Search

The parasitic weed Striga hermonthica hampers the production of sorghum, the most important cereal crop in Eritrea. This weed has a complex mode of infestation that adapts to many hosts and environments, complicating conventional breeding for resistance, which is the only form of crop improvement available to Eritrean breeders, but has failed. This study aimed at improving resistance against this parasite by transferring 5 Striga resistant Quantitative Trait Loci (QTLs) from resistance donor N13 to Striga susceptible Farmer-Preferred Sorghum Variety (FPSV) Hugurtay from Eritrea. The method involved backcrossing using marker-assisted selection (MAS) and evaluation of the best introgressed lines for Striga resistance in artificially infested fields. Foreground selection was performed with up to 11 polymorphic simple sequence repeat (SSR) markers linked to Striga resistance QTLs, while background selection was conducted in the BC 3 F 2 generation with 27 polymorphic unlinked SSR markers to identify the best recovery of the recurrent parent (RP) genetic background. Out of 84 BC 3 F 3 lines, L2P3-B, L1P5-A and L2P5P35 performed best with respect to both grain yield and reduced Striga infestation. These lines were more resistant to Striga than Hugurtay, but less resistant than N13. The three lines yielded twice as much as N13, with Area Under Striga Number Progression Curve (AUSNPC) values on average 18% higher than that of N13 and 38% lower than that of Hugurtay. This suggests that the introgressed QTLs conferred significant Striga resistance and yield advantage to these BC 3 F 3 backcross progenies under Striga pressure. These lines have good potential for future release and demonstrate that when MAS is available to conventional breeders, even in countries with no genotyping facilities, it is a useful tool for enhancement, expediency and precision in crop improvement.

Sorghum is a major food staple in sub-Saharan Africa (SSA), but its production is constrained by the parasitic plant Striga that attaches to the roots of many cereals crops and causes severe stunting and loss of yield. Away from cultivated farmland, wild sorghum accessions grow as weedy plants and have shown remarkable immunity to Striga. We sought to determine the extent of the resistance to Striga in wild sorghum plants. Our screening strategy involved controlled laboratory assays of rhizotrons, where we artificially infected sorghum with Striga, as well as field experiments at three sites, where we grew sorghum with a natural Striga infestation. We tested the resistance response of seven accessions of wild sorghum of the aethiopicum, drummondii, and arundinaceum races against N13, which is a cultivated Striga resistant landrace. The susceptible control was farmer-preferred variety, Ochuti. From the laboratory experiments, we found three wild sorghum accessions (WSA-1, WSE-1, and WSA-2) that had significantly higher resistance than N13. These accessions had the lowest Striga biomass and the fewest and smallest Striga attached to them. Further microscopic and histological analysis of attached Striga haustorium showed that wild sorghum accessions hindered the ingression of Striga haustorium into the host endodermis. In one of the resistant accessions (WSE-1), host and parasite interaction led to the accumulation of large amounts of secondary metabolites that formed a dark coloration at the interphase. Field experiments confirmed the laboratory screening experiments in that these same accessions were found to have resistance against Striga. In the field, wild sorghum had low Area under the Striga Number Progressive curve (AUSNPC), which measures emergence of Striga from a host over time. We concluded that wild sorghum accessions are an important reservoir for Striga resistance that could be used to expand the genetic basis of cultivated sorghum for resistance to the parasite.

The Mara-Serengeti is an ecosystem of immense importance to both Kenya and Tanzania, contributing significantly to the economies of both countries and forming a rich biodiversity reservoir. This ecosystem is among the most threatened ecosystems on the African continent. Increasing human population density and changing lifestyles have escalated demand for ecosystem services including timber and non-timber forest products (NTFPs). These activities have resulted in reduced land productivity and threatened livelihoods. This environmental communication study is aimed at providing a link between effective environmental communication and participatory sustainable natural resource management. It sets out to identify and prioritize natural resource challenges within the Mara region. It subsequently contextualizes the available and effective communication sources and channels to promote participatory approaches to natural resource management in light of several pressures challenging the Mara region. Specific attributes of the community under study are also taken into account in addition to the correlation between the information source and the message.

