Genetic diversity is a fundamental input for every plant breeding program, genetic resources conservation, and evolutionary studies. In situ diversity and population genetic structure of eight cultivated sorghum landrace populations were investigated in the center of origin, Ethiopia using seven phenotypic traits and 12 highly polymorphic sorghum SSR markers. In farmers’ fields, DNA samples were collected using Whatman® plant saver card and quantitative phenotypic traits were measured from 160 individual plant samples belonging to the eight populations representing three diverse geographical regions. High diversity was observed among the various populations for the measured phenotypic traits. The 12 SSR loci produced a total of 123 alleles of which 78 (63.41%) were rare (frequency ≤0.05) with an average of 10.25 alleles per polymorphic locus. The polymorphism information content (PIC) was in the range 0.39-0.85 showing the good discriminatory power of the SSR loci used. Average observed heterozygosity and gene diversity across all populations and loci ranged 0.04-0.33 and 0.41-0.87, respectively. Neighbor-joining and STRUCTURE analyses grouped the 160 samples from the eight populations differently. AMOVA showed 54.44% of the variation to be within populations, 32.76% among populations within regions, and 12.8% among the regions of origin. There was high divergence in the total populations (FST = 0.40) indicating low level of gene flow (Nm = 0.38), but high gene flow was also observed in some adjacent populations. The populations from Wello displayed close relationship with remote Gibe and Metekel populations indicating that the variation followed human migration patterns. Implications of the results for sorghum improvement and germplasm conservation are discussed.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-3-212) contains supplementary material, which is available to authorized users.

Sorghum (Sorghum bicolor L. (Moench)) is the third major cereal crop in Ethiopia in terms of area and production next to tef (Eragrostis tef) and maize (Zea mays). It is the major crop in drought stressed lowland areas that cover 66% of the total arable land in the country. Yield stability is one of the setbacks facing plant breeders in developing widely adapted varieties with superior yield. The present study was carried out to investigate the effect of genotype by environment (GxE) on the yield stability of sorghum (Sorghum bicolor) using fifteen genotypes in eight environments (Locations x years combination). There were significant differences among the genotypes, the environments and GxE interactions. Thus, the three types of univariate stability models: Type-1 (CV i and S had strong rank correlation (r=0.97) but both had either very weak or no rank correlation with the rest of the parameters tested. The Sd 2 i had very weak negative correlation with the remaining parameters. Based on the three stability statistics, the different genotypes were classified as stable. To compliment and verify findings of this univariate approach, the GxE which uses a mulivariate approach was used. The multivariate approach (AMMI model) gives a broader inference. Based on the AMMI model, genotypes 2 and 5 were the most stable, although genotypes 1 and 3 had satisfactory levels of yield performance as well as stability. Therefore, these four genotypes with wider adaptation are recommended for sorghum growing dry lowlands of the country.Key Words: AMMI model, Ethiopia, GxE, hybrids, Sorghum bicolor RÉSUMÉLe Sorgho (Sorghum bicolor L. (Moench)) représente la 3 e principale céréale en Ethiopie, en termes de superficie de production, après le Tef (Eragrostis tef) et le maïs (Zea mays). Il est par ailleurs la culture majeure dans les zones de stress due à la sécheresse au sein des basses terres couvrant 66% de la superficie arable totale du pays. La stabilité du rendement constitue l'une des difficultés que rencontrent les agriculteurs dans le développement de variétés largement adaptées et présentant un rendement supérieur. La présente étude était menée dans le but d'établir par investigations l'effet du genotype et de l'environnement (GXE) sur la stabilité du rendement du sorgho (Sorghum bicolor) par l'utilisation de 15 génotypes au sein de huit environnements (sites x combinaisonannées). Il y avait des différences significatives parmi les génotypes, les environnements ainsi que les interactions GXE. Par conséquent, produisant les 3 types de modèles de stabilité à variable unique: Type -1 (CV i et S avait une corrélation négative très faible avec les autres paramètres restants. Se basant sur les 3 statistiques de stabilité; les différents génotypes étaient classifiés comme stables. En vue de pouvoir compléter et vérifier les résultants par cette approche à variable unique, le GXE qui utilise une approche à multi variants a été utilisé. Cette dernière approche (AMMI Model) donne une large ASFAW ADUGNA 84 déduction. Se basant...

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Finger millet is one of the most neglected and underutilized crops worldwide, yet an important food cereal for millions of poor farmers in

Extensive studies of genetic diversity and population structure important for conservation of wild sorghum are yet lacking in Ethiopia, the centre of origin for cultivated sorghum. To assess both genetic diversity and the probability of gene flow between wild and cultivated types, collections of wild Sorghum bicolor were made from regions in Ethiopia where wild and cultivated sorghum coexist. Morphological data were recorded in situ for both quantitative and qualitative characters from 30 populations in five diverse geographical regions and eight agroecologies. High phenotypic diversity was observed among the wild and weedy sorghum populations. The overall standardized Shannon–Weaver diversity index (H′), computed from the frequencies of all qualitative traits, ranged from 0.47 to 0.98 with an average value of 0.76. Moreover, warm semi-arid lowland (SA2) agroecologies, which contain Tigray populations, supported the highest diversity for these traits. Subspecies verticilliflorum and drummondii (the two major subspecies of wild S. bicolor) were observed in diverse habitats throughout northern and central Ethiopia. In some areas, weedy types showed domestication traits including the absence of awns and reduced seed shattering. The existence of morphologically intermediate forms indicates that gene flow between cultivated and wild forms has likely occurred. Deployment of transgenic crop sorghum, therefore, would pose a distinct risk for transgene movement into wild Ethiopian populations.

Natural hybridization between wild/weedy and crop species often results in rare hybrids, which can be more weedy and difficult to control. Moreover, the advent of transgenic crop plants raises questions of biosafety risk assessment on the consequences of rare hybrids with possible fitness enhancing genes on the environment. This study aimed at measuring the fitness components of wild -crop sorghum hybrids for various juvenile survival and adult morphological and fertility characters as part of the risk assessment of transgenic sorghum in Africa where the crop was believed to have first domesticated and serves as the major staple. Out of a pool of hybrids made in 2010 from 23 wild sorghum accessions and two released cultivated sorghum varieties using hand emasculation techniques, seven were selected for the field study of their fitness components in 2011. The study confirmed that crop -wild hybrids of sorghum are fertile. Two approaches were followed (relative fitness and mid-parent heterosis) which showed that most of the hybrids were as fit as their wild parents, and in some cases they showed mid-parent heterosis for the measured traits. The results of this study highlighted a potential risk that hybrids carrying crop genes (including herbicide resistance transgenes) could pose because they could be more weedy than their wild/weedy parents if transgenic sorghum is deployed in regions where the wild and cultivated sorghum populations coexist, such as in Ethiopia and in other parts of Africa.

The experiment was carried out to estimate GEI in sorghum for grain yield using univariate and multivariate statistical approaches based on two sets of performance trials (T1 and T2). While T1 consisted of 15 genotypes and tested in 8 environments, T2 that consisted of 13 genotypes was carried out in 13 environments. Because the combined ANOVA of each trial revealed significant differences among the genotypes, among the environments and GEI, the five univariate stability estimates: CV(i), S(i)(2), W(i)(2), sigma(i)(2), b(i) and Sd(i)(2) were evaluated for ranking the genotypes. There was positive rank-correlation between CVi and S(i)(2) and among W(i)(2), sigma(i)(2), b(i). Sd(i)(2) had significant positive rank-correlation with sigma(i)(2) and bi in T1 but weak rank-correlation with the remaining parameters in both trials. The three types of univariate stability estimates and the only multivariate stability estimate, the AMMI analysis declared genotypes 2 and 5 to be the most stable in T1, but they gave quite unrelated ranking in T2. Because of the lack of correspondence among the tested stability estimates in the two trials, it was difficult to reach a conclusion on producing genotype recommendation based on the univariate statistical approach. However, as GEI has multivariate nature, the multivariate approach is believed to give more robust inference. Hence, some stable genotypes were suggested using the AMMI model for sorghum growing dry lowlands of the country.