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The present research paper discussed the utilization of plant waste materials such as blast furnace flue dust and sludge as macro pellets and use of these macro pellets in the production of sinter. Wastes addition as pellets to the sinter modifies the productivity of the laboratory grade sinter machine as well as the better mechanical strength of sinter. At the same it also decreases the coke rate for sinter production. The maximum productivity achieved is 5t/m 2 /day at basicity 2.2(super fluxed sinter). Microstructure of the sinter of basicity 2.2 revels that it consists of re-oxidized hematite (Fe 2 O 3 ) and few magnetite (Fe 3 O 4 ) phases with some slag phase of calcium silicate(CaSiO 3 ). X-ray diffraction also confirms the presence of hematite and magnetite as the main constituents of the sinter. Although using these waste made pellets in the sintering process leads to decrease the coke consumption, simultaneously it is used as secondary raw material and at the same time it is eco-friendly also due to recirculation of hazardous wastes. [ABSTRACT FROM AUTHOR]

The nickel base superalloy, supercast 247A gains its appropriate microstructure and high temperature strength through precipitation hardening mechanism. Because of their service conditions, tensile properties of the alloy have strong influence on stability and life of the turbine blades. Tensile fracture mechanisms of the cast and heat treated superalloy were studied in ambient temperature, with a constant strain rate of 0.1 mm per minute. Scanning electron microscopy was used to provide structural and fractography evidence of the nickel base superalloy supercast 247A of different heat treatment conditions. The fractography results of the tensile tested specimens were in good agreement with the variation in alloy ductility. Many fractography features such as transgranular and intergranular fracture with fine dimples, cleaved facets and a combination of them were observed in the specimens tested at different heat treatment temperatures. [ABSTRACT FROM AUTHOR]

Two new ‘legumoviruses’ (genus Begomovirus; family Geminiviridae) naturally infecting soybean ( Glycine max L. Merr.) in Nigeria were molecularly characterized. Based on characteristic symptoms in soybean, the two viruses are provisionally designated as Soybean mild mottle virus (SbMMV) and Soybean chlorotic blotch virus (SbCBV). SbCBV has a bipartite genome, whereas SbMMV has only a DNA A component. The DNA A component of SbMMV is 2,768 nucleotides (nt) long and the DNA A and DNA B components of SbCBV are 2,708 and 2,647 nt long, respectively. In pairwise comparisons, the DNA A component of SbMMV and SbCBV showed 62% nt sequence identity, indicating that these two viruses are distinct. Whereas the DNA A of SbMMV contains two virion- and four complementary-sense open reading frames, that of SbCBV lacks the virus-sense AV2, a signature gene present in ‘Old World’ begomoviruses. A pairwise comparison with the corresponding nucleotide sequence of other begomoviruses in the databases indicated that SbCBV had a maximum of 74% identity with cowpea golden mosaic virus and SbMMV had a maximum of 65% identity with mungbean yellow mosaic India virus and kudzu mosaic virus. Phylogenetic analysis of the DNA A component of SbCBV and SbMMV together with those of other begomoviruses available in the databases showed clustering of the two viruses within the ‘legumovirus’ clade of the begomovirus phylogenetic tree. In addition, the DNA A and B components of SbCBV from Centrosema pubescens Benth were found to be identical to those from soybean, indicating that leguminous wild species are a potential alternative host for the virus. Since soybean is an introduced crop, the identification of two distinct begomoviruses naturally infecting soybean in Nigeria suggests the occurrence of ‘legumoviruses’ in plant species indigenous to Africa and underscores their potential threat to sustainable cultivation of soybean on the African continent. [ABSTRACT FROM AUTHOR]

Examines the identification of Cecidophyopsis mites based on sequence repeats of ribosomal DNA internal transcribed spacer-1 sequences. Use of polymerase chain reaction (PCR); Description of the mites; Assessment on the genetic variability of mites.

Yam (Dioscorea spp.) is a valuable food security crop in West Africa, where 92% of the world production occurs. The availability of quality seed tubers for increased productivity is a major challenge. In this study, minitubers weighing 1, 3, and 5 g produced from virus-free single-node vine cuttings of two improved yam varieties (Asiedu and Kpamyo) growing in an aeroponics system were assessed for suitability in seed production at a population of 100,000 plants ha−1. A 3 × 2 factorial experiment with randomized complete block design and three replications was set up during the cropping seasons of 2017 to 2019 at the International Institute of Tropical Agriculture Research Station in Kubwa, Abuja, Nigeria. Results showed field establishments of 87%–97.8%. Yields differed with minituber size, variety, and cropping season; the highest was 31.2 t ha−1 in 2019 and the lowest, 10 t ha−1 in 2018 from 5 and 1 g Kpamyo minitubers, respectively. The estimated number of tubers produced per hectare by 1, 3, and 5 g minitubers was 101,296, 112,592, and 130,555, with mean weights per stand of 159.2, 187.3, and 249.4 g, respectively. We recommend using less than 6 g minitubers for seed yam production due to their high multiplication rates. [ABSTRACT FROM AUTHOR]

