BackgroundPlectranthus edulis (Vatke) Agnew (locally known as Ethiopian dinich or Ethiopian potato) is one of the most economically important edible tuber crops indigenous to Ethiopia. Evaluating the extent of genetic diversity within and among populations is one of the first and most important steps in breeding and conservation measures. Hence, this study was aimed at evaluating the genetic diversity and population structure of this crop using collections from diverse agro-ecologies in Ethiopia.ResultsTwenty polymorphic expressed sequence tag based simple sequence repeat (EST-SSRs) markers were developed for P. edulis based on EST sequences of P. barbatus deposited in the GenBank. These markers were used for genetic diversity analyses of 287 individual plants representing 12 populations, and a total of 128 alleles were identified across the entire loci and populations. Different parameters were used to estimate the genetic diversity within populations; and gene diversity index (GD) ranged from 0.31 to 0.39 with overall mean of 0.35. Hierarchical analysis of molecular variance (AMOVA) showed significant but low population differentiation with only 3% of the total variation accounted for variation among populations. Likewise, cluster and STRUCTURE analyses did not group the populations into sharply distinct clusters, which could be attributed to historical and contemporary gene flow and the reproductive biology of the crop.ConclusionsThese newly developed EST-SSR markers are highly polymorphic within P. edulis and hence are valuable genetic tools that can be used to evaluate the extent of genetic diversity and population structure of not only P. edulis but also various other species within the Lamiaceae family. Among the 12 populations studied, populations collected from Wenbera, Awi and Wolaita showed a higher genetic diversity as compared to other populations, and hence these areas can be considered as hot spots for in-situ conservation as well as for identification of genotypes that can be used in breeding programs.Electronic supplementary materialThe online version of this article (10.1186/s12863-018-0682-z) contains supplementary material, which is available to authorized users.

Ethiopia is the center of origin and genetic diversity of arabica coffee. Forty-two commercial arabica coffee varieties were developed by Jimma Agricultural Research Center (JARC) of Ethiopian Institute of Agricultural Research (EIAR) and released for production under diverse agro-ecologies of the country. Information on the level of genetic diversity among these varieties is scarce. Out of the 42 varieties, the genetic diversity of 40 widely cultivated commercial varieties was assessed using 14 simple sequence repeat (SSR) markers. These markers revealed polymorphism among the varieties. High average number of polymorphic alleles (7.5) and polymorphic information content (PIC = 80%) per locus were detected among the varieties. The genetic similarity among varieties using the Jaccard's similarity coefficient ranged from 0.14 to 0.78, with a mean of 0.38. The range of genetic similarity coefficient values in 92% of the possible pair-wise combinations varied from 0.14 to 0.50, indicating the presence of distant genetic relatedness among the varieties. Unweighted pair group method using arithmetic mean (UPGMA) clustering showed six major clusters and three singletons. Coffee varieties, belonging to the same geographic origin, were distributed across clusters. This study represents the first evidence of the presence of a high level of genetic diversity in Ethiopian commercial arabica coffee varieties. Divergent varieties with complementing traits could be crossed to develop productive hybrid coffee varieties.

Tef [Eragrostis tef (Zucc.) Trotter] is a staple food crop in Ethiopia, and has become known globally as a health food for its gluten‐free flour, which also has a unique nutritional profile. A key to successful variety development through designed breeding is the use of diverse genetic resources, especially when breeding for complex traits such as tolerance to drought stress. The objective of this study was to assess the response of genetically diverse populations of tef genotypes for yield and yield components, with special emphasis on drought‐stress tolerance, to select promising parents for breeding. One hundred forty‐four tef genotypes were evaluated, involving four experiments representing optimum moisture and drought‐stressed environments. Data from the non‐stressed and drought‐stressed environments were subjected to multivariate analysis, including principal component analysis (PCA) and cluster analysis. Days‐to‐maturity, plant height, panicle length, and panicle seed weight were positively correlated with grain yield in non‐stressed conditions, while these traits had negative correlations with grain yield under drought‐stressed conditions. The genotypes DZ‐Cr‐387, DZ‐01‐787, DZ‐01‐3186, 9432, 9403, 9415, 205917, 205896, 215678, 213237, Jano, Kaye‐Agachew, Purpurea, Kaye‐Murri, and Dschanger were selected as promising parents with superior grain yields, low levels of lodging, tall plant height and long panicles in a non‐stressed environment. Conversely, the genotypes DZ‐Cr‐385, DZ‐Cr‐37, HO‐Cr‐136, DZ‐01‐2053, Dabbi, 207832, Zagure, and Shawa‐Gemerra were selected as superior parents for their early maturity and good yield performances under drought stress.

