Cassava: constraints to production and the transfer of biotechnology to African laboratories

Knowledge and technology transfer to African institutes is an important objective to help achieve the United Nations Millennium Development Goals. Plant biotechnology in particular enables innovative advances in agriculture and industry, offering new prospects to promote the integration and dissemination of improved crops and their derivatives from developing countries into local markets and the global economy. There is also the need to broaden our knowledge and understanding of cassava as a staple food crop. Cassava (Manihot esculenta Crantz) is a vital source of calories for approximately 500 million people living in developing countries. Unfortunately, it is subject to numerous biotic and abiotic stresses that impact on production, consumption, marketability and also local and country economics. To date, improvements to cassava have been led via conventional plant breeding programmes, but with advances in molecular-assisted breeding and plant biotechnology new tools are being developed to hasten the generation of improved farmer-preferred cultivars. In this review, we report on the current constraints to cassava production and knowledge acquisition in Africa, including a case study discussing the opportunities and challenges of a technology transfer programme established between the Mikocheni Agricultural Research Institute in Tanzania and Europe-based researchers. The establishment of cassava biotechnology platform(s) should promote research capabilities in African institutions and allow scientists autonomy to adapt cassava to suit local agro-ecosystems, ultimately serving to develop a sustainable biotechnology infrastructure in African countrie

Business Process Re-engineering: A Panacea for Reducing Operational Cost in Service Organizations

Organizations in today’s business environment struggle on how to reduce operation cost in order to set prices that can be afforded by many customers while obtaining reasonable profit.  In order to reduce Operational Cost, service organizations have been working hard to identify techniques that facilitate business processes improvement for reduced Operational Cost. In so doing, the global literature indicates that service organizations adopt Business Process Re-engineering technique as a panacea of reducing Operational Cost. Despite a documented potentiality of Business Process Re-engineering technique, there are mixed empirical results, findings and conclusions regarding the effect of Business Process Re-engineering on Operational Cost. Therefore, this paper aimed at assessing and explaining effects of BPR on Operational Cost.The study used cross-sectional survey design to investigate the effect of BPR on Operational Cost. Intensive literature review enabled the construction of structural measurement model, formulation of testable hypotheses and operationalization of constructs. In order to test the model and hypotheses, data were collected from ninety five (95) service organizations in Tanzania. Results of the study reveal that BPR and delivering speed have no direct effects on Operational Cost; they indirectly affect Operational Cost through the mediations of service quality. Therefore, BPR influences first both service quality and delivery speed in affecting Operational Cost of service organizations. It is now recommended that service organizations should use Business Process Re-engineering as panacea of reducing Operational Cost

Business process re-engineering: the technique to improve delivering speed of service industry in Tanzania

Problem statement: Delivering speed is very critical in today’s business environment. In most cases, service organizations and customers are sensitive to time spent at delivering or receiving a service. Therefore, service organizations must change in order to meet this challenge. Overtime, service organizations have worked hard to identify techniques that enhance service delivering speed for improved performance. Business process re-engineering is one of such techniques that improves business processes; including delivering speed. However, despite documented advantages, most organizations are reluctant to adopt the technique. Purpose: The paper aims at determining the effect of business process re-engineering on delivering speed; enabling organizations to appreciate the performance improvement that is associated with the technique. Methodology: The study used cross-sectional survey design to investigate the effect of BPR on delivering speed. In order to undertake the study, intensive literature review was undertaken to operationalize the constructs and to formulate the hypothesis which was tested after the field work. In total ninety five (95) service organizations participated in the study. Results: From the study, it is revealed that BPR significantly and positively improves delivering speed of service organizations. Conclusion: For improved delivering speed, service organizations should adopt BPR technique to improve business processes for provision of delighting services to customers

Molecular characterization of cassava mosaic geminiviruses in Tanzania

Cassava (Manihot esculenta Crantz) is a basic staple food crop in Tanzania. Cassava mosaic disease (CMD) caused by cassava mosaic geminiviruses (CMGs) constitutes a major limiting factor to cassava production in the country. This study was undertaken to characterize the CMGs occurring in Tanzania using molecular techniques and to map their geographical distribution to generate information on which the formulation of control measures can be based. Using Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP) for analysis of CMGs DNA-A genomes, different CMGs were found to be associated with CMD. Higher molecular diversity was observed among East African cassava mosaic viruses (EACMVs) than African cassava mosaic viruses (ACMVs), which was confirmed later by complete nucleotide sequence analysis. In addition to EACMV and ACMV isolates, two isolates of EACMV Cameroon virus (EACMCV) were found in Tanzania. These were confirmed to be strains of EACMCV Cameroon, originally described in Cameroon, West Africa and here named EACMCV- [TZ1] and EACMCV-[TZ7]. They had high (92%) overall DNA-A nucleotide sequence identity and EACMCV-[TZ1] was widespread in the southern part of the country. A subgenomic DNA form of CMG that appeared to be truncated was identified in a CMD-infected cassava plant. It was confirmed upon sequence analysis to be a defect of EACMV DNA-A and had a capacity of attenuating symptoms when coinoculated with wild-type EACMV. In addition, this study revealed for the first time the presence of two novel non-geminivirus single-stranded DNA (ssDNA) sub-genomic molecules associated with CMG infection. They were shown to be dependent on CMG for replication and movement within the plants, confirming their status as satellite molecules named here as satDNA-II and satDNA-III. When present in coinfection with CMGs, they enhance symptoms and can break high levels of resistance in a cassava landrace. Finally a simple, inexpensive technique is described of archiving, transporting and recovering plant DNA for downstream geminivirus characterisation.Thesis (PhD)--University of Pretoria, 2007.Microbiology and Plant PathologyUnrestricte