The international collections of plant genetic resources for food and agriculture (PGRFA) hosted by 11 CGIAR Centers are important components of the United Nations Food and Agriculture Organization's global system of conservation and use of PGRFA. They also play an important supportive role in realizing Target 2.5 of the Sustainable Development Goals. This paper analyzes CGIAR genebanks' trends in acquiring and distributing PGRFA over the last 35 years, with a particular focus on the last decade. The paper highlights a number of factors influencing the Centers' acquisition of new PGRFA to include in the international collections, including increased capacity to analyze gaps in those collections and precisely target new collecting missions, availability of financial resources, and the state of international and national access and benefit-sharing laws and phytosanitary regulations. Factors contributing to Centers' distributions of PGRFA included the extent of accession-level information, users' capacity to identify the materials they want, and policies. The genebanks' rates of both acquisition and distribution increased over the last decade. The paper ends on a cautionary note concerning the potential of unresolved tensions regarding access and benefit sharing and digital genomic sequence information to undermine international cooperation to conserve and use PGRFA. [ABSTRACT FROM AUTHOR]

The article discusses the effect of aflatoxin B1 (AFB1) contaminated food on human beings and development of a technique for its detection. As stated, biomarkers in blood, urine, and tissues have been used to monitor the AFB1exposure. It further informs that indirect competitive enzyme linked immunosorbent assay (IC-ELISA) has the potential for epidemiological studies in order to minimize aflatoxin contamination in the AFB1 exposed individuals.

The Global Plant Health Assessment (GPHA) is a collective, volunteer-based effort to assemble expert opinions on plant health and disease impacts on ecosystem services based on published scientific evidence. The GPHA considers a range of forest, agricultural, and urban systems worldwide. These are referred to as (Ecoregion × Plant System), i.e., selected case examples involving keystone plants in given parts of the world. The GPHA focuses on infectious plant diseases and plant pathogens, but encompasses the abiotic (e.g., temperature, drought, and floods) and other biotic (e.g., animal pests and humans) factors associated with plant health. Among the 33 (Ecoregion × Plant System) considered, 18 are assessed as in fair or poor health, and 20 as in declining health. Much of the observed state of plant health and its trends are driven by a combination of forces, including climate change, species invasions, and human management. Healthy plants ensure (i) provisioning (food, fiber, and material), (ii) regulation (climate, atmosphere, water, and soils), and (iii) cultural (recreation, inspiration, and spiritual) ecosystem services. All these roles that plants play are threatened by plant diseases. Nearly none of these three ecosystem services are assessed as improving. Results indicate that the poor state of plant health in sub-Saharan Africa gravely contributes to food insecurity and environmental degradation. Results further call for the need to improve crop health to ensure food security in the most populated parts of the world, such as in South Asia, where the poorest of the poor, the landless farmers, are at the greatest risk. The overview of results generated from this work identifies directions for future research to be championed by a new generation of scientists and revived public extension services. Breakthroughs from science are needed to (i) gather more data on plant health and its consequences, (ii) identify collective actions to manage plant systems, (iii) exploit the phytobiome diversity in breeding programs, (iv) breed for plant genotypes with resilience to biotic and abiotic stresses, and (v) design and implement plant systems involving the diversity required to ensure their adaptation to current and growing challenges, including climate change and pathogen invasions., Competing Interests: The author(s) declare no conflict of interest.

The root-lesion nematodes (RLN), Pratylenchus spp., are among the major plant-parasitic nematodes affecting yam ( Dioscorea spp.) production in West Africa. The distribution and diversity of RLN species associated with yam was investigated through a soil and tuber survey of the main producing areas in Nigeria and Ghana. Pratylenchus spp. were detected in the yam rhizosphere in 59% of 81 soil samples from Ghana and 39% of 114 soil samples from Nigeria. Pratylenchus spp. were detected in 24 of 400 tubers examined, in combination with root-knot nematodes ( Meloidogyne spp.) and their associated damage of galls and crazy roots (79%), and with yam nematode ( Scutellonema bradys ) and their associated damage of dry rot (17%), although no specific additional symptoms were observed for Pratylenchus spp. Species of Pratylenchus were identified by their morphological features and by sequences of the D2-D3 region of the 28 S rDNA gene and the mitochondrial cytochrome oxidase I gene ( COI ). Pratylenchus brachyurus was the most frequent RLN species in both the rhizosphere and tubers of yam. Pratylenchus hexincisus was recovered from one tuber collected in Nigeria. While further investigations are required to establish the host status of yam for this nematode, this appears to be the first record of P. hexincisus on yam. The present taxonomical status of P. scribneri and P. hexincisus is discussed., (© 2020 Authors.)

