harvested at any time of the year, over several years. It provides an important dietary starch source, as well as fibres, medicines, animal fodder, roofing and packaging. It stabilizes soils and microclimates and has significant cultural importance. In contrast to the other cultivated species in the family Musaceae (banana), enset has received relatively little research attention. Here, we review and critically evaluate existing research, outline available genomic and germplasm resources, aspects of pathology, and explore avenues for crop development. CONCLUSION: Enset is an underexploited starch crop with significant potential in Ethiopia and beyond. Research is lacking in several key areas: empirical studies on the efficacy of current agronomic practices, the genetic diversity of landraces, approaches to systematic breeding, characterization of existing and emerging diseases, adaptability to new ranges and land-use change, the projected impact of climate change, conservation of crop wild relatives, by-products or co-products or non-starch uses, and the enset microbiome. We also highlight the limited availability of enset germplasm in living collections and seedbanks, and the lack of knowledge of reproductive and germination biology needed to underpin future breeding. By reviewing the current state of the art in enset research and identifying gaps and opportunities, we hope to catalyse the development and sustainable exploitation of this neglected starch crop.

Soil seed bank distribution and restoration potential in the vegetation of Buska Mountain range, Hamar district, southwestern Ethiopia.

The seed banks are vital components for the reestablishment of degraded lands since they are used to predict the future coverage of vegetation and allow for the implementation of appropriate conservation measures in a particular area. The study was conducted in the Buska Mountains of the Hamar area in south-western Ethiopia and determined the composition, density and vertical distribution of soil seed banks under various land-use systems and soil layers. A total of 96 soil samples were involved in the study; four land-use types (grassland, forest, scrub and bare ground). Three distinct soil layers from each plot (0-3 cm, 3-6 cm, 6-9 cm depths) were sampled. Jaccard's Similarity Coefficient was applied to evaluate the correspondence between different land-use types and soil layers. One-way ANOVA was used to compute species density and composition respectively within land-use systems along with the seed bank and above ground vegetation. Fifty six (56) species within 27 plant families and 50 genera were recorded. Twenty percent of the species was contributed by Asteraceae followed by Poaceae (16%). Herbaceous growth forms were the most dominant in the area, contributing about 78.6%. The total seedling density in the study plots was 8171 seedlings/m2. Jaccard's Similarity Coefficient is relatively higher (0.52) between grassland and scrub, while the forest and bare land had the least amount of similarity (0.22). There was seen a higher similarity of species between the first and second soil layers and a decreasing density with soil depth. A substantial difference between the aboveground species and seed bank was recorded in the area. The lower resemblance between the standing vegetation and the seed bank infers a lower overall restoration potential and suggests other alternative regeneration mechanisms such as seedling plantation of priority indigenous plant species and avoiding anthropogenic disturbances.

Ethnobotanical investigation of medicinal plants in Buska Mountain range, Hamar district, Southwestern Ethiopia.

BACKGROUND: Despite the fact that ethnobotanical studies have been conducted in various parts of Ethiopia, compared with the existence of the multitude and diverse ethnic groups and their associated traditional knowledge, the studies are not comprehensive enough for all the localities and communities in the country. This is also true for the Hamar community of Southwestern Ethiopia, who are totally dependent on plants and plant products for their livelihood. Hence, this investigation was done to identify and record medicine plants and the native wisdom of the community in the area. METHODS: Three hundred twenty six (326) informants were selected from the 12 lowest governmental units (Kebeles) applying Cochran's formula through stratified random sampling technique. From the total informants, 74 (48 males and 26 females) were purposively selected for in-depth discussion. Semi-structured interviews, focus group discussions, guided field walks as well as market surveys were used for data collection. Standard ethnobotanical analytical tools comprising ranking and comparison were used for the analysis. Preference ranking, pair-wise comparison, informant consensus factor, direct matrix ranking, Cultural Significance Index (CSI) and Jaccard's similarity coefficient (JCS) as well as Analysis of Variances (ANOVA), applying SPSS (version 20) were computed. RESULTS: A total of 145 species practical to cure about 72 ailments of livestock and humans were recorded. Families Fabaceae (with 22% of species), Asteraceae (11%), and Lamiaceae (9%) were discovered as the most dominant families in the area. Shrubs contributed the most (40%) to the growth forms followed by herbs (26.5%). Fresh leaves of the plants were parts that are used most frequently in the area. The highest ICF value (0.94) was recorded for reproductive problem categories. There was a relatively very high dependence of the community on plants and plant products together with a hoarded indigenous knowledge in the area that positively correlated with age (r = 0.82). CONCLUSION: The study's findings revealed that Buska Mountain range is a home for highly diverse and most dependable plant species and associated indigenous knowledge. However, because of the realized environmental threats in the area, the conservation efforts of the community should be invigorated and supported in order to sustain the biodiversity in general and the medicinal plant species in particular.