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Eleusine coracana (L.) Gaertn., commonly known as finger millet, is a multipurpose crop used for food and feed. Genomic tools are required for the characterization of crop gene pools and their genomics-led breeding. High-throughput sequencing-based characterization of finger millet germplasm representing diverse agro-ecologies was considered an effective method for determining its genetic diversity, thereby suggesting potential candidates for breeding. In this study, the genotyping-by-sequencing (GBS) method was used to simultaneously identify novel single nucleotide polymorphism (SNP) markers and genotype 288 finger millet accessions collected from Ethiopia and Zimbabwe. The accessions were characterized at individual and group levels using 5,226 bi-allelic SNPs, with a minimum allele frequency (MAF) of above 0.05, distributed across 2,500 scaffolds of the finger millet reference genome. The polymorphism information content (PIC) of the SNPs was 0.23 on average, and a quarter of them have PIC values over 0.32, making them highly informative. The grouping of the 288 accessions into seven populations based on geographic proximity and the potential for germplasm exchange revealed a narrow range of observed heterozygosity (Ho; 0.09–0.11) and expected heterozygosity (He) that ranged over twofold, from 0.11 to 0.26. Alleles unique to the different groups were also identified, which merit further investigation for their potential association with desirable traits. The analysis of molecular variance (AMOVA) revealed a highly significant genetic differentiation among groups of accessions classified based on the geographic region, country of origin, days to flowering, panicle type, and Al tolerance (p < 0.01). The high genetic differentiation between Ethiopian and Zimbabwean accessions was evident in the AMOVA, cluster, principal coordinate, and population structure analyses. The level of genetic diversity of finger millet accessions varies moderately among locations within Ethiopia, with accessions from the northern region having the lowest level. In the neighbor-joining cluster analysis, most of the improved cultivars included in this study were closely clustered, probably because they were developed using genetically less diverse germplasm and/or selected for similar traits, such as grain yield. The recombination of alleles via crossbreeding genetically distinct accessions from different regions of the two countries can potentially lead to the development of superior cultivars.

Genetic diversity assessment of genetic resources maintained at Gene-Banks has important implication for future improvement, conservation and collection activities. However, such information is not available for sesame collected by IBC, Ethiopia. Inter simple sequence repeat (ISSR) marker was used to assess the level of genetic diversity, genetic structure and genetic distance, and to indirectly estimate the level of gene flow among populations of sesame in Ethiopia. A total of 120 (82 Ethiopian and 38 exotic) sesame accessions and six ISSR primers were used. DNA was extracted using a triple CTAB extraction method from silica gel dried bulked sample of five randomly selected individual plants per accession at the stage of three to four weeks after planting. The presence of higher polymorphism was revealed among accessions collected from Ethiopia (75.85) than the exotic accessions (65.52). The average gene diversity relative to the overall population was 0.24. Samples from Welega was the most diverse, with gene diversity value of 0.26 followed by samples from Tigray (0.20) and Shewa (0.20). Samples from Gojam (0.10) and Sudan (0.12) were the least diverse. Inter-population genetic distance (D) ranged from 0.031 to 0.165 for the overall population. From the exotic accession, samples of South East Asia are distantly related to most of the Ethiopian accessions. Unweighted pair group method with arithmetic mean analysis (UPGMA) of Ethiopian sesame populations revealed two major groups and three outliers (Cultivated, Welega and Illubabore).

Lepidium sativum L. (family Brassicaceae), is an underutilized medicinal plant with worldwide distribution. In Ethiopia, L. sativum occurs in all regions and agro-ecologies at different altitudinal ranges. The study was conducted to assess the genetic diversity of L. sativum population from Ethiopia using inter simple sequence repeat (ISSR) marker. Molecular data generated from ISSR bands recorded was used for computing gene diversity, percent polymorphism and Shannon diversity index and AMOVA. Moreover, the ISSR data was used to construct unweighted pair group method with arithmetic mean (UPGMA) and principal coordinated analysis (PCO) plot using Jaccard's coefficient. Tigray and Amhara population showed higher gene diversity (0.24) and Shannon information index (0.35). All UPGMA, neighbor-joining (NJ) and PCO analysis showed very weak grouping among individuals collected from the same regions. Generally, Tigray and Amhara regions showed moderate to high diversity in ISSR analysis. Different geographical regions of Ethiopia, showed different level of variation; thus conservation priority should be given for those regions that have high genetic diversity. This result also indicates the presence of genetic diversity that can be exploited to improve the productivity of L. sativum in Ethiopia.

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