This study analyzed the genetic diversity of 18 Yam mild mosaic virus (YMMV, genus Potyvirus) isolates collected from field surveys in Ghana (N = 8) and Nigeria (N = 10) in 2012-13. The full coat protein (CP) encoding region of the virus genome was sequenced and used for comparison and phylogenetic analysis of the YMMV isolates available in the NCBI nucleotide database. The mean nucleotide (nt) diversity was 13.4% among the 18 isolates (17 from D. alata and one from D. rotundata ), 11.4% within the isolates of Ghana and 7.4% within the isolates of Nigeria. The phylogenetic clustering of the 18 YMMV isolates did not show correlation with the country of origin, and they aligned with the reference sequences of four of the 11 YMMV monophyletic groups representing the cosmopolitan group and the African group of YMMV isolates. High sequence homology of 99% between the YMMV sequence from Nigeria (CP12-DaN6-1) and a previously reported sequence from Togo (GenBank Accession Number AF548514) suggests a prevalence of seed-borne virus spread within the region. Understanding YMMV sequence diversity in West Africa aid in the improvement of diagnostic assays necessary for virus indexing and seed certification., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Author(s).)

The geographic pattern of cropland is an important risk factor for invasion and saturation by crop-specific pathogens and arthropods. Understanding cropland networks supports smart pest sampling and mitigation strategies. We evaluate global networks of cropland connectivity for key vegetatively propagated crops (banana and plantain, cassava, potato, sweet potato, and yam) important for food security in the tropics. For each crop, potential movement between geographic location pairs was evaluated using a gravity model, with associated uncertainty quantification. The highly linked hub and bridge locations in cropland connectivity risk maps are likely priorities for surveillance and management, and for tracing intraregion movement of pathogens and pests. Important locations are identified beyond those locations that simply have high crop density. Cropland connectivity risk maps provide a new risk component for integration with other factors-such as climatic suitability, genetic resistance, and global trade routes-to inform pest risk assessment and mitigation., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Institute of Biological Sciences.)

Maize yellow mosaic virus (MaYMV; genus Polerovirus ; family Luteoviridae ) was recently characterized from maize in China and subsequently detected in mixed infection with sugarcane mosaic virus (genus Potyvirus ; family Potyviridae ) in sugarcane and itch grass in Nigeria. This study was conducted to understand the status and genetic diversity of MaYMV in maize fields in the northern guinea savannah region of Nigeria. A survey was conducted in 2017 and maize (n = 90) and itch grass (n = 10) plants suspected of virus infection based on appearance of mosaic and/or yellowing symptoms were sampled in Kaduna (n = 65) and Katsina (n = 35) states. The samples were screened individually by reverse transcription polymerase chain reaction using the genus-specific primers targeting poleroviruses and potyviruses Pol-G-F and Pol-G-R primers encompassing the partial P1-P2 fusion protein and coat protein genes of poleroviruses and primer pair CI-For & CI-Rev encompassing the partial cylindrical inclusion proteins of most potyviruses. A subset of amplified DNA fragments was cloned, Sanger-sequenced, and the obtained sequences were bioinformatically analyzed along with corresponding sequences from GenBank. The ~ 1.1 Kb polerovirus fragment was detected in 32.2% (29/90) of the maize samples while all 10 itch grass samples tested negative. BLASTN analysis of sequences derived from six polerovirus samples confirmed the virus identity as MaYMV. In pairwise comparisons, the MaYMV sequences derived in this study shared 97-99% nucleotide identity with sequences of other MaYMV isolates available in the NCBI GenBank. Phylogenetic analysis revealed the segregation of global MaYMV sequences into three host-independent clusters with pattern of geographic structuring., (© Indian Virological Society 2019.)

In vitro culture offers many advantages for yam germplasm conservation, propagation and international distribution. However, low virus titres in the generated tissues pose a challenge for reliable virus detection, which makes it difficult to ensure that planting material is virus-free. In this study, we evaluated next-generation sequencing (NGS) for virus detection following yam propagation using a robust tissue culture methodology. We detected and assembled the genomes of novel isolates of already characterised viral species of the genera Badnavirus and Potyvirus , confirming the utility of NGS in diagnosing yam viruses and contributing towards the safe distribution of germplasm.

A closed-tube reverse transcription loop-mediated isothermal amplification (CT-RT-LAMP) assay was developed for the detection of yam mosaic virus (YMV, genus Potyvirus) infecting yam (Dioscorea spp.). The assay uses a set of six oligonucleotide primers targeting the YMV coat protein region, and the amplification products in YMV-positive samples are visualized by chromogenic detection with SYBR Green I dye. The CT-RT-LAMP assay detected YMV in leaf and tuber tissues of infected plants. The assay is 100 times more sensitive in detecting YMV than standard RT-PCR, while maintaining the same specificity.

