Efficiency of SNP and SSR-based analysis of genetic diversity,population structure,and relationships among cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> (L.) Walp.) germplasm from East Africa and IITA inbred lines

The extent of genetic diversity and relatedness of cowpea germplasm from East Africa are poorly understood. A set of 13 microsatellites (SSR) and 151 single nucleotide polymorphisms (SNPs) markers were applied to assess the levels of genetic diversity in a sample of 95 accessions of local cowpea germplasm and inbred lines of Vigna unguiculata. The average genetic diversity (D), as quantified by the expected heterozygosity, was higher for SSR loci (0.52) than for SNPs (0.34). The polymorphic information content was 0.48 for SSR and 0.28 for SNP while the fixation index was 0.095 for SSR and 0.15 for SNPs showing moderate differentiation and high gene flow among cowpea accessions from East African countries. The results of data analysis of both SSR and SNP markers showed similar clustering patterns suggesting a substantial degree of association between origin and genotype. Principal coordinate analysis (PCoA) with SSR and SNP markers showed that accessions were grouped into two and three broad groups across the first two axes, respectively. Our study found that SNP markers were more effective than SSR in determining the genetic relationship among East African local cowpea accessions and IITA inbred lines. Based on this analysis, five local cowpea accessions Tvu-13490, Tvu-6378, Tvu-13448, Tvu-16073, and 2305675 were identified to be tightly clustered sharing several common alleles with the drought tolerant variety Danila when analyzed with SSR and SNP markers. The findings will assist and contribute to future genetic diversity studies aimed at the genetic improvement of local Eastern Africa cowpea accessions for improved overall agronomic performance in general and breeding for drought tolerant in particular.     

Analyses of genetic diversity and population structure of anchote (Coccinia abyssinica (Lam.) Cogn.) using newly developed EST-SSR markers

Anchote (Coccinia abyssinica (Lam.) Cogn.) is a perennial root crop belonging to Cucurbitaceae family. It is endemic to Ethiopia and distributed over wide range of agro-ecologies. For further improvement and efficient conservation of this crop, characterization of its genetic diversity and its pattern of distribution is a vitally important step. Expressed sequence tags-simple sequence repeats (EST-SSRs) markers were developed from publicly available watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] ESTs in the GenBank database. Among those novel markers, eight were polymorphic and subsequently used for genetic diversity and population structure analyses of 30 anchote accessions collected from western Ethiopia. A total of 24 alleles were obtained across the eight polymorphic loci and 30 accessions that revealed moderate level of genetic diversity in this minor crop. Among the eight loci, locus CA_06 was the most informative with six alleles and polymorphic information content (PIC) of 0.76. The accessions showed about threefold variation in terms of genetic diversity, with expected heterozygosity (He) ranging from 0.15 (accession An) to 0.44 (accession Dg). Other accessions with higher genetic diversity include Ar and Gu (He?=?0.43 and 0.41, respectively). Analysis of molecular variance (AMOVA) revealed that the variation within accessions and among accessions accounted for 84.7% and 15.3% of the total variation, respectively. The study revealed low but significant population differentiation in this crop with no clear pattern of population structure. The EST-SSR markers developed in this study are the first of their kind for anchote and can be used for characterization of its wider genetic resources for conservation and breeding purposes.

     

Carbon stock of Banja forest in Banja district,Amhara region,Ethiopia: An implication for climate change mitigation

This study estimates the carbon stock of Banja Forest which is natural and dry Afromontane forest type in Banja District, northwest of Ethiopia. A systematic sampling method was used to identify each sampling point through the Global Positioning System. A total of 63 plots measuring 20 × 20 m were employed to collect tree species and soil data. Losses on ignition and the Walkley–Black method were used to estimate biomass and soil carbon stock, respectively. The carbon stock of trees was estimated using an allometric equation. The results revealed that the total carbon stock of the forest was 639.87 t/ha whereas trees store 406.47 t/ha, litter, herbs, and grasses (LHGs) 2.58 t/ha and soil 230.82 t/ha (up to 30 cm depth). The carbon pools’ carbon stock variation with altitude and slope gradients were not significant (p > 0.05) which was similar to other previous studies. The Banja Forest is a reservoir of high carbon and thus acts as a great sink of the atmospheric carbon. It can be concluded that the Forest plays a role in climate change mitigation. Hence, it should be integrated with reduced emission from deforestation and degradation (REDD⁺) and the clean development mechanism (CDM) of the Kyoto Protocol to catch monetary benefits.     

