Potential of Malian Landraces in Hybrid Combination

The first possibility of economic hybrid seed production in sorghum has been discussed since the discovery of the genetic-cytoplasmic male-sterility. The greater advantage of hybrids to yields, compared to cultivars, has been demonstrated throughout the world. Hybrids made with local cultivars of Mali used as the male parents and were compared to their parents. Heterosis was observed in all stages of plant growth. Seedling vigour and seedling drought tolerance were emphatically better than the Malian parents. The frequency of landraces with fertility reactions was more frequent than those with maintainer reactions. Significant and positive heterotic effects were recorded for grain yield per panicle and the panicle yield components, seed number and seed weight. However, there was no scope for direct exploitation of the hybrids involving the ATx623 and Malian landrace parents. The typical Caudatum “turtle-back” seed shape was dominant in hybrid combinations with all Malian races. This seed shape renders the grain more difficult to dehull than local cultivars. The grain of hybrids made with guinea parents had a thick brown sub coat with astringent tannins, which was undesirable for food uses

Sorghum anthracnose and sustainable management strategies in West and Central Africa

Anthracnose caused by Colletotrichum graminicola remains the most important foliar disease of sorghum in West and Central Africa. This paper describes the advances made in sorghum anthracnose research that has led to a better understanding of pathogenic and genotypic diversity, epidemiology and importantly disease management strategies. We further highlight how understanding pathogen diversity interplays with the major sustainable anthracnose management strategies such as the use of host plant resistance and crop residue management within the region

Development and Utilisation of Improved WhiteSeeded, Tan-Plant Grain Sorghum Cultivars in Mali

The pedigree breeding method was successfully adopted to develop high yielding, white-seeded, grain sorghum cultivars with other attributes including “tan” plants, sensitivity to photoperiod and excellent adaptation to the Sudanian and Sahelian agro-ecological conditions in Mali. The new cultivars possess an excellent grain quality which added value for processing. The breeding process included crossing of local guinea race cultivars and improved or introduced Caudatum race varieties, selected from F2, F3, F4, F5 and F6 generations, conducting yield and grain quality trials of advanced lines on station and on-farm with farmer participatory selection. Processing quality of the grain was evaluated through measuring the decortication yield of each cultivar using the TADD (Tangential Abrasive Dehuller Device); measuring shelf life of processed flour in bags made of polyethylene for 3 months; manufacturing of new products by partially substituting wheat flour with flour of new sorghum varieties in pastry and biscuits. The study revealed a series of improved lines with "tan" plants, white grain, Guinea race type characterised by a loose panicle, long glumes and a hard grain. The best example of new cultivars N’Tenimissa, was described as the first white, “tan” plant, straw-coloured glume, photoperiod sensitive and high yielding sorghum cultivar with a white endosperm, and a thin pericarp developed in Mali. The cultivar has almost the same decortication yield with already adopted varieties by farmers. Its flour yield is similar to that of local guinea cultivars, and its flour is nearly as white as wheat flour. The analysis of various organoleptic parameters indicated that partially substituting wheat with 20% sorghum flour made the preferred biscuit by consumers prompting the commercial manufacturing of a biscuit called Deliken by the General Alimentation du Mali (GAM). A commercial sorghum supply chain was initiated by linking smallholders producing the new cultivar to a grain trader for selling the grain to the industry. This shows a path for the future in the diversification of uses of a local staple crop, sorghum. It is based on a strong Public-Private Partnership to link smallholders to the commercial supply chain, providing an incentive for farmers to grow new and highly productive cultivars for the development of value-added products

Genic SNP markers and legume synteny reveal candidate genes underlying QTL for Macrophomina phaseolina resistance and maturity in cowpea [Vigna unguiculata (L) Walp.]

<p>Abstract</p> <p>Background</p> <p><it>Macrophomina phaseolina </it>is an emerging and devastating fungal pathogen that causes significant losses in crop production under high temperatures and drought stress. An increasing number of disease incidence reports highlight the wide prevalence of the pathogen around the world and its contribution toward crop yield suppression. In cowpea [<it>Vigna unguiculata </it>(L) Walp.], limited sources of low-level host resistance have been identified, the genetic basis of which is unknown. In this study we report on the identification of strong sources of host resistance to <it>M. phaseolina </it>and the genetic mapping of putative resistance loci on a cowpea genetic map comprised of gene-derived single nucleotide polymorphisms (SNPs) and amplified fragment length polymorphisms (AFLPs).</p> <p>Results</p> <p>Nine quantitative trait loci (QTLs), accounting for between 6.1 and 40.0% of the phenotypic variance (R²), were identified using plant mortality data taken over three years in field experiments and disease severity scores taken from two greenhouse experiments. Based on annotated genic SNPs as well as synteny with soybean (<it>Glycine max</it>) and <it>Medicago truncatula</it>, candidate resistance genes were found within mapped QTL intervals. QTL <it>Mac-2 </it>explained the largest percent R²and was identified in three field and one greenhouse experiments where the QTL peak co-located with a SNP marker derived from a pectin esterase inhibitor encoding gene. Maturity effects on the expression of resistance were indicated by the co-location of <it>Mac-6 </it>and <it>Mac-7 </it>QTLs with maturity-related senescence QTLs <it>Mat-2 </it>and <it>Mat-1</it>, respectively. Homologs of the <it>ELF4 </it>and <it>FLK </it>flowering genes were found in corresponding syntenic soybean regions. Only three <it>Macrophomina </it>resistance QTLs co-located with delayed drought-induced premature senescence QTLs previously mapped in the same population, suggesting that largely different genetic mechanisms mediate cowpea response to drought stress and <it>Macrophomina </it>infection.</p> <p>Conclusion</p> <p>Effective sources of host resistance were identified in this study. QTL mapping and synteny analysis identified genomic loci harboring resistance factors and revealed candidate genes with potential for further functional genomics analysis.</p

Emergence of a Dhfr Mutation Conferring High-Level Drug Resistance in Plasmodium Falciparum Populations from Southwest Uganda

The S108N, C59R, and N51I mutations in the Plasmodium falciparum gene that encodes dihydrofolate reductase, dhfr, confer resistance to pyrimethamine and are common in Africa. However, the I164L mutation, which confers high-level resistance, is rarely seen. We found a 14% prevalence of the I164L mutation among a sample of 51 patients with malaria in Kabale District in southwest Uganda in 2005 and a 4% prevalence among 72 patients with malaria in the neighboring district of Rukungiri during the same year. Surveillance at 6 sites across Uganda during 2002-2004 reported a single case of infection involving an I164L mutant, also in the southwest, suggesting that this is a regional hot spot. The spatial clustering and increasing prevalence of the I164L mutation is indicative of local transmission of the mutant. Targeted surveillance is needed to confirm the extent of the spread of the I164L mutation and to monitor the impact of I164L on the efficacy of antifolates for intermittent preventive treatment of pregnant women and/or infants with falciparum malaria