Potyviruses (genus Potyvirus; family Potyviridae) are widely distributed and represent one of the most economically important genera of plant viruses. Therefore, their accurate detection is a key factor in developing efficient control strategies. However, this can sometimes be problematic particularly in plant species containing high amounts of polysaccharides and polyphenols such as yam (Dioscorea spp.). Here, we report the development of a reliable, rapid and cost-effective detection method for the two most important potyviruses infecting yam based on reverse transcription-recombinase polymerase amplification (RT-RPA). The developed method, named 'Direct RT-RPA', detects each target virus directly from plant leaf extracts prepared with a simple and inexpensive extraction method avoiding laborious extraction of high-quality RNA. Direct RT-RPA enables the detection of virus-positive samples in under 30 min at a single low operation temperature (37 °C) without the need for any expensive instrumentation. The Direct RT-RPA tests constitute robust, accurate, sensitive and quick methods for detection of potyviruses from recalcitrant plant species. The minimal sample preparation requirements and the possibility of storing RPA reagents without cold chain storage, allow Direct RT-RPA to be adopted in minimally equipped laboratories and with potential use in plant clinic laboratories and seed certification facilities worldwide., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Since the first discovery of badnaviruses (family Caulimoviridae , genus Badnavirus ) in yam ( Dioscorea spp.) germplasm in the 1970s (Harrison and Roberts, 1973), several hundred partial badnavirus reverse transcriptase (RT)-ribonuclease H (RNaseH) sequences have been characterised ( Kenyon et al. , 2008 ; Bousalem et al. , 2009 ), but only a few complete Dioscorea bacilliform virus (DBV) genome sequences have been reported ( Phillips et al. , 1999 ; Seal and Muller, 2007; Bömer et al. , 2016 and 2017; Sukal et al. , 2017 ; Umber et al. , 2017 ). We have optimised a workflow involving total nucleic acid extractions and rolling circle amplification (RCA) combined with restriction enzyme analysis for the detection and amplification of DBVs present in yam germplasm. We have employed this approach successfully revealing three novel episomal yam badnaviruses ( Bömer et al. , 2016 ). We proposed this to be a complementary method to denaturing gradient gel electrophoresis, which enables a rapid indication of badnavirus diversity as well as the identification of potentially integrated badnavirus sequences in the host genome ( Turaki et al. , 2017 ). Here, we describe the step-by-step protocol to screen yam germplasm for badnavirus infections using RCA as an efficient research tool in the amplification and characterization of novel badnavirus genomes., (Copyright © 2018 The Authors; exclusive licensee Bio-protocol LLC.)

Sugarcane and maize plants showing symptoms typical of those described for the so-called "African streak viruses" (AfSVs) were encountered during field surveys conducted from February to July 2015 to document viruses infecting both crops across the northern Guinea savannah region of Nigeria. As part of this study, two categories of complete mastrevirus-like genome sequences were obtained from nine samples (maize = 2; sugarcane = 7). In pairwise comparisons, the full-length genomes of the first sequence category (2,687 nt each; maize = 2; sugarcane = 2) shared 96 to 99% identity with global isolates of the A-strain of maize streak virus (MSV-A), indicating that sugarcane may also serve as a reservoir host to MSV-A. Analysis of the complete genomes belonging to the second sequence category (2,757 nt each; sugarcane = 5) showed that they shared 42 to 67% identity with their closest AfSV relatives, thus indicating that they represent sequences of a novel mastrevirus. Both sequence categories shared 61-62% sequence identity with each other. Further analysis revealed that the novel sugarcane-infecting virus, tentatively named as sugarcane chlorotic streak virus (SCSV), arose from a putative interspecific recombination event involving two grass-infecting mastreviruses, eragrostis streak virus and urochloa streak virus, as putative parental sequences. The results of this study add to the repertoire of diverse AfSVs present in cereal and sugarcane mixed cropping landscapes in the northern Guinea savannah region of Nigeria, with implications for disease epidemiology.

The yam nematode, Scutellonema bradys , is a major threat to yam ( Dioscorea spp.) production across yam-growing regions. In West Africa, this species cohabits with many morphologically similar congeners and, consequently, its accurate diagnosis is essential for control and for monitoring its movement. In the present study, 46 Scutellonema populations collected from yam rhizosphere and yam tubers in different agro-ecological zones in Ghana and Nigeria were characterised by their morphological features and by sequencing of the D2-D3 region of the 28S rDNA gene and the mitochondrial COI genes. Molecular phylogeny, molecular species delimitation and morphology revealed S. bradys, S. cavenessi, S. clathricaudatum and three undescribed species from yam rhizosphere. Only S. bradys was identified from yam tuber tissue, however. For barcoding and identifying Scutellonema spp., the most suitable marker used was the COI gene. Additionally, 99 new Scutellonema sequences were generated using populations obtained also from banana, carrot, maize and tomato, including the first for S. paralabiatum and S. clathricaudatum , enabling the development of a dichotomous key for identification of Scutellonema spp. The implications of these results are discussed., (© 2017 Yao Kolombia.)