Protected areas occupy about 27% of Tanzania’s land of 945,000 sq km and contribute 17.5% of its GDP. But who benefits from and pays for the cost of conservation? This study provides insights into these issues based on a survey conducted in the Serengeti ecosystem, involving 20 villages in Serengeti and Loliondo. The results show that villagers received insignificant benefits from conservation compared with the costs they are incurring. Governance of income at the village level was also a major challenge. There was a lack of capacity to handle large amounts of money and little or no planning, transparency, and accountability. It is recommended that income allocation to the communities is increased and external audits of village funds are conducted. Communities should furthermore be allowed to extract resources sustainably in protected areas. Youth should be encouraged to attend higher education and wildlife technical colleges to learn about the values of wildlife. Finally, the governance structures must be improved to make them gender equitable, participatory, transparent, and fully accountable to the communities and all citizens.

The Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA) through its Agrobiodiversity and Biotechnology Programme is enhancing the utilization of biotechnology research and development innovations in Eastern and Central Africa (ECA). We present successes in the application of biotechnology to enhance the productivity of cassava, sweet potato, banana, maize and sorghum in ECA. These products—drought tolerant maize, sorghum resistant to striga, as well as the technology for producing and distributing disease free planting materials of cassava, sweet potato and banana to farmers—are central for the agro-ecological intensification of farming systems in the central African highlands.

Striga hermonthica (Del.) Benth. is the major biotic constraint to sorghum production. Its control is difficult and can only be achieved through integrated management strategies that depend mainly on host plant resistance and enhanced soil fertility. However, breeding for resistance is hampered by the complexity of host parasite interactions and lack of reliable screening methods. The invention of molecular markers has enhanced the effectiveness of breeding for resistance. Five genomic regions (QTLs) with linked markers associated with Striga resistance were mapped in sorghum variety N13 by [10]. In this study, to increase the efficiency of marker-assisted selection (MAS), 27 EST-SSR markers in close association with Striga resistance QTLs were also identified and mapped. Populations of backcross (BC 3 S 4 ) derived from N13 (Striga resistant) X three farmer preferred sorghum cultivars: Tabat, Wad Ahmed and AG-8 (Striga susceptible) were generated. Thirty-one lines (BC 3 S 4 ) with confirmed Striga field resistance were genotyped with foreground and background selection makers. Twenty resistant lines, with two or more major QTLs were selected for regional evaluation. Of these 10 lines were selected and advanced for multi-location testing, together with Wad Ahmed, Tabat, AG-8, N13, SRN39 and IS9830 as checks. Standard variety trials were conducted in Striga sick plots over three seasons (2009-2011) in Sudan, Gezira Research Station, Damazine, Sinnar, and Gedarif. Results revealed that four lines (T1BC 3 S 4 , AG6BC 3 S 4 , AG2BC 3 S 4 and W2BC 3 S 4 ) were Striga resistant and agronomically superior with yields ranging from 180% to 298% higher relative to their recurrent parents. This Striga resistance coupled with superior attributes of the recurrent parent (including very high yield potentials, high grain quality and drought tolerance) will provide adaptation and stability across a wide range of environments. These are the first products of DNA markerassisted selection (MAS) in sorghum released for cultivation by farmers in sub-Saharan Africa.

Sorghum is the world’s fifth most important cereal, in terms of both production and area planted. Striga hermonthica is one of the major constraints of sorghum production globally and particularly so in Eastern Africa. This study aimed at transferring five Striga resistances Quantitative Trait Loci (QTL) located on linkage groups SBI-01, SBI-02, SBI-05 and SBI-06 from a genetically mapped donor source line N13 into a locally adapted farmer preferred variety, IS8193 using Simple Sequence Repeats (SSRs). Nine polymorphic SSR markers were used to identify F1 generations and the subsequent BC1F1 progenies carrying Striga resistance QTL. Sixteen F1 progenies and twelve BC1F1 were found to have incorporated one to three Striga resistances QTL. The twelve BC1F1 lines with Striga resistance QTL were subsequently backcrossed to IS8193 to produce BC2F1 generation for further fore-ground and back-ground selection in the future. This work was conducted during March 2010 to August 2011 at University of Nairobi and at Biosciences eastern and central Africa (BecA)-Nairobi Kenya.