Colletotrichum circinans and Colletotrichum coccodes can be distinguished by DGGE analysis of PCR-amplified 18S rDNA fragments

The rDNA 18S region of Colletotrichum circinans and C. coccodes was amplified by PCR to evaluate this DNA region as a tool for species delineation. PCR amplification of the 18S of both species produced 1.65 Kb long fragments that covered most of the entire 18S rDNA molecule. DGGE analysis of the amplified fragments distinguished C. circinans from C. coccodes isolates. This result provides molecular evidence that supports the current treatment of C. circinans as a species distinct from C. coccodes, in spite of the failure of previous attempts at genetic differentiation of the two species based on RFLP analysis of the rDNA ITS region. Key Words: DGGE; Colletotrichum circinans; Colletotrichum coccodes; molecular differentiation; species delineation. African Jnl Biotechnology Vol.3(3) 2004: 195-19

Assessing vegetable farmer knowledge of diseases and insect pests of vegetable and management practices under tropical conditions

Accepted author version posted online: 22 Jul 2013. Published online: 02 Jun 2014

Harnessing modern biotechnology for tropical tuber crop improvement: Yam (Dioscorea spp.) molecular breeding

Yams (Dioscorea spp.) constitute a staple food crop for over 100 million people in the humid and subhumid tropics. They are polyploid and vegetatively propagated. The Guinea yams, Dioscorea rotundata and D. cayenensis, are the most important yams in West and Central Africa where they are indigenous, while D. alata (referred to as water yam) is the most widely distributed species globally. The genetics of yams is least understood among the major staple food crops due to several biological constraints and research neglect. Research to unravel the apparent complexity of the yam genome will have far-reaching implications for genetic improvement of this important tuber crop. Some progress has been made in recent years in germplasm characterization and the development of molecular markers for genome analysis. A genetic linkage map based on amplified fragment length polymorphism (AFLP) markers has been constructed for Guinea and water yams. These linkage maps were used to scan the genome for quantitative trait loci (QTL) associated with genes conferring resistance to Yam Mosaic Virus (YMV) in D. rotundata and anthracnose (Colletotrichum gloeosporioides) in D. alata. In addition, candidate random amplified polymorphic DNA (RAPD) markers associated with major genes controlling resistance to YMV and anthracnose have been identified that could be used for selection and pyramiding of YMV and anthracnose resistance genes in yam improvement. Also, molecular markers such as RAPDs, AFLPs, and microsatellites or simple sequence repeats (SSRs) have been developed for yam genome analysis. An initial c-DNA library has been constructed in order to develop expressed sequence tags (ESTs) for gene discovery and as a source of additional molecular markers. This paper will review the advances made, discuss the implications for yam genetic improvement and germplasm conservation, and outline the direction for future research. Key words: Genetic mapping, genome analysis, molecular breeding, PCR-based markers, QTLs, resistance genes, yam. African Journal of Biotechnology Vol. 2 (12), pp. 478-485, December 200

Molecular taxonomic, epidemiological and population genetic approaches to understanding yam anthracnose disease

Water yam (Dioscorea alata L.) is the most widely cultivated yam species globally. The major limitation to the profitable and sustainable production of D. alata is its susceptibility to anthracnose disease. The availability of resistant varieties could potentially form the cornerstone of an integrated management strategy for yam anthracnose; however, anthracnose resistance breeding is hampered by the dearth of knowledge on pathogen identity and diversity. Four forms of Colletotrichum are now known to be associated with foliar anthracnose of yam: the slow-growing grey (SGG), the fast-growing salmon (FGS), the fast-growing olive (FGO), and the fast-growing grey (FGG) forms. The close phylogenetic relationship of the first three forms to reference isolates of Colletotrichum gloeosporioides, and the fact that only strains of these forms have been observed to induce typical anthracnose symptoms on D. alata, recently confirmed that C. gloeosporioides is the causal agent of yam anthracnose disease. The FGG form possibly represents a distinct, endophytic, species as indicated by morphological, biological and molecular criteria. Previous research emphasized epidemiology and control but limited progress was made in understanding yam anthracnose disease based on this classical approach. Molecular approaches have started to unravel the systematics and ecology of Colletotrichum strains associated with yam anthracnose, as well the population biology of C. gloeosporioides on yam. Sexual recombination is a likely mechanism contributing to the high genetic diversity of C. gloeosporioides in yam-based cropping systems. Studies have been initiated to understand the mechanisms that generate genetic variation in C. gloeosporioides, and to gain some insight into the biochemistry of the interactions between the pathogen and yam. Our thesis in this article is that integrating traditional and molecular approaches to understanding C. gloeosporioides systematics, epidemiology and population genetics will lead to a much better understanding of yam anthracnose disease, and thus to the development of effective and sustainable control measures. Research successes and challenges are discussed, as well as their implications for future studies on pathogen evolutionary potential, anthracnose resistance breeding, and the deployment of resistance genes. Key words: Anthracnose, Colletotrichum gloeosporioides, Dioscorea spp., molecular markers, molecular systematics, population biology, resistance breeding, yam. African Journal of Biotechnology Vol. 2 (12), pp. 486-496, December 200

Protein and amino acid composition of different quinoa (chenopodium quinoa willd) cultivars grown under field conditions in Ethiopia, Kenya, Uganda, and Zambia

