Genetic studies and a search for molecular markers that are linked to Striga asiatica resistance in sorghum

Sorghum [Sorghum bicolor (L.) Moench] is important both as a food and feed crop in Zimbabwe. Its yield losses can be up to 100% when the crop is heavily infested by witchweeds [Striga asiatica (L.) Kuntze]. Witchweed resistant cultivars offer the most practical control option under smallholder (SH) farmer conditions and could become part of a sustainable integrated control strategy. Development of S. asiatica resistant cultivars by conventional breeding is slow and has been hampered by the lack of efficient and reliable screening techniques in breeding programs. Molecular markers that are linked to witchweed resistance can expedite the development of resistant cultivars through adoption of appropriate markerassisted selection (MAS) strategies. The objectives of this investigation were to study the inheritance or low germination stimulant (lgs) production in cultivar SAR 29 and to identify molecular markers that are linked to this trait. Low germination stimulant production is one of the recognised mechanisms of witchweed resistance. A segregating F2 population derived from crosses between cultivars SV-1 (high germination stimulant producer, Striga-susceptible) and SAR 29 (low germination stimulant producer, Striga-resistant) was used for this purpose. Parental and F2 genotypes were screened for lgs production using the agar gel technique (AGT). Maximum germination distance (MGD) was used as the index ofresistance. Deoxyribonucleic acid was extracted from agar gel-screened F2s, and DNA bulks were createdfrom 16 resistant (MGD<10 mm) and 25  extremely susceptible (MGD>25 mm) progeny. Bulked segregantanalysis (BSA) was done using random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers. Ninety-nine of the primers that were polymorphic between parent genotypes (10 SSR and 89 RAPD) were then used to screen a total of 77 segregating F2 progeny. Linkage analysis was performed using the computer software MAPMAKER 3.0b. Segregation ratios of high to low F2 stimulant producers did not differ significantly (P³0.05) from the expected ratio of 3:1. It was therefore deduced that a single recessive gene controlled lgs production in cultivar SAR 29. No molecular marker was found to be linked to the lgs locus. Instead, linkage analysis resulted in the construction of a molecular marker linkage mapconsisting of 45 markers that were distributed over 13 linkage groups (LGs). The other fifty-four loci, including the locus for lgs production, were completely unlinked and could not be assigned to any linkage group. The LGs consisted of 2-8 markers, identified at a LOD grouping threshold of 4.0. The map spanned a total distance of 494.5 cM, Haldane

The Mae I assay for scoring atrazine resistance is codon-usage dependent in legumes

A research experiment on herbicide atrazine usages as observed out in Zimbabwe.Nine different cowpea varieties were grown and total deoxyribonucleic acid (DNA) isolated from the young leaves. This DNA was used to amplify a 291 base pair fragment that contained codon 264 of the psb A gene. The primers used were designed based on the soybean psb A gene sequence. The 291 base pair fragment was digested with the restriction enzyme Mae I to assay for sensitivity/resistance to atrazine using a published method. When Mae I did not cut the 291 base fragment, the whole gene was amplified by the polymerase chain reaction, cloned into pBSK+ll (Stratagene, CA, USA) and sequenced around codon 264. Codons 263 and 264 were found to be GCA and AGT respectively. UWGCG and BLASTsearchesofthepsbAgenesequences in the databases confirmed that Mae I has a recognition site that overlaps with codons 263 and 264 in some legumes but not in others. The Mae I assay used by Cheung and co-workers is therefore not universal but depends on codon usage in legumes

Dynamical and Thermodynamic Elements of Modeled Climate Change at the East African Margin of Convection

We propose a dynamical interpretation of model projections for an end-of-century wetting in equatorial East Africa. In the current generation of global climate models, increased atmospheric moisture content associated with warming is not the dominant process explaining the increase in rainfall, as the regional circulation is only weakly convergent even during the rainy seasons. Instead, projected wetter future conditions are generally consistent with the El Niño-like trend in tropical Pacific sea surface temperatures in climate models. In addition, a weakening in moisture convergence over the adjacent Congo Basin and Maritime Continent cores of convection results in the weakening of near-surface winds, which increases moisture advection from the Congo Basin core toward the East African margin. Overall confidence in the projections is limited by the significant biases in simulation of the regional climatology and disagreement between observed and modeled tropical Pacific sea surface temperature trends to date

Dérivation du haut appareil urinaire par une sonde JJ: indications et résultatsdansuneétude rétrospective et monocentrique

No Abstrac

Editorial review: Male circumcision, gender and HIV prevention in sub-Saharan Africa: a (social science) research agenda

No Abstract.SAHARA J Vol. 4 (3) 2007: pp. 658-66

The Informal Sector In Francophone Africa: Firm Size, Productivity, And Institutions

This book is a major step towards improving the understanding of the complex reality of informal sector firms in francophone West Africa. It innovates by concentrating on informal firms rather than informal employment (as other studies do), and identifying \u27large informal\u27 sector firms whose sales rival those of large formal-sector firms but operate in ways that are similar to small informal operators. Not only is the regulatory environment facing these two types of informal firms distinct, but policies aimed at improving their productivity need to be differentiated. This study focuses on the urban informal sector in three capital cities: Dakar (Senegal), Cotonou (Benin), and Ouagadougou (Burkina Faso). The study also breaks new ground with an eclectic methodology and primary data collection. Quantitative and qualitative firm-level data were collected involving a unique and fruitful collaboration among academic researchers, government officials, the West African economic and monetary union commission, informal and formal sector business associations, and labor unions. This volume represents the culmination of a long collaboration between the Centre de Recherches Economiques Appliquees (CREA) at the University Cheikh Anta Diop of Dakar and the World Bank

To reach the poor: results from the ISNAR-IFPRI Next Harvest study on genetically modified crops, public research, and policy implications

"Local farming communities throughout the world face productivity constraints, environmental concerns, and diverse nutritional needs. Developing countries address these challenges in a number of ways. One way is public research that produces genetically modified (GM) crops and recognize biotechnology as a part of the solution. To reach these communities, GM crops, after receiving biosafety agreement, must be approved for evaluation under local conditions. However, gaps between approvals in the developed and developing world grow larger, as the process of advancing GM crops in developing countries becomes increasingly difficult. In several countries, only insect resistant cotton has successfully moved from small, confined experimental trials to larger, open trials and to farms. By far, most GM crop approvals have been for commercial products that perform well under tropical conditions. However, complete information on public GM crop research in developing countries has not been assessed. “Will policies and research institutions in the developing world stimulate the safe use of publicly funded GM food crops?” The relatively few GM crops approved from public research, coupled with growing regulatory, biosafety capacity, trade, and political concerns, argue to the contrary. To tackle this issue, we identified and analyzed public research pipelines for GM crops among 16 developing countries and transition economies. Respondents reported 209 genetic transformation events for 46 different crops at the time when the survey was conducted. The pipelines demonstrate scientific progress among publicly funded crop research institutes in participating countries. Information and findings are presented for GM crops nearing final stages of selection. Additional details are provided for the types of genes and traits used, the breadth of genetic resources documented, implications for regulation, and the type of research partnerships employed. Regulations, GM crop approvals, choice of transgene, and policy implications are discussed as they affect this research. Based on these findings, recommendations are presented that would help sustain and increase efficiency of publicly supported research while meeting biosafety requirements. To do so, the study examines results concerning investments and choices made in research, capacity, and policy development for biotechnology. These indicate the risk and potential for GM technologies in developing countries. Policy makers, those funding biotechnology, and other stakeholders can use this information to prioritize investments, consider product advancement, and assess relative magnitude of potential risks, and benefits." Authors' Abstract

A SOM-based analysis of the drivers of the 2015–2017 Western Cape drought in South Africa

The multi-year (2015–2017) drought in the South West of the Western Cape (SWC) caused a severe water shortage in the summer of 2017–2018, with damaging impacts on the local and regional economy, and Cape Town being in the news one of the first major cities to potentially run out of water. Here, we assess the links between the rainfall deficits during the drought and (a) large scale circulation patterns, (b) moisture transport, and (c) convective available potential energy (CAPE). We used self-organising maps (SOM) analysis to classify daily ERA-interim 850 hPa geopotential height for the period 1979–2017 (March–October) into synoptic types. This allowed us to identify the dominant synoptic states over Southern Africa that influence the local climate in the area affected by the drought. The results show that (a) the frequency of nodes with rain-bearing circulation types decreased during the drought; (b) the amount of rain falling on days that did have rain-bearing circulation types was reduced, especially in the shoulder seasons (March–May and August–October); (c) the rainfall reduction was also associated with anomalously low moisture transport, and convective energy (CAPE), over SWC. These results add to the existing knowledge of drivers of the Cape Town drought, providing an understanding of underlying synoptic processes