Yam mosaic virus (YMV; genus Potyvirus) is considered to cause the most economically important viral disease of yams (Dioscorea spp.) in West Africa which is the dominant region for yam production globally. Yams are a vegetatively propagated crop and the use of virus-free planting material forms an essential component of disease control. Current serological and PCR-based diagnostic methods for YMV are time consuming involving a succession of target detection steps. In this study, a novel assay for specific YMV detection is described that is based on isothermal reverse transcription-recombinase polymerase amplification (RT-exoRPA). This test has been shown to be reproducible and able to detect as little as 14 pg/μl of purified RNA obtained from an YMV-infected plant, a sensitivity equivalent to that obtained with the reverse transcription-polymerase chain reaction (RT-PCR) in current general use. The RT-exoRPA assay has, however, several advantages over the RT-PCR; positive samples can be detected in less than 30 min, and amplification only requires a single incubation temperature (optimum 37°C). These features make the RT-exoRPA assay a promising candidate for adapting into a field test format to be used by yam breeding programmes or certification laboratories., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Banana and plantain (Musa spp.), produced in 10.3 million ha in the tropics, are among the world's top 10 food crops. They are vegetatively propagated using suckers or tissue culture plants and grown almost as perennial plantations. These are prone to the accumulation of pests and pathogens, especially viruses which contribute to yield reduction and are also barriers to the international exchange of germplasm. The most economically important viruses of banana and plantain are Banana bunchy top virus (BBTV), a complex of banana streak viruses (BSVs) and Banana bract mosaic virus (BBrMV). BBTV is known to cause the most serious economic losses in the "Old World," contributing to a yield reduction of up to 100% and responsible for a dramatic reduction in cropping area. The BSVs exist as episomal and endogenous forms are known to be worldwide in distribution. In India and the Philippines, BBrMV is known to be economically important but recently the virus was discovered in Colombia and Costa Rica, thus signaling its spread into the "New World." Banana and plantain are also known to be susceptible to five other viruses of minor significance, such as Abaca mosaic virus, Abaca bunchy top virus, Banana mild mosaic virus, Banana virus X, and Cucumber mosaic virus. Studies over the past 100 years have contributed to important knowledge on disease biology, distribution, and spread. Research during the last 25 years have led to a better understanding of the virus-vector-host interactions, virus diversity, disease etiology, and epidemiology. In addition, new diagnostic tools were developed which were used for surveillance and the certification of planting material. Due to a lack of durable host resistance in the Musa spp., phytosanitary measures and the use of virus-free planting material are the major methods of virus control. The state of knowledge on BBTV, BBrMV, and BSVs, and other minor viruses, disease spread, and control are summarized in this review., (© 2015 Elsevier Inc. All rights reserved.)

Tuber rot disease is a major constraint to white yam (Dioscorea rotundata) production, accounting for 50-60% of annual yield losses in Nigeria. The main method of control using synthetic fungicides is being discouraged due to human and environmental health hazards. The potential of Oryza sativa husk (OSH) and Quercus phillyraeoides (QP) extracts for the in vitro and in vivo control of six virulent rot-causing fungal pathogens, Lasiodiplodia theobromae, Aspergillus niger, Rhizoctonia solani, Penicillium oxalicum, Sclerotium rolfsii, and Fusarium oxysporum was evaluated, using five different extract concentrations of 0.5%, 1.0%, 1.5%, 2.5%, and 3.5% w/v. These fungi were isolated from rotted tubers of D. rotundata, across three agroecological zones in Nigeria-the Humid rainforest, Derived savanna, and southern Guinea savanna. All treatments were subjected to three methods of inoculation 48 hours before the application of both extracts and stored at 28 ± 2°C for 6 months. Radial mycelial growth of the test pathogens was effectively inhibited at concentrations ≤ 3.5% w/v in vitro for both OSH and QP extracts. Rotting was significantly reduced (P ≤ 0.05) to between 0 to 18.8% and 0% to 20.9% for OSH and QP extracts respectively. The extracts significantly (P ≤ 0.05) inhibited percent rot of the test pathogens at 3.5% concentration w/v in vivo. Rot incidence was, however, lower in replicate tubers that were inoculated, treated with extracts and exposed than treatments that were covered. Phytochemical analysis of OSH and QP extracts revealed the presence of secondary metabolites such as alkaloids, flavonoids, saponins, tannins, ferulic acid, phlobatanins, Terpenoids, phenols, anthraquinone and pyroligneous acid. The efficacy of both extracts in reducing rot in this study recommends their development as prospective biopesticide formulation and use in the management of post-harvest rot of yam tubers.