Protein-energy malnutrition (PEM) remains a public health concern in most developing nations. In Africa, PEM can be attributed to monotonous diets based on cereals, roots, and tubers, with little or no protein of animal origin. Diversifying cropping systems to include protein dense pseudo-cereals such as Quinoa (Chenopodium quinoa Willd.) could help provide more protein in the diet of vulnerable populations. Quinoa is a crop with potential for biodiversification because it has a high nutritional value; however, it is underutilized in Africa, and information about the nutritional quality of the grain grown in contrasting environments is limited. Within the framework of FAO’s commemoration of 2013 as the ‘The International Year of the Quinoa’ (IYQ), a Technical Cooperation Programme (TCP) project was developed with some African countries to assess the capacity of quinoa to adapt to different agro-ecological regions and the nutritional quality of the resulting grain. For this study, we evaluated the protein content and amino acid profile of three genotypes of quinoa that had been grown under diverse altitudes, soil, and climate conditions in Ethiopia, Kenya, Uganda, and Zambia. The mean protein content (g/100g) of Kancolla, Titicaca and BBR varieties grown in Africa ranged from 14.33 ±0.20 to 17.61 ±0.55, 14.23 ±0.25 to 16.65 ±0.55, and 13.13 ±0.2 to 16.23 ±0.49, respectively. On the other hand, the protein content (g/100g) of Kancolla, Titicaca, and BBR seeds grown in Peru was 13.80 ±0.10, 17.43 ±0.31, and 17.07 ±0.11, respectively. The Kancolla variety [grown in Ethiopia and Kenya] had a significantly higher protein content than that obtained from Peru [P < 0.001]. Regarding the profile of essential amino acids, Quinoa is essentially richer in methionine than most cereals. Levels of methionine were lower in the seeds grown in Africa compared to those from Peru [P < 0.001]. In terms of environmental influences, the protein content was relatively higher in quinoa seeds grown in high-altitude areas, where soils have a low pH and high nitrogen content. We conclude that Quinoa can be introduced to Africa, especially to high altitudes and warm regions where the soil has a low pH and high nitrogen content. The crop would be ideal for diversifying local diets

Development and Dissemination of Integrated Crop Management (ICM) Technologies for Management of Biotic and Abiotic Stresses affecting Common bean in PABRA

The common bean is sensitive to many biotic and abiotic constraints. To enhance farm productivity, farmers need to have access to and use bean production practices that combine seed of improved varieties as well as integrated soil fertility management (ISFM) and integrated pest and disease management (IPDM) technologies. This poster describes efforts and achievements by the Pan Africa Bean Research Alliance (PABRA) in the development and delivery of IPDM and ISFM technologies to improve bean productivity across sub-Saharan Africa. Over 50 crop management technologies, IPDM (36) and ISFM (23) have been tested on-station and on farm in different PABRA countries, including: pest/disease tolerant varieties, staking techniques for climbing beans, botanical pesticides for storage pests, intercropping, varietal mixtures, pesticide application, organic and inorganic fertilizers, tithonia, manure amendments, N-P-K application, and integrated management options for major diseases, bean stem maggot and bean bruchids. A two-pronged approach was used to increase access to ISFM/IPDM technologies which involved; i) a deliberate promotion and delivery of improved varieties and ICM technologies as a single package, and ii) the harnessing of enabling policies (including input support systems) to deliver ICM technologies to bean farmers. The combined use of new stress tolerant varieties and improved crop management practices led to yield increases of 65% (Ethiopia) to 400% (DR Congo). The two-pronged approach led to the delivery of ICM technologies to 4.9 million farmers during 2009 – 2011. In countries where the approach was either no

Pan Africa Bean Research Alliance Model

The Pan Africa Bean Research Alliance is a consortium of African-owned regional bean networks consisting of National Agricultural Research Systems (NARS) from 28 countries in sub- Saharan Africa, the International Center for Tropical Agriculture (CIAT) and a number of donor organizations. PABRA’s focus is to improve bean productivity, utilization and commercialization for the benefit of the urban and rural poor. The ultimate goal is to enhance food security, income generation and health of poor communities in a gender equitable manner. The regional bean networks are Eastern and Central Africa Bean Research Network (ECABREN) covering 9 countries, Southern Africa Bean Research Network (SABRN), covering 11 countries and the West and Central Africa Bean Research Network (WECABREN), covering 10 countries. ECABREN, SABRN and WECABREN are semi-autonomous and respond to priorities defined by corresponding sub-regional organizations, which are ASARECA, SADC/FANR and CORAF/WECARD, respectively. All networks implement the same log-frame under PABRA. Activities in the PABRA workplan are developed using a bottom-up approach, and build on the outcome of national program planning followed by planning at the regional network level. PABRA facilitates collaborative research within, among and beyond the regional networks. It also provides a forum for building and maintaining linkages to multiple partners. These collaborative linkages are maintained and strengthened through joint priority-setting, planning, agreed division of responsibilities, joint implementation of activities, and joint reporting. Collaboration is based on national members’ interest and on comparative advantage. In this way, research technologies are shared among countries and significantly contribute to scaling up and wider distribution efforts. Through this partnership, PABRA facilitated seed access to 7.5 million farmers between 2003-2008 and about 7 million between 2009-2011