Identification and Characterization of Cassava Mosaic Begomoviruses in Non-crop Plants from Unguja and Pemba Islands

Cassava mosaic disease caused by cassava mosaic begomoviruses (CMBs) remains one of the major constraints to cassava production since it causes yield losses up to 100%. Researches showed that some of CMBs infecting cassava plants may be coming from non-crop plants. This study intended to identify and characterize CMBs isolated from non-crop plant species in Unguja and Pemba Islands. A total of 108 viral symptomatic and asymptomatic non-crop leaf samples were collected using stratified sampling. DNA was extracted by using CTAB protocol followed by polymerase chain reaction using universal and specific primers for cassava mosaic begomoviruses identification. Results showed that, among eleven samples that were amplified, four were African cassava mosaic viruses (ACMV) and seven were East African cassava mosaic viruses (EACMV). DNA sequencing by Sanger method showed 97–99% similarities with isolates of ACMV and EACMV reported elsewhere in Africa. Using RbcL and MatK plant barcode genes, Datura stramonium, Solanum melongena and Solanum incanum were found associated with ACMV, while Senna occidentalis, Sida acuta and Ricinus communis harboured EACMV. These findings are a key in understanding the epidemiology of cassava mosaic disease and are potential in the development of sustainable management strategies for this disease. Keywords: Begomoviruses, Cassava mosaic disease, East African cassava mosaic virus, Non crop plants

Review and guide to a future naming system of African Bemisia tabaci species

Once a pest has been correctly identified, its genus and species name can provide a link to valuable indications of its ecology, biology and life history that are critical for developing control strategies. Importantly, this link should exist even when the pest was known under other names (synonyms), or was not considered a pest at all (National Research Council, 1968). Many examples have shown that incorrect identification or classification of a pest has led to fruitless searches for biocontrol agents in the native range, incorrect assignments as disease vectors, and costly, yet misdirected, suppression measures. As new approaches for delimiting species based on molecular information become more widely used, the process of correctly identifying a species has become even more complex. Fortunately, we have good systematic frameworks and nomenclatural systems that are able to cope with these challenges. Here we review challenges associated with classification and identification within the Bemisia tabaci (Gennadius) species complex. These pests and the viruses they transmit have emerged in the past few decades as among the most damaging to food and fibre crops globally (Varma & Malathi, 2003; Pimental et al., 2005; Seal et al., 2006), especially in sub‐Saharan Africa (SSA). The systematics of the B. tabaci species group has been a highly debated topic for years (Boykin, 2014). Putative species are indistinguishable morphologically, so other biological data have been collected to investigate the species in the complex. Based on genetic differences (Colvin et al., 2004; Sseruwagi et al., 2005; Boykin et al., 2007; Boykin et al., 2013; Hsieh et al., 2014) and mating incompatibility (Colvin et al., 2004; Liu et al., 2007; Xu et al., 2010), B. tabaci is now recognized as a species complex that consists of at least 34 putative species (Boykin et al., 2012). The rapid discovery of significant species diversity has led to many changes in the informal names used over the last 10 years (Boykin, 2014), creating confusion in the literature

Phylogenetic Diversity of Allspice (Pimenta Dioica) Collections from Tanzania Using Chloroplast (Cp) Rbcl Gene

This research article was published in Heliyon journal, 2023This study aims to investigates the phylogenetic relationship between various collection of Allspice (Pimenta dioica) from Tanzania using cprbcL gene as a DNA barcode. Allspice is an important plant species valued for its economic, medicinal, and cultural uses. The morphological similarities between Allspice and other trees in the Myrtaceae family have led to misidentification, making it crucial to use DNA barcoding to study their evolution history. The molecular phylogeny was conducted using DNA extraction, PCR amplification, and sequencing of the rbcL gene, followed by phylogenetic analysis. The genomic DNA was extract using the CTAB method and the rbcL gene amplified with a forward primer 5’-ATGTCACCACAAACAGAGACTAAAGC-3’ and a reverse primer 5’-GTAAAATCAAGTCCACCRCG-3’. Phylogenetic analysis of Allspice rbcL gene was performed by multiple sequence alignment using MUSCLE 5.1 embedded in Geneious Prime software version 2023.0.1 phylogenetic tree was constructed using the same software. The results showed that DNA specimen amplified at amplicon size of average 560bp with GC content of 44%. BLASTN search resulted into more than 96% similarity to seventeen members of Myrtaceae family namely Eucalyptus torquata (NC_022401), Eucalyptus spathulata (NC_022400), Eucalyptus torquata (KC180794), Eucalyptus spathulata (KC180793), Syzygium polyanthum (OQ355361), Syzygium aromaticum (ON920513), Luma apiculata (KX162972), Eugenia aggregata (OP650216), Eugenia Selloi (MN095411), Myrcianthes pungens (MN095409), Campomanesia xanthocarpa (KY392760), Acca sellowiana (KX289887), Syzygium samarangense (NC_060657), Lophomyrtus bullata (MW214669), Lenwebbia prominens (MW214668), Lenwebbia lasioclade (MW214667), and Syzygium nervosum (NC_053907). In the phylogenetic tree Allspice rbcL gene has a close branch to members of Myrtaceae family. This study concludes that there is high genetic diversity among Allspice collection from Tanzania and between member of the Myrtaceae family. Additionally, this study provides a foundation for future research on the evolutionary history and population genetics of Allspice in Tanzania

A novel East African monopartite begomovirus-betasatellite complex that infects Vernonia amygdalina

The complete genomes of a monopartite begomovirus (genus Begomovirus, family Geminiviridae) and an associated betasatellite found infecting Vernonia amygdalina Delile (family Compositae) in Uganda were cloned and sequenced. Begomoviruses isolated from two samples showed the highest nucleotide sequence identity (73.1% and 73.2%) to an isolate of the monopartite begomovirus tomato leaf curl Vietnam virus, and betasatellites from the same samples exhibited the highest nucleotide sequence identity (67.1% and 68.2%) to vernonia yellow vein Fujian betasatellite. Following the current taxonomic criteria for begomovirus species demarcation, the isolates sequenced here represent a novel begomovirus species. Based on symptoms observed in the field, we propose the name vernonia crinkle virus (VeCrV) for this novel begomovirus and vernonia crinkle betasatellite (VeCrB) for the associated betasatellite. This is the first report of a monopartite begomovirus-betasatellite complex from Uganda

Elevated viral small RNA profiling in cassava cultivars suppress the occurrence of Cassava brown streak disease (CBSD)

This research article was published by Physiological and Molecular Plant Pathology Volume 130, March 2024Cassava brown streak disease (CBSD), caused by cassava brown streak virus (CBSV) and; Ugandan cassava brown streak virus (UCBSV) causes the most destructive cassava disease in Tanzania. Thus, breeders urgently need CBSD-resistant cultivars to combat the impact of this disease, safeguard cassava production, improve the yields and secure food supply for communities reliant on this staple crop. In this study, we used four cassava cultivars; Albert, KBH 2002/135, KBH 2006/026 and Kiroba to explore how viral small interfering RNA (vsiRNAs), an antiviral silencing mechanism, confers CBSD resistance. Cassava plants were inoculated by grafting method using the single infection of CBSV, UCBSV and mixed infection of these viruses (co-infection). Total RNA was extracted from leaves of each cultivar followed by deep sequencing. The result showed that high level of vsiRNAs was produced in inoculated plants, with the most prominent class being 21 and 22 nucleotides. Kiroba produced the highest level of vsiRNA in both CBSV and UCBSV, whereas KBH 2006/026 produced high level of vsiRNA only with UCBSV infections. In contrast to UCBSV, inoculation with CBSV stimulated severe symptoms but relatively low levels of vsiRNA. Co-infection treatment showed a more complex interaction between the host and virus, with variations in the severity and amount of vsiRNA produced. We conclude that resistance to CBSD varies depending on the type of cultivar and virus species, and the occurrence of CBSD is suppressed in plants with elevated vsiRNA. Therefore, a good understanding on the resistance status of parental materials for breeding is recommended to breeders as a basis for improving cassava production

Desmodium mottle virus, the first legumovirus (genus Begomovirus) from East Africa

A novel bipartite legumovirus (genus Begomovirus, family Geminiviridae), that naturally infects the wild leguminous plant Desmodium sp. in Uganda, was molecularly characterized and named Desmodium mottle virus. The highest nucleotide identities for DNA-A, obtained from two field-collected samples, were 79.9% and 80.1% with the legumovirus, soybean mild mottle virus. DNA-B had the highest nucleotide identities (65.4% and 66.4%) with a typical non-legumovirus Old World begomovirus, African cassava mosaic virus. This is the first report of a legumovirus in East Africa and extends the known diversity of begomoviruses found infecting wild plants in this continent