Furanosesquiterpenes from Commiphora sphaerocarpa and related adulterants of true myrrh

A new furanosesquiterpene, (1E)-8,12-epoxygermacra-1,7,10,11-tetraen-6-one (3), was isolated from the resin of Commiphora sphaerocarpa together with the known compounds curzerenone (1), furanodienone (2), (1E)-3-methoxy-8,12-epoxygermacra-1,7,10,11-tetraen-6-one (4), (1(10)E,2R*,4R*)-2-methoxy-8,12-epoxygermacra- 1(10),7,11-trien-6-one (5), and dihydropyrocurzerenone (6). Hydrodistillates of the resins of C. sphaerocarpa, C. holtziana, C. kataf and C. myrrha were analysed. The identifications were aided by NMR, GC and GC-MS.     

Improving adaptation to drought stress in white pea bean (Phaseolus vulgaris L.): Genotypic effects on grain yield,yield components and pod harvest index

Common bean (Phaseolus vulgaris L.) is the most important food legume crop in Africa and Latin America where rainfall pattern is unpredictable. The objectives were to identify better yielding common bean lines with good canning quality under drought, and to identify traits that could be used as selection criteria for evaluating drought‐tolerant genotypes. In all, 35 advanced lines were developed through single seed descent and evaluated with a standard check under drought and irrigated conditions at two locations over 2 years in Ethiopia. Grain yield (GY), pod number per m², seed number per m² and seed weight decreased by 56%, 47%, 49% and 14%, respectively, under drought stress. Eight genotypes had better yield with good canning quality under drought compared to the check. Moderate to high proportion of genetic effects were observed under drought conditions for GY and yield components compared to genotype × environment effects. Significant positive correlations between GY and pod harvest index (PHI) in drought suggest that PHI could be used as an indirect selection criterion for common bean improvement.     

Genetic diversity of <Emphasis Type="Italic">Guizotia abyssinica</Emphasis> (L. f.) Cass. (Asteraceae) from Ethiopia as revealed by random amplified polymorphic DNA (RAPD)

Genetic diversity of 70 populations of niger (Guizotia abyssinica) representing all its growing regions in Ethiopia was investigated using random amplified polymorphic DNA (RAPD) to reveal the extent of its populations genetic diversity. Ninety-seven percent of the loci studied was revealed to be polymorphic for the whole data set. The within population diversity estimated by Shannon diversity index and Nei gene diversity estimates was revealed to be 0.395 and 0.158, respectively. The extent of genetic variation of populations from major niger producing regions was significantly lower than that of populations from other regions; however, it is distributed regardless of altitude of growth. Genetic differentiation between populations was estimated with Shannon index as G^′ _ST (0.432), Nei’s G _ST (0.242) and AMOVA based F _ST (0.350) and appears to be equivalent to the average values calculated from various RAPD based studies on outcrossing species. Higher proportion of the variation detected by AMOVA resided within populations (64.58%) relative to the amount of variation among populations (35.42%). UPGMA cluster analysis showed that most of the populations were clustered according to their region of origin. However, some populations were genetically distant from the majority and seem to have unique genetic properties. It is concluded that the crop has a wide genetic basis that may be used for the improvement of the species through conventional breeding and/or marker assisted selection. Collection of germplasm from areas not yet covered and/or underrepresented is the opportunity to broaden the genetic basis of genebank collection.     

Evaluation of multi-satellite precipitation products for soil loss and sediment export modeling over eastern regions of the Koshi River Basin,Nepal

Journal of Soils and Sediments - Precipitation data are an important input variable for soil loss (SL) and sediment export (SE) modeling, although they are rarely available at fine spatial and...