Yam (Dioscorea spp.) is an important vegetatively-propagated staple crop in West Africa. Viruses are pervasive in yam worldwide, decreasing growth and yield, as well as hindering the international movement of germplasm. Badnaviruses have been reported to be the most prevalent in yam, and genomes of some other badnaviruses are known to be integrated in their host plant species. However, it was not clear if a similar scenario occurs in Dioscorea yam. This study was conducted to verify the prevalence of badnaviruses, and determine if badnavirus genomes are integrated in the yam genome. Leaf samples (n=58) representing eight species of yam from global yam collections kept at CIRAD, France, and 127 samples of D. rotundata breeding lines (n=112) and landraces (n=15) at IITA, Nigeria, were screened using generic badnavirus PCR primers. Positive amplification of an expected ca. 579bp fragment, corresponding to a partial RT-RNaseH region, was detected in 47 (81%) of 58 samples analysed from CIRAD collections, and 100% of the 127 IITA D. rotundata samples. All the D. cayenensis and D. rotundata samples from the CIRAD and IITA collections tested PCR-positive, and sequencing of a selection of the PCR products confirmed they were typical of the genus Badnavirus. A comparison of serological and nucleic acid techniques was used to investigate whether the PCR-positives were sequences amplified from badnavirus particles or putative endogenous badnavirus sequences in the yam genome. Protein A sandwich-enzyme-linked immunosorbent assay (PAS-ELISA) with badnavirus polyclonal antisera detected cross-reacting viral particles in only 60% (92 of 153) of the CIRAD collection samples analysed, in contrast to the aforementioned 81% by PCR. Immunosorbent electron microscopy (ISEM) of virus preparations of a select set of 16 samples, representing different combinations of positive and negative PCR and PAS-ELISA results, identified bacilliform particles in 11 of these samples. Three PCR-positive yam samples from Burkina Faso (cv. Pilimpikou) were identified in which no viral particles were detected by either PAS-ELISA or ISEM. Southern hybridisation results using a yam badnavirus RT-RNaseH sequence (Gn155Dr) as probe, supported a lack of badnavirus particles in the cv. Pilimpikou and identified their equivalent sequences to be of plant genome origin. Probe Gn155Dr, however, hybridised to viral particles and plant genomic DNA in three D. rotundata samples from Guinea. These results represent the first data demonstrating the presence of integrated sequences of badnaviruses in yam. The implications of this for virus-indexing, breeding and multiplication of seed yams are discussed., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Cassava mosaic disease (CMD), caused by different species of cassava mosaic geminiviruses (CMGs), is the most important disease of cassava in Africa and the Indian sub-continent. The cultivated cassava species is protected from CMD by polygenic resistance introgressed from the wild species Manihot glaziovii and a dominant monogenic type of resistance, named CMD2, discovered in African landraces. The ability of the monogenic resistance to confer high levels of resistance in different genetic backgrounds has led recently to its extensive usage in breeding across Africa as well as pre-emptive breeding in Latin America. However, most of the landraces carrying the monogenic resistance are morphologically very similar and come from a geographically restricted area of West Africa, raising the possibility that the diversity of the single-gene resistance could be very limited, or even located at a single locus. Several mapping studies, employing bulk segregant analysis, in different genetic backgrounds have reported additional molecular markers linked to supposedly new resistance genes. However, it is not possible to tell if these are indeed new genes in the absence adequate genetic map framework or allelism tests. To address this important question, a high-density single nucleotide polymorphism (SNP) map of cassava was developed through genotyping-by-sequencing a bi-parental mapping population (N=180) that segregates for the dominant monogenic resistance to CMD. Virus screening using PCR showed that CMD symptoms and presence of virus were strongly correlated (r=0.98). Genome-wide scan and high-resolution composite interval mapping using 6756 SNPs uncovered a single locus with large effect (R(2)=0.74). Projection of the previously published resistance-linked microsatellite markers showed that they co-occurred in the same chromosomal location surrounding the presently mapped resistance locus. Moreover, their relative distance to the mapped resistance locus correlated with the reported degree of linkage with the resistance phenotype. Cluster analysis of the landraces first shown to have this type of resistance revealed that they are very closely related, if not identical. These findings suggest that there is a single source of monogenic resistance in the crop's genepool tracing back to a common ancestral clone. In the absence of further resistance diversification, the long-term effectiveness of the single gene resistance is known to be precarious, given the potential to be overcome by CMGs due to their fast-paced evolutionary rate. However, combining the quantitative with the qualitative type of resistance may ensure that this resistance gene continues to offer protection to cassava, a crop that is depended upon by millions of people in Africa against the devastating onslaught of CMGs., (Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Hypertension is a public health challenge due to its high prevalence, and is a major risk factor for cardiovascular diseases. This study was designed to determine the frequency of the I/D polymorphism of the angiotensin-converting enzyme gene and its association with hypertension in a sample population of Calabar and Uyo, South-South Nigeria., Materials and Methods: A population-based case control design consisting of total of 1224 participants, 612 each of patients and controls, were randomly recruited from hypertension clinics and the general population. The I/D polymorphism was investigated using polymerase chain reaction. Multiple regression and odds ratio (OR) was applied to test whether the ID genotypes were predictors of hypertension., Results: The I/D genotype frequencies were 73(12%), 262(43%) and 277(45%); 74(12%), 303(50%) and 235(38%) for the II, ID, DD genotype in patient and control groups, respectively. A higher frequency of the ID genotype was observed in controls of which 208(61%) were females. By multiple regression analysis, age was a predictor for SBP in patients, r = 0.596, and DBP in controls, r = 0.555. Gender, Body mass index, I/D genotypes were not significant predictors for hypertension but the I/D polymorpism was associated with an increased risk for hypertension with an OR of 1.15 95%CI (0.924-1.456)., Conclusion: The I/D polymorphism of the angiotensin-converting enzyme gene was a risk factor for hypertension in the sample population of Calabar and Uyo. This research will form baseline information for subsequent molecular studies in this population.

