African Orphan Crops under Abiotic Stresses: Challenges and Opportunities

A changing climate, a growing world population, and a reduction in arable land devoted to food production are all problems facing the world food security. The development of crops that can yield under uncertain and extreme climatic and soil growing conditions can play a key role in mitigating these problems. Major crops such as maize, rice, and wheat are responsible for a large proportion of global food production but many understudied crops (commonly known as “orphan crops”) including millets, cassava, and cowpea feed millions of people in Asia, Africa, and South America and are already adapted to the local environments in which they are grown. The application of modern genetic and genomic tools to the breeding of these crops can provide enormous opportunities for ensuring world food security but is only in its infancy. In this review, the diversity and types of understudied crops will be introduced, and the beneficial traits of these crops as well as their role in the socioeconomics of Africa will be discussed. In addition, the response of orphan crops to diverse types of abiotic stresses is investigated. A review of the current tools and their application to the breeding of enhanced orphan crops will also be described. Finally, few examples of global efforts on tackling major abiotic constraints in Africa are presented

Drought Adaptation in Millets

Millets are major food and feed sources in the developing world especially in the semi-arid tropical regions of Africa and Asia. The most widely cultivated millets are pearl millet [Pennisetum glaucum (L.) R. Br.], finger millet [Eleusine coracana (L.) Gaertn], foxtail millet [Setaria italica (L.) P. Beauvois], Japanese barnyard millet [Echinochloa esculneta (A. Braun) H. Scholz], Indian Barnyard millet [Echinochloa frumetacea Link], kodo millet [Paspalum scrobiculatum L.], little millet [Panicum sumatrense Roth.ex.Roem. & Schult.], proso millet [Panicum miliaceum L.], tef [Eragrostis tef (Zucc.) Trotter] and fonio or acha [Digitaria exilis (Kippist) Stapf and D. iburua Stapf]. Millets are resilient to extreme environmental conditions especially to inadequate moisture and are rich in nutrients. Millets are also considered to be a healthy food, mainly due to the lack of gluten (a substance that causes coeliac disease) in their grain. Despite these agronomic, nutritional and health-related benefits, millets produce very low yield compared to major cereals such as wheat and rice. This extremely low productivity is related to the challenging environment in which they are extensively cultivated and to the little research investment in these crops. Recently, several national and international initiatives have begun to support the improvement of diverse millet types

Slime cells on the surface of Eragrostis seeds maintain a level of moisture around the grain to enhance germination

Eragrostis is a cosmopolitan genus of the family Poaceae. Several wild species, including E. pilosa (L.) Beauv., are harvested for food, but the only cultivated crop-species is tef [E. tef (Zucc.) Trotter]. Despite its importance as a staple food and its plasticity to diverse environmental conditions, little is known about the structural and physiological strategies that adapt tef seeds to endure diverse and variable moisture regimes. Here, we report the presence of slime cells, a type of modified epidermal cell, covering the fruit of tef and its wild relative, E. pilosa. The slime produced by Eragrostis belongs to the ‘true' slime type, since it is exclusively composed of pectins. Pectin forms uniform layers on the cell wall inner surface, which are confined by a thin cellulose layer to prevent release into the cell lumen. In the presence of water, pectins quickly hydrate, causing swelling of the slime cells. This is followed by their detachment, which may be controlled by a thin cuticle layer on the fruit surface. The ability of slime to absorb and maintain moisture around the grain is thought to be an adaptive feature for Eragrostis growing in dry habitats. This retention of water by slime may create conditions that are suitable for rapid germinatio

Restriction Site Associated DNA Sequencing based Single Nucleotide Polymorphism Discovery in Selected Tef (Eragrostis tef) and Wild Eragrostis Species

አህፅሮት ጤፍ በኢትዮጵያ የተገኘ እና በኢትዮጵያዊያን አርሶአደሮች ለብዙ አመታት ሲመረት የኖረ ዘርፈ ብዙ ጥቅሞች ያሉት የሰብል አይነት ነዉ፡፡ ጤፍ የሚመረተውና ጥቅም ላይ የሚውለው በአብዛኛው በኢትዮጵያ በመሆኑ በአለም አቀፍ ደረጃ ጤፍ ላይ የሚደረጉ ምርምሮች ውሱን ናቸው፡፡  በተለይ የጤፍን ምርምር ለማሳለጥ የተዘጋጁ የሞለኪውላር ሳይንስ ግብአቶች ውሱን በመሆናቸው በሌሎች ሰብሎች ላይ ጥቅም ላይ የዋሉ የዲ ኤን ኤ ሲኩዌንሲንግ ቴክኖሎጂን መሰረት ያደረጉ የምርምር አቅጣጫዎችን መከተል ወሳኝ ነው፡፡  እዚህ በቀረበው  የምርምር ስራ የዲ ኤን ኤ ሲኩዌንሲንግ ቴክኖሎጂን መሰረት ያደረገን የምርምር ስልት በመከተል ከአገሪቱ የተለያዩ አካባቢዎች የተሰበሰቡ አርባ ሁለት የጤፍ ዝርያዎች፡ አንድ ሚውታንት ላይን እና ሁለት ለጤፍ ቅርብ የሆኑ ዋይልድ ሬላቲቭስ ላይ ጥናት ተደርጎ የጤፍን ምርምር በዘመናዊ መልኩ የሚያግዙ ግብአቶች ተገኝተዋል፡፡ Abstract Genome-wide knowledge about the nature and extent of genetic diversity present in tef (Eragrostis tef), the most consumed food grain in Ethiopia is limited. Adopting next generation sequencing (NGS) protocols to enhance its genomics and breeding is essential. Here, we applied the Restriction Site Associated DNA (RAD) sequencing protocol and surveyed the genomes of 43 tef landraces, one mutant line and two wild Eragrostis species. After mapping sequencing reads to the de novo assembled unitag and the tef reference genome, a total of 9,024 and 58,735 high quality single nucleotide polymorphisms (SNPs) were identified, respectively. We identified greater number of SNPs and greater nucleotide diversity in the two wild Eragrostis species than in the tef landraces. The tef landrace populations in this study were poorly differentiated with FST values of 0.015. In the phylogenetic analysis, grouping of the landraces was not consistent with the area of collection, but few localized grouping of the landraces was evident, probably showing the communality of tef seed use across geographical boundaries. The improved tef varieties show reduced genetic diversity compared to the landraces and were all grouped into one cluster reflecting the nature of tef breeding which largely targets common genomic regions. We suggest that future work needs to aim beyond common genomic regions. The work presented here is a valuable addition to the growing molecular resources developed for tef genetic improvement

Genotype by Environment Interaction and Yield Stability of Drought Tolerant Mung Bean [Vigna radiata (L.) Wilczek] Genotypes in Ethiopia

A multi-environment evaluation of mung bean genotypes was conducted in six environments across Ethiopia to select promising genotypes. This study was conducted to estimate the magnitude of genotypes by environment interaction (GEI) and seed yield stability of the selected drought-tolerant mung bean genotypes across different environments. A total of fifteen mung bean genotypes were used. Out of these, two released varieties were used as standard checks. The field experiments were conducted during the 2019 main cropping season at six locations namely Humbo, Gofa, Melkassa, Konso, Jinka, and Kako using a randomized complete block design with three replications. Data were subjected to analysis of variance, Additive Main Effects and Multiplicative Interaction (AMMI), and GGE bi-plot analysis. A combined analysis of variance revealed significant variations among the genotype, environments, and GEI for yield and yield-related traits, indicating that seed yield was significantly affected by these factors. Analysis of variance from the AMMI model indicated the contribution of environment, genotype, and GEI was 59.6%, 16.8%, and 14.8% of the total variation in seed yield, respectively. Sum squares of the first and the second interaction principal component axis (IPCA) explained 47.4% and 7.4% of the GEI variation, respectively. The IPCA1 mean square was highly significant (P≤0.01) and that of IPCA2 was significant (p≤0.05), indicating the adequacy of the AMMI model with the first two IPCAs for cross-validation of the seed yield variation. The magnitude of the GEI sum squares was 4.4 times that of the genotypes sum squares for seed yield, indicating the presence of substantial differences in genotypic responses across the environments. The results for the AMMI, Yield stability index (YSI), AMMI Stability Value (ASV), and GGE biplot, analyses depicted that the genotypes G6 (NLLP-MGC-24), G13 (Acc006), and G3 (NLLP-MGC-15) were identified as stable and high yielders across the environments and should be considered for variety release. AMMI1 biplot showed Kako was the potential and favorable environment for mung bean production, while Humbo was an unfavorable for mung bean production

In-vitro evaluation of mung bean (Vigna radiata L., Wilczek) genotypes for drought tolerance and productivity

Drought stress is the most important factor that limits mung bean production and productivity at large in drought-prone areas of Ethiopia. It is hence necessary to identify and verify drought-tolerant and productive varieties of major crops grown in drought areas of the country like mung bean. The present study was conducted to evaluate mung bean genotypes for drought tolerance under in-vitro conditions and to assess the performance of the in-vitro developed regenerants under greenhouse conditions. The in-vitro experiment was thus arranged in a factorial experiment using a completely randomized design with three replications. Three mung bean genotypes, NLLP-MGC-06/G6 (tolerant), VC6368 (46-40-4)/G34 (moderate), and NLLP-MGC-02/G2 (sensitive) and five polyethylene glycol (PEG) levels (0, 0.5, 1.0, 1.5, and 2.0%) were used. The analysis of variance exhibited significant differences among the genotypes for all the studied parameters except the number of roots per shoot. There were significant differences observed among PEG levels for all the studied parameters. Significant genotypes x PEG interactions were observed for all the studied traits except total roots per culture and survival percentage. Increasing polyethylene glycol concentration from 0% to 2.0% in the medium caused a gradual increase in root length from 0.49 cm at 0% PEG to 1.17 cm at 2.0% PEG, respectively. This revealed an adaptive mechanism to the decreased moisture content in the root zones of plants and enhanced increased root length to reach deeper water in the soil. Regenerant from the treatment combinations of G34 (0) exhibited the highest values for the number of primary branches per plant (4.00). Grain yield for the in-vitro regenerated plants evaluated at greenhouse conditions ranged from 552.52 kg ha-1 at the treatment combination of G2 (1) to 996.23 kg ha-1 at the treatment combinations of G6 (0). Most of the regenerants obtained from NLLP-MGC-06/G6 and VC6368 (46-40-4)/G34 showed the best performance under the greenhouse for drought-tolerance under the in-vitro condition, suggesting that the accumulated performance of the tested regenerants under in-vitro conditions was realized under greenhouse conditions. It also indicated that in-vitro culture is an important tool to identify and verify drought-tolerant genotypes and improve desirable agronomical traits. Further study is indeed required to understand the mechanism of drought tolerance for in-vitro-selected somaclones

Agro-Morphological Traits Diversity in Tef [Eragrostis Tef (Zucc.) Trotter] Genotypes from Various Sources

አህፅሮትጤፍ መገኛው በኢትዮጵያ የሆነ ፈርጀ-ብዙ የአመራረት፣ የአመጋገብና የጤና ጠቀሜታ ያለው ሰብል ቢሆንም ምርታማነቱ በተለያዩ ማነቆዎች የተነሳ በሰፊው ከሚመረቱት የብርዕና አገዳ ሰብሎች አንፃር እጅግ ዝቅ ያለ ነው፡፡ ያለንን የጤፍ ዝርያ ብዝሃነት ማጥናት ግን እነኚህን የምርት ማነቆዎች ተቋቁመው የተሻለ ምርት ሊሰጡ የሚችሉ ዝርያዎችን ለመለየት ዕድል ይፈጠራል፡፡ የዚህ ጥናት ዓላማ ከተለያዩ ምንጮች የተገኙ 188 የጤፍ ብዝሃ-ዘሮችን በሆለታና በደብረ ዘይት ምርምር ማዕከል ውስጥ በኮምፕሊቲሊ ረንዶማይዝድ ብሎክ ዲዛይን ዘርቶ በመገምገም ያላቸውን የዝርያ ተለያይነት፣ ብዝሃነትና ስብጥር ምን እንደሚመስል ለማወቅ ነበር፡፡ በዚህ ጥናት መረጃዎችን ለመተንተን የቫሪያንስ፣ የክላስተር እና የፕሪንሲፓል ኮምፖንነት ትንተና ዘዴዎች ሥራ ላይ ውለዋል፡፡ የዚህ ትንተና ውጤት በስብስቦቹ መካከል ከፍተኛ የሆነ የመድረሻ ጊዜ (ፌኖሎጂ)፣ የምርታማነትና የምርት ኮምፖነንት፣ የግሽበት እና የሞርፎሎጂ ባህሪያት ተለያይነት እንዳለ ይጠቁማሉ፡፡ በተጨማሪ የክላስተር ትንተና በጥናቱ ውስጥ የተካተቱ 188 ብዝሃ-ዘሮችን ወደ ስድስት ቦታ ሲመድባቸው፤ 14 ፖፑለሽኖች ደግሞ ወደ አራት ምድብ ከፍሏቿዋል፡፡ እነዚህ ቡድኖች ግን በማህበረሰብ ከቦታ ቦታ ዝውውር የተነሳ የግድ የዘረ-መል ዝምድናንና የአካባቢ ቅርበትን መሰረት ያደረጉ ብቻ ሆነው አልተገኙም፡፡ የዚህ ጥናት ውጤት በአጠቃላይ ወደፊት በጤፍ ምርምር ማሻሻያ ውስጥ ልንጠቀምባቸው የምንችላቸው የብዝሃ-ዘር ተለያይነት እንዳለ ይጠቁማል፡፡ AbstractA total of 188 tef genotypes including 144 pure lines selected from germplasm collection, 35 released varieties, eight breeding lines and their parents were evaluated in three replications at two locations in Ethiopia. The objectives were to assess the magnitude and pattern of phenotypic diversity in tef genotypes obtained from various sources in Ethiopia. Combined analysis of variance revealed highly significant (P < 0.01) differences among genotypes, locations and genotype by environment interaction for all studied traits. Thus, wide ranges of variations were observed for days to heading (40.3 to 60.8 days) and maturity (101 to 122.5 days), plant height (60.7 to 107.1 cm), panicle length (19.5 to 39.5 cm), number of fertile tillers per plant (2.1 to 5.5) and spikelet per panicle (156.7 to 441.7), 1000 kernel weights (20.7 to 33.0 mg), grain yield (3.7 to 7.3 t/ha) and lodging index (44.7 to 79.3%). Cluster analysis revealed six distinct clusters of 188 individual tef genotypes while the 14 populations were grouped into four distinct clusters. In general, existence of sufficient level of genetic variation was revealed for future use in tef improvement

Genetic diversity of seed storage protein in the Ethiopian garden cress (Lepidium sativum L.)

The Ethiopian garden cress (Lepidium sativum L.) is an important crop extensively used as food and medicine. In this study, total seed storage proteins of 112 garden cress genotypes collected from diverse growing regions in Ethiopia were investigated to assess patterns of genetic diversity and relationships. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), a total of 1774 stable protein bands were identified through discontinuous electrophoresis. Of these, 1597 bands were polymorphic. A maximum of 20 protein sub-units in the range of 15 to 75 kDa were observed per genotype. The similarity coefficient among these genotypes ranged from 0.25 to 1.00 with an average genetic dissimilarity of 0.2754. On the basis of Ward Euclidian distance, the genotypes were grouped into five major clusters, the largest one comprised of 62 genotypes (Cluster III) followed by 26 genotypes in Cluster I. Cluster IV and V contained a total of 14 genotypes that were the most distantly related to other groups, and thus can be potentially used as parents for exploitation of heterotic effects in hybrid breeding programs. Our findings using SDS-PAGE profiles revealed no obvious association between geographic region of origin and germplasm clustering. However, the polymorphism and cluster analysis indicated that garden cress genotypes differed greatly in the composition of seed proteins. This shows that protein profiling could be used as a rapid and reliable method for genetic diversity studies. In order to fully explore the protein based genetic diversity in garden cress germplasm, techniques such as 2-D gel electrophoresis are recommended in future studies

Correlation and path coefficient analysis of yield and quality components of garden cress (Lepidium sativum L.) genotypes in Ethiopia

The improvement for a trait of interest can be achieved by both direct and indirect selection of characters that are more heritable and easy to select. The aim of this study was to determine the degree and nature of associations among seed yield and seed quality related characters. One hundred eight garden cress (Lepidium sativum L.) genotypes were evaluated for their yield and seed quality related traits using a Randomized Complete Block Design with two replications at Raare of Haramaya University Research Site (HRS) and Kulumsa farmer field (KFF), Ethiopia during Meher season in 2014/2015. Correlation and path coefficient analysis were carried out to study the character association and contribution, respectively, for fourteen agro-morphological and seed quality traits. Character association analysis among yield and yield contributing characters revealed that most genotypic correlation coefficients were higher than the respective phenotypic correlation coefficients. Both phenotypic and genotypic correlations revealed that the majority of examined traits had highly significant positive correlation except for oil content and oleoresin content. Genotypic path coefficient analysis of harvest index, biomass per plant and grain yield per plant had exerted positive direct effect on grain yield per plot. Hence, the improvement in grain yield is efficient, if the selection is based on biomass per plant, grain yield per plant and harvest index at both locations