AFLP/SSR mapping of resistance genes to Alectra vogelii in cowpea (Vigna unguiculata l. Walp)

The parasite weed Alectra vogelii (Benth) causes significant yield reduction of cowpea in Africa. To find and map the resistance gene to A. vogelii in cowpea, a F2 population from a cross involving a resistant parent IT81D-994 and a susceptible TVX3236 was screened. Amplified fragment length polymorphism (AFLP) in combination with Single Sequence Repeat (SSR) analysis was used to identify markers that may be linked to the gene Rav3 conferring resistance to A. vogelii in the cowpea cultivar IT81D-994. The analysis of F2 individuals scored for resistance showedthat a single dominant gene conditioned A. vogelii resistance in IT81D-994 with a probability of 30 to 50%. Sixty-six AFLP/SSR markers were identified. Using MAPMAKER, four linkage groups were found. The first group showed 33 markers linked to the susceptible gene. The closest identified marker was 21.4 centimorgans away from the susceptible gene. The primer combination that showed the closest linkage was 809ACG8 (E-ACG 8 + UBC-809). The second group indicated 4 markers linked together while the third and the fourth groups showed 2 markers linkedtogether respectively. No markers were found linked to the resistance gene Rav3 conferring the resistance in the cultivated cowpea cultivar IT81D-994.La plante parasite Alectra vogelii (Benth) provoque une réduction significative du rendement de niébé en Afrique. Pour repérer et cartographier le gène de résistance à A. vogelii, une population F2 issue d’un croisement impliquant le cultivar résistant IT81D-994 et le cultivar sensible TVX3236 a été criblée. La technique Amplified fragment length polymorphism (AFLP) en combinaison avec des Séquences Simples Répétés (SSR) a été utilisée pour identifier les marqueurs qui seraient liés au gène Rav3 qui confère la résistance à A. vogelii chez le cultivar de niébé IT81D- 994. L’analyse des individus F2 montrant une résistance indique qu’un seul gène dominant conditionne la résistance à A. vogelii chez IT81D-994 avec une probabilité de 30 à 50 %. Soixante six marqueurs AFLP/SSR ont été identifiés. A l’aide de MAPMAKER, 4 groupes de liaison ont été trouvés. Le premier groupe montre 33 marqueurs liés au gène sensible. Le marqueur le plus proche identifié est à 21.4 centimorgans du gène sensible. La combinaison d’amorces ayant des liaisons les plus proches était 809ACG8 (E-ACG 8 + UBC-809). Le secondgroupe montre 4 marqueurs liés ensemble tandis que le troisième et le quatrième groupe montrent 2 marqueurs liés entre eux respectivement. Aucun marqueur n’a été trouvé lié au gène Rav3 qui confère la résistance au cultivar de niébé cultivé IT81D-994.Key words: Parasite, weeds, legumes, molecular marker

The Journey to R4D: An institutional history of an Australian Initiative on Food Security in Africa

Internal Revie

Overview

The part of Africa designated as West Africa is made up of 16 countries— Benin, Burkina Faso, Cape Verde, Côte d’Ivoire, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo. Its land area is about 5 million square kilometers, and its population in 2010 was about 290 million. With the exception of Mauritania, these countries are members of the Economic Community of West African States (ECOWAS). The subregion comprises a diversified agricultural base spread over a wide range of agroecological zones with significant potential for improved agricultural productivity. Agriculture is the major source of livelihood for the majority of West Africans. The agricultural sector employs 60 percent of the active labor force but contributes only 35 percent of gross domestic product (GDP). The disparity between contribution to GDP and share of population means that many West African farmers are very poor, producing close to subsistence levels and facing numerous constraints such as droughts, soil acidity, and nutrientdepleted and degraded soils that impinge on agricultural development. The most important foodcrops grown and consumed in West Africa are cereals— sorghum, millet, maize, and rice; roots and tubers—cassava, sweet potatoes, and yams; and legumes—cowpeas and groundnuts. Major cash crops are cocoa, coffee, and cotton..

Summary and conclusions

Climate variability is a reality that is affecting rural livelihoods in West Africa today and presenting a growing challenge in the region, as in many other parts of the African continent and elsewhere. Climate change will have far-reaching consequences for the poor and marginalized groups among which the majority depend on agriculture for their livelihoods and have a lower capacity to adapt. Weather-related crop failures, fishery collapses, and livestock deaths in addition to losses of property are already causing economic losses and undermining food security in West Africa. This situation is likely to become more desperate and to threaten the survival of the majority of poor farmers as global warming continues. Feeding the increasing populations in a subregion with one of the highest rates of population growth in the world requires radical transformation of a largely underdeveloped agriculture over the next four decades. A major challenge is increasing agricultural production among resource-poor farmers without exacerbating environmental problems and simultaneously coping with climate change..

‘Clash of the Titans’: Structure, Diversity & Farmer Decision-making in cocoa Agroforest Development on

agroforests, managed according to farmer’s decisions and with options for deliberately incorporating high value indigenous trees can help fight Poverty and meet Environmental objectives; thus mitigation this ‘clash of the titans’ of sustainable development in sensitive forest margins of Cameroon. In order to better understand the tree integration context and thereby make the process more relevant to farmer needs and sensitive to ecological questions, a study was carried out in some cocoa systems, with three overarching questions: (i) was large-scale integration of fruit and medicinal trees possible? (ii) How do we ensure that, a useful multi-strata structure develops? (iii) How do we balance ecological and socio-economic prerogatives? This anthropocentric, above ground, study evaluated the spatial relationships between fruit and medicinal trees above 5 m in height within cocoa systems and their ‘usefulness ’ to farmers. In total, 6 hectares of non-contiguous, cocoa plantations were sampled. Data comprised of (i) the shortest horizontal inter-tree distances between species, (ii) the height classes frequency and distribution, and (iii) ‘usefulness ’ perception of trees. In carrying out these studies a number of statistically testable assumptions were made. We assumed with farmers that, tree integration would be favoured by, (i) greater variation in shortest horizontal, inter-tree distances; (ii) a 3:1 ratio with respect to fruit, to medicinal/timber/shade trees, of height classes 11-15m and ≥2

Réponse physiologique et productivité des cultures dans un système agroforestier traditionnel : cas du maïs Zea mays L.) associé au karité (Vitellaria paradoxa Gaertn) dans la zone est du Burkina Faso

Physiological answer and productivity of the cultures in a traditional agroforestry system: the case of maize (Zea mays L.) associated with the shea tree (Vitellaria paradoxa Gaertn.) in the east zone of Burkina Faso. This study was focused on the behaviour of maize cultivated in a forest park of shea butter tree. The surfaces under the influence of shading of the two forms of canopy of this species, termed ball and brush, were compared with the zone located outside the shade of the canopy. Soil water content, growth and productivity of maize were evaluated in these zones. Rainfall was higher under the brush canopy than under the ball canopy. The soil water content appeared to be higher under the ball canopy than the brush canopy in August and September, because of the importance of the shading due to the ball canopy, which contributes to reduce transpiration of the crop and evaporation of water from the soil. Soil water matrix potential variation was higher both under the brush canopy and outside the shade of the canopy. Grain and ear yield as well as stem biomass were relatively higher under the brush canopy than the ball canopy. However they were lower under than outside the canopy

Contribution of improved rice varieties to poverty reduction and food security in sub-Saharan Africa

The dissemination of improved rice varieties could contribute significantly to achieving food security and reducing poverty in sub-Saharan Africa (SSA). This study assesses the number of households and individuals lifted out of poverty and food insecurity. Metadata and primary data collected from sixteen countries were analyzed. A positive impact of improved varieties on food security and poverty reduction was observed over the period 2000–2014. In addition, the rate of adoption of these varieties increased over these years and this increase was more significant after the 2008 food crisis. Average income also increased from US$25 capita–1 to US$ 58 capita–1 for NERICA adopters. These trends could be enhanced by addressing production constraints and certified seed bottlenecks