Aflatoxin B1 is a carcinogen produced by Aspergillus flavus and a few related fungi that are often present in many food substances. It interacts synergistically with Hepatitis B or C virus (HBV, HBC) infection, thereby increasing the risk of hepatocellular carcinoma (HCC). The G to T transversion at the third position of codon 249 (AGG) of the TP53 gene, substituting arginine to serine, is the most common aflatoxin-induced mutation linked to HCC. This study examined mutations in TP53 by PCR-RFLP analysis and by measurement of an aflatoxin-albumin adduct as a biomarker for human exposure of aflatoxin B1 by indirect-competitive ELISA, in samples collected from healthy controls as well as patients with hepatitis in Hyderabad, Andhra Pradesh, India. A total of 238 blood samples were analyzed the presence of the G to T mutation. Eighteen of these samples were from HBV-positive subjects, 112 of these were from subjects who had HBV-induced liver cirrhosis, and 108 samples were taken from subjects without HBV infection or liver cirrhosis (control group). The G to T mutation was detected in 10 samples, 8 of which were from subjects positive to both HBV and aflatoxin-albumin adduct in blood (p=0.07); whilst two were from individuals who were HBV-negative, but positive for the aflatoxin-albumin adduct (p=0.14). The aflatoxin-albumin adduct was detected in 37 of 238 samples, 29 samples were from HBV-positive subjects and eight were from individuals who were positive for both HBV and the TP53 mutation (p=0.07). The concentration of aflatoxin-albumin adduct ranged from 2.5 to 667pg/mg albumin. Despite low incidence of the G to T mutation, its detection in subjects positive to aflatoxin-adducts is indicative of a strong association between the mutation and aflatoxin exposure in India., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Diverse array of food legume crops (Fabaceae: Papilionoideae) have been adopted worldwide for their protein-rich seed. Choice of legumes and their importance vary in different parts of the world. The economically important legumes are severely affected by a range of virus diseases causing significant economic losses due to reduction in grain production, poor quality seed, and costs incurred in phytosanitation and disease control. The majority of the viruses infecting legumes are vectored by insects, and several of them are also seed transmitted, thus assuming importance in the quarantine and in the epidemiology. This review is focused on the economically important viruses of soybean, groundnut, common bean, cowpea, pigeonpea, mungbean, urdbean, chickpea, pea, faba bean, and lentil and begomovirus diseases of three minor tropical food legumes (hyacinth bean, horse gram, and lima bean). Aspects included are geographic distribution, impact on crop growth and yields, virus characteristics, diagnosis of causal viruses, disease epidemiology, and options for control. Effectiveness of selection and planting with virus-free seed, phytosanitation, manipulation of crop cultural and agronomic practices, control of virus vectors and host plant resistance, and potential of transgenic resistance for legume virus disease control are discussed.

Objectives: The angiotensin II protein is a vasoconstrictor that exerts most of its influence through the angiotensin II type 1 receptor (AT1R). Inconsistent association between the A1166C polymorphism of the AT1R gene and hypertension has been reported among various populations but not among the peoples of Calabar and Uyo. This study was designed to determine the frequency of the A1166C polymorphism of the AT1R gene and its association with hypertension in a sample population of Calabar and Uyo., Materials and Methods: A population-based case control design consisting of total of 1224 participants, 612 each of patients and controls were randomly recruited from hypertension clinics and the general population. Genotyping of the A1166C allele of the AT1R gene to identify variants was performed using polymerase chain reaction and restriction enzyme digestion. Multiple regressions were applied to test whether the A1166 genotypes were predictors of hypertension., Results: 99% of the study population had the wild type AA genotype, and 1% was AC heterozygous carriers of the A1166C polymorphism., Conclusion: The A1166C polymorphism was not a predictor of hypertension in the sample population of Calabar and Uyo.

Uniplex and multiplex reverse transcription-polymerase chain reaction (RT-PCR) protocols were developed for the detection of cassava brown streak viruses (CBSVs) in single and mixed infections with cassava mosaic begomoviruses (CMBs) in a tropical crop plant, cassava (Manihot esculenta). CMBs contain ssDNA as their genome (genus Begomovirus, family Geminiviridae) while CBSVs are made up of positive sense ssRNA (genus Ipomovirus, family Potyviridae), and they cause the economically important cassava mosaic and cassava brown streak diseases, respectively, in sub-Saharan Africa. Diagnostic methodologies have long been available for CMBs but they are limited for CBSVs especially in mixed infections. In this study, the two CBSVs, Cassava brown streak virus (CBSV) and Cassava brown streak Uganda virus (CBSUV) occurring singly or in mixed infection with CMBs, African cassava mosaic virus and East African cassava mosaic virus were detected in a single RT-PCR using both previously described and newly designed virus-specific primers. These protocols were highly efficient for detecting CBSVs compared to the existing methods and have great potential to minimize sample handling and contamination. As well as improving the diagnosis of cassava viruses, the development of multiplex RT-PCR protocols have revealed the common occurrence of mixed infections by CBSV and CBSUV in cassava fields of Tanzania and Kenya, which was contrary to the common belief until recently that these two viruses have existed separately. These protocols have implications for diagnosis and epidemiological studies on cassava virus diseases in Eastern Africa., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Banana bunchy top virus (BBTV) was first reported from sub-Saharan Africa (SSA) from Democratic Republic of Congo (DRC) in the 1950s, has become invasive and spread into 11 countries in the region. To determine the potential threat of BBTV to the production of bananas and plantains (Musa spp.) in the sub-region, field surveys were conducted for the presence of banana bunchy top disease (BBTD) in the DRC, Angola, Cameroon, Gabon and Malawi. Using the DNA-S and DNA-R segments of the virus genome, the genetic diversity of BBTV isolates was also determined from these countries relative to virus isolates across the banana-growing regions around the world. The results established that BBTD is widely prevalent in all parts of DRC, Malawi, Angola and Gabon, in south and western part of Cameroon. Analysis of the nucleotide sequences of DNA-S and DNA-R indicate that BBTV isolates from these countries are genetically identical forming a unique clade within the 'South Pacific' phylogroup that includes isolates from Australia, Egypt, South Asia and South Pacific. These results imply that farmers' traditional practice of transferring vegetative propagules within and between countries, together with virus spread by the widely prevalent banana aphid vector, Pentalonia nigronervosa, could have contributed to the geographic expansion of BBTV in SSA. The results provided a baseline to explore sanitary measures and other 'clean' plant programs for sustainable management of BBTV and its vector in regions where the disease has already been established and prevent the spread of the virus to as yet unaffected regions in SSA., (Copyright © 2011 Elsevier B.V. All rights reserved.)

It was previously shown that pearl millet genotypes carrying a terminal drought tolerance quantitative trait locus (QTL) had a lower transpiration rate (Tr; g cm(-2) d(-1)) under well-watered conditions than sensitive lines. Here experiments were carried out to test whether this relates to leaf abscisic acid (ABA) and Tr concentration at high vapour pressure deficit (VPD), and whether that leads to transpiration efficiency (TE) differences. These traits were measured in tolerant/sensitive pearl millet genotypes, including near-isogenic lines introgressed with a terminal drought tolerance QTL (NIL-QTLs). Most genotypic differences were found under well-watered conditions. ABA levels under well-watered conditions were higher in tolerant genotypes, including NIL-QTLs, than in sensitive genotypes, and ABA did not increase under water stress. Well-watered Tr was lower in tolerant than in sensitive genotypes at all VPD levels. Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40-1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range. It is concluded that two water-saving (avoidance) mechanisms may operate under well-watered conditions in tolerant pearl millet: (i) a low Tr even at low VPD conditions, which may relate to leaf ABA; and (ii) a sensitivity to higher VPD that further restricts Tr, which suggests the involvement of hydraulic signals. Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences. This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines.