| genetically distinct strains of cassava brown streak virus in the lake victoria basin and the indian ocean coastal area of east africa. | six isolates of cassava brown streak virus (cbsv, genus ipomovirus; potyviridae) from the lake victoria basin in uganda and tanzania were characterized. virus particles were 650 nm long. the complete coat protein (cp)-encoding sequences (1,101 nucleotides, nt) were 90.7-99.5 and 93.7-99.5% identical at the nt and amino acid (aa) levels, respectively. the 3' untranslated region was 225, 226 or 227 nt long. these eight isolates were only 75.8-77.5% (nt) and 87.0-89.9% (aa) identical when compared ... | 2009 | 19184340 |
| the complete genome sequence of the tanzanian strain of cassava brown streak virus and comparison with the ugandan strain sequence. | the complete genome sequence for an isolate of the ugandan and tanzanian strain types of cassava brown streak virus have been determined using the novel approach of non-directed next generation sequencing. comparison of the genome sequences revealed that cbsv is highly heterogeneous at the isolate level as well as the strain level. the isolate of the ugandan strain was found to have a genome 9,070 nucleotides long coding for a polypeptide with 2,902 amino acid residues. the isolate of the tanzan ... | 2010 | 20094895 |
| biotechnological approaches to determine the impact of viruses in the energy crop plant jatropha curcas. | abstract: background: geminiviruses infect a wide range of plant species including jatropha and cassava both belonging to family euphorbiaceae. cassava is traditionally an important food crop in sub - saharan countries, while jatropha is considered as valuable biofuel plant with great perspectives in the future. results: a total of 127 jatropha samples from ethiopia and kenya and 124 cassava samples from kenya were tested by enzyme-linked immunosorbent assay (elisa) for rna virus and polymerase ... | 2011 | 21812981 |
| Low genetic diversity of Squash vein yellowing virus in wild and cultivated cucurbits in the U.S. suggests a recent introduction. | Squash vein yellowing virus (SqVYV) isolates were collected from cultivated and weedy cucurbits representing major hosts and locations in the U.S. and analyzed to better understand the diversity and population structure. No differences in symptoms were observed in field-collected isolate source plants or subsequently inoculated greenhouse plants, and the complete genome of an SqVYV isolate from a wild cucurbit host (smellmelon, Cucumis melo var. dudaim) was highly similar (99.4% nucleotide ident ... | 2011 | 22142477 |
| multiplex rt-pcr assays for the simultaneous detection of both rna and dna viruses infecting cassava and the common occurrence of mixed infections by two cassava brown streak viruses in east africa. | 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 cass ... | 2012 | 22080852 |
| cassava brown streak virus (potyviridae) encodes a putative maf/ham1 pyrophosphatase implicated in reduction of mutations and a p1 proteinase that suppresses rna silencing but contains no hc-pro. | the complete positive-sense single-stranded rna genome of cassava brown streak virus (cbsv; genus ipomovirus; potyviridae) was found to consist of 9,069 nucleotides and predicted to produce a polyprotein of 2,902 amino acids. it was lacking helper-component proteinase but contained a single p1 serine proteinase that strongly suppressed rna silencing. besides the exceptional structure of the 5'-proximal part of the genome, cbsv also contained a maf/ham1-like sequence (678 nucleotides, 226 amino a ... | 2009 | 19386713 |
| absolute quantification of cassava brown streak virus mrna by real-time qpcr. | cassava brown streak disease (cbsd) is the most important virus disease of cassava and a major food security threat in africa. yearly economic losses of up to $100 million usd have been attributed to cbsd. the lack of information on plant-virus interactions has restricted progress in breeding for cbsd resistance. virus quantification is becoming a major tool for the quick and reliable assessment of plant host resistance. therefore, a protocol for specific absolute quantification of cassava brown ... | 2017 | 28315718 |
| a virus-derived stacked rnai construct confers robust resistance to cassava brown streak disease. | cassava brown streak disease (cbsd) threatens food and economic security for smallholder farmers throughout east and central africa, and poses a threat to cassava production in west africa. cbsd is caused by two whitefly-transmitted virus species: cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv) (genus: ipomovirus, family potyviridae). although varying levels of tolerance have been achieved through conventional breeding, to date, effective resistance to cbsd withi ... | 2016 | 28149300 |
| field level rnai-mediated resistance to cassava brown streak disease across multiple cropping cycles and diverse east african agro-ecological locations. | cassava brown streak disease (cbsd) presents a serious threat to cassava production in east and central africa. currently, no cultivars with high levels of resistance to cbsd are available to farmers. transgenic rnai technology was employed to combat cbsd by fusing coat protein (cp) sequences from ugandan cassava brown streak virus (ucbsv) and cassava brown streak virus (cbsv) to create an inverted repeat construct (p5001) driven by the constitutive cassava vein mosaic virus promoter. twenty-fiv ... | 2016 | 28127301 |
| cassava brown streak virus has a rapidly evolving genome: implications for virus speciation, variability, diagnosis and host resistance. | cassava is a major staple food for about 800 million people in the tropics and sub-tropical regions of the world. production of cassava is significantly hampered by cassava brown streak disease (cbsd), caused by cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv). the disease is suppressing cassava yields in eastern africa at an alarming rate. previous studies have documented that cbsv is more devastating than ucbsv because it more readily infects both susceptible an ... | 2016 | 27808114 |
| analysis of the complete genome sequence of euphorbia ringspot virus, an atypical member of the genus potyvirus. | the complete genome sequence of an isolate of euphorbia ringspot virus (eursv) was determined by deep sequencing and rapid amplification of cdna ends (race) rt-pcr. it has an rna genome of 10,154 nucleotides in size, excluding the poly(a) tail, and encodes a polyprotein of 3265 amino acids. phylogenetic analysis from this study supports the earlier taxonomic assignment to the genus potyvirus; however, a gene encoding the ham1h protein, inserted between nib and cp of the eursv genome, which was p ... | 2017 | 27686070 |
| characterization of a new cucurbit-infecting ipomovirus from sudan. | two members of the genus ipomovirus (family potyviridae) are known to infect cucurbits: cucumber vein yellowing virus (cvyv), which is emerging throughout the mediterranean basin, and squash vein yellowing virus (sqvyv), which has been described in america and the caribbean basin, and more recently in israel. in this work, an ipomovirus different from cvyv and sqvyv, tentatively named coccinia mottle virus (cocmov), was detected in a sample of the cucurbit coccinia grandis collected in central s ... | 2016 | 27430562 |
| characterization of brown streak virus-resistant cassava. | cassava brown streak disease (cbsd) has become a major constraint to cassava production in east and central africa. the identification of new sources of cbsd resistance is essential to deploy cbsd mitigation strategies, as the disease is progressing westwards to new geographical areas. a stringent infection method based on top cleft-grafting combined with precise virus titer quantitation was utilized to screen 14 cassava cultivars and elite breeding lines. when inoculated with mixed infections o ... | 2016 | 27070326 |
| artificial microrna-derived resistance to cassava brown streak disease. | artificial mirnas (amirna) were generated targeting conserved sequences within the genomes of the two causal agents of cassava brown streak disease (cbsd): cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv). transient expression studies on ten amirnas targeting 21nt conserved sequences of p1(cbsv and ucbsv), p3(cbsv and ucbsv), ci(ucbsv), nib(cbsv and ucbsv), cp(ucbsv) and the un-translated region (3'-utr) were tested in nicotiana benthamiana. four out of the ten am ... | 2016 | 26912232 |
| comparative analysis of virus-derived small rnas within cassava (manihot esculenta crantz) infected with cassava brown streak viruses. | infection of plant cells by viral pathogens triggers rna silencing, an innate antiviral defense mechanism. in response to infection, small rnas (srnas) are produced that associate with argonaute (ago)-containing silencing complexes which act to inactivate viral genomes by posttranscriptional gene silencing (ptgs). deep sequencing was used to compare virus-derived small rnas (vsrnas) in cassava genotypes nase 3, tme 204 and 60444 infected with the positive sense single-stranded rna (+ssrna) virus ... | 2016 | 26811902 |
| high-throughput multiplex real-time pcr assay for the simultaneous quantification of dna and rna viruses infecting cassava plants. | to develop a multiplex taqman-based real-time pcr assay (qpcr) for the simultaneous detection and quantification of both rna and dna viruses affecting cassava (manihot esculenta) in eastern africa. | 2016 | 26743662 |
| analyses of twelve new whole genome sequences of cassava brown streak viruses and ugandan cassava brown streak viruses from east africa: diversity, supercomputing and evidence for further speciation. | cassava brown streak disease is caused by two devastating viruses, cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv) which are frequently found infecting cassava, one of sub-saharan africa's most important staple food crops. each year these viruses cause losses of up to $100 million usd and can leave entire families without their primary food source, for an entire year. twelve new whole genomes, including seven of cbsv and five of ucbsv were uncovered in this resea ... | 2015 | 26439260 |
| cassava brown streak disease: a threat to food security in africa. | cassava brown streak disease (cbsd) has emerged as the most important viral disease of cassava (manihot esculenta) in africa and is a major threat to food security. cbsd is caused by two distinct species of ipomoviruses, cassava brown streak virus and ugandan cassava brown streak virus, belonging to the family potyviridae. previously, cbsd was reported only from the coastal lowlands of east africa, but recently it has begun to spread as an epidemic throughout the great lakes region of east and c ... | 2015 | 26015320 |
| field evaluation of selected cassava genotypes for cassava brown streak disease based on symptom expression and virus load. | production of cassava (manihot esculenta crantz), a food security crop in sub-saharan africa, is threatened by the spread of cassava brown streak disease (cbsd) which manifests in part as a corky necrosis in the storage root. it is caused by either of two virus species, cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv), resulting in up to 100% yield loss in susceptible varieties. | 2014 | 25526680 |
| efficient transmission of cassava brown streak disease viral pathogens by chip bud grafting. | techniques to study plant viral diseases under controlled growth conditions are required to fully understand their biology and investigate host resistance. cassava brown streak disease (cbsd) presents a major threat to cassava production in east africa. no infectious clones of the causal viruses, cassava brown streak virus (cbsv) or ugandan cassava brown streak virus (ucbsv) are available, and mechanical transmission to cassava is not effective. an improved method for transmission of the viruses ... | 2013 | 24314370 |
| rnai-derived field resistance to cassava brown streak disease persists across the vegetative cropping cycle. | a confined field trial was established to determine durability of rnai-mediated resistance to cassava brown streak disease (cbsd). stem cuttings were obtained from field-grown cassava plants of cv 60444 transgenic for construct p718, consisting of an 894 bp inverted repeat sequence from the ugandan cassava brown streak virus (ucbsv) coat protein. plants were established from three transgenic lines previously shown to provide complete resistance to ucbsv and differing levels of protection to the ... | 2017 | 24296511 |
| exploiting the combination of natural and genetically engineered resistance to cassava mosaic and cassava brown streak viruses impacting cassava production in africa. | cassava brown streak disease (cbsd) and cassava mosaic disease (cmd) are currently two major viral diseases that severely reduce cassava production in large areas of sub-saharan africa. natural resistance has so far only been reported for cmd in cassava. cbsd is caused by two virus species, cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv). a sequence of the cbsv coat protein (cp) highly conserved between the two virus species was used to demonstrate that a cbsv-cp ... | 2012 | 23049780 |
| transgenic rna interference (rnai)-derived field resistance to cassava brown streak disease. | cassava brown streak disease (cbsd), caused by the ipomoviruses cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv), is considered to be an imminent threat to food security in tropical africa. cassava plants were transgenically modified to generate small interfering rnas (sirnas) from truncated full-length (894-bp) and n-terminal (402-bp) portions of the ucbsv coat protein (δcp) sequence. seven sirna-producing lines from each gene construct were tested under confined ... | 2012 | 22845735 |
| loop-mediated isothermal amplification for rapid detection of the causal agents of cassava brown streak disease. | the causal agents of cassava brown streak disease have recently been identified as cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv). primers have been developed for rapid detection of these viruses by reverse transcription loop-mediated isothermal amplification (rt-lamp). performance of the rt-lamp assays compared favourably with published rt-pcr and real-time rt-pcr methods. furthermore, amplification by rt-lamp is completed in 40 min and does not require thermal ... | 2013 | 22820076 |
| widespread occurrence and diversity of cassava brown streak virus (potyviridae: ipomovirus) in tanzania. | cassava brown streak disease (cbsd) has been a problem in tanzania since 1936. existing literature indicated limited distribution of the disease to low altitudes, usually <100 m above sea level, but the current geographical distribution of the disease was not known. whether a single or many strains for the virus exist in tanzania had not been reported to date. in this study, cbsd was recorded from sea level to ≈1,800 m above sea level. in total, 2,730 cassava plants were assessed for cbsd leaf s ... | 2011 | 21916624 |
| reference genes for reliable potyvirus quantitation in cassava and analysis of cassava brown streak virus load in host varieties. | a reliable method for detection and quantitation of viruses associated with cassava brown streak disease (cbsd) is essential to determine their presence in material used for field propagation as well as for precise evaluation of cbsd resistance in the cassava germplasm. quantitative rt-pcr (rt-qpcr) is a well-established method for precise quantitation of viral rna amount in infected tissues. the method requires host reference genes with stable expression patterns under experimental conditions a ... | 2011 | 21756941 |
| rnai-mediated resistance to cassava brown streak uganda virus in transgenic cassava. | cassava brown streak disease (cbsd), caused by cassava brown streak uganda virus (cbsuv) and cassava brown streak virus (cbsv), is of new epidemic importance to cassava (manihot esculenta crantz) production in east africa, and an emerging threat to the crop in central and west africa. this study demonstrates that at least one of these two ipomoviruses, cbsuv, can be efficiently controlled using rna interference (rnai) technology in cassava. an rnai construct targeting the near full-length coat p ... | 2011 | 21726367 |
| comparing the regional epidemiology of the cassava mosaic and cassava brown streak virus pandemics in africa. | the rapid geographical expansion of the cassava mosaic disease (cmd) pandemic, caused by cassava mosaic geminiviruses, has devastated cassava crops in 12 countries of east and central africa since the late 1980s. region-level surveys have revealed a continuing pattern of annual spread westward and southward along a contiguous 'front'. more recently, outbreaks of cassava brown streak disease (cbsd) were reported from uganda and other parts of east africa that had been hitherto unaffected by the d ... | 2011 | 21549776 |
| evolution of cassava brown streak disease-associated viruses. | cassava brown streak disease (cbsd) has occurred in the indian ocean coastal lowlands and some areas of malawi in east africa for decades, and makes the storage roots of cassava unsuitable for consumption. cbsd is associated with cassava brown streak virus (cbsv) and the recently described ugandan cassava brown streak virus (ucbsv) [picorna-like (+)ssrna viruses; genus ipomovirus; family potyviridae]. this study reports the first comprehensive analysis on how evolution is shaping the populations ... | 2011 | 21169213 |
| rnai-mediated resistance to diverse isolates belonging to two virus species involved in cassava brown streak disease. | cassava brown streak disease (cbsd) is emerging as one of the most important viral diseases of cassava (manihot esculenta) and is considered today as the biggest threat to cassava cultivation in east africa. the disease is caused by isolates of at least two phylogenetically distinct species of single-stranded rna viruses belonging to the family potyviridae, genus ipomovirus. the two species are present predominantly in the coastal lowland [cassava brown streak virus (cbsv); tanzania and mozambiq ... | 2011 | 21118347 |
| simultaneous virus-specific detection of the two cassava brown streak-associated viruses by rt-pcr reveals wide distribution in east africa, mixed infections, and infections in manihot glaziovii. | the expanding cassava brown streak disease (cbsd) epidemic in east africa is caused by two ipomoviruses (genus ipomovirus; potyviridae), namely, cassava brown streak virus (cbsv), and ugandan cassava brown streak virus (ucbsv) that was described recently. a reverse transcription polymerase chain reaction (rt-pcr) based diagnostic method was developed in this study for simultaneous virus-specific detection of the two viruses. results showed that cbsv and ucbsv are distributed widely in the highla ... | 2011 | 20923689 |
| transmission studies with cassava brown streak uganda virus (potyviridae: ipomovirus) and its interaction with abiotic and biotic factors in nicotiana benthamiana. | cassava brown streak disease (cbsd), caused by two distinct species, cassava brown streak uganda virus (cbsuv) and cassava brown streak virus (cbsv), is a major constraint to cassava (manihot esculenta crantz) production in africa. absence of infectious clones of cbsuv or cbsv and the lack of efficient means of mechanical transmission of cbsd has hampered laboratory studies of this disease. mechanical transmission, achieved mainly by plant sap inoculation, is a widely used technique for characte ... | 2010 | 20691215 |
| analysis of cassava brown streak viruses reveals the presence of distinct virus species causing cassava brown streak disease in east africa. | cassava brown streak virus (cbsv) isolates were analysed from symptomatic cassava collected between 1997 and 2008 in the major cultivation regions of east africa. an analysis of complete rna genomes of seven isolates from kenya, tanzania, mozambique, uganda and malawi revealed a common genome structure, but the isolates clearly clustered in two distinct clades. the first comprised isolates from kenya, uganda, malawi, north-western tanzania and the cbsv described previously, and shared between 87 ... | 2010 | 20071490 |
| optimization of diagnostic rt-pcr protocols and sampling procedures for the reliable and cost-effective detection of cassava brown streak virus. | sampling procedures and diagnostic protocols were optimized for accurate diagnosis of cassava brown streak virus (cbsv) (genus ipomovirus, family potyviridae). a cetyl trimethyl ammonium bromide (ctab) method was optimized for sample preparation from infected cassava plants and compared with the rneasy plant mini kit (qiagen) for sensitivity, reproducibility and costs. cbsv was detectable readily in total rnas extracted using either method. the major difference between the two methods was in the ... | 2010 | 19879299 |
| [mechanical transmission of cassava brown streak virus]. | | 1959 | 13666823 |
| multiple t-dna delivery to plants using novel mini binary vectors with compatible replication origins. | improved plants are necessary to meet human needs. agrobacterium-mediated transformation is the most common method used to rewire plant capabilities. for plant gene delivery, dna constructs are assembled into binary t-dna vectors that rely on broad host range origins for bacterial replication. here we present plx vectors, a set of mini binary t-dna plasmids suitable for type iis restriction endonuclease- and overlap-based assembly methods. plx vectors include replicons from compatible broad host ... | 2017 | 28657330 |
| a time series transcriptome analysis of cassava (manihot esculenta crantz) varieties challenged with ugandan cassava brown streak virus. | a time-course transcriptome analysis of two cassava varieties that are either resistant or susceptible to cassava brown streak disease (cbsd) was conducted using rnaseq, after graft inoculation with ugandan cassava brown streak virus (ucbsv). from approximately 1.92 billion short reads, the largest number of differentially expressed genes (degs) was obtained in the resistant (namikonga) variety at 2 days after grafting (dag) (3887 degs) and 5 dag (4911 degs). at the same time points, several def ... | 2017 | 28852026 |
| deep sequencing reveals a divergent ugandan cassava brown streak virus isolate from malawi. | illumina sequencing of rna from a cassava cutting from northern malawi produced a genome of ugandan cassava brown streak virus (ucbsv-mw-nb7_2013). sequence comparisons revealed stronger similarity to an isolate from nearby tanzania (93.4% pairwise nucleotide identity) than to those previously reported from malawi (86.9 to 87.0%). | 2017 | 28818908 |
| variations of five eif4e genes across cassava accessions exhibiting tolerant and susceptible responses to cassava brown streak disease. | cassava (manihot esculenta) is an important tropical subsistence crop that is severely affected by cassava brown streak disease (cbsd) in east africa. the disease is caused by cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv). both have a (+)-sense single-stranded rna genome with a 5' covalently-linked viral protein, which functionally resembles the cap structure of mrna, binds to eukaryotic translation initiation factor 4e (eif4e) or its analogues, and then enable ... | 2017 | 28771520 |
| variability in p1 gene redefines phylogenetic relationships among cassava brown streak viruses. | cassava brown streak disease is emerging as the most important viral disease of cassava in africa, and is consequently a threat to food security. two distinct species of the genus ipomovirus (family potyviridae) cause the disease: cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv). to understand the evolutionary relationships among the viruses, 64 nucleotide sequences from the variable p1 gene from major cassava producing areas of east and central-southern africa we ... | 2017 | 28637472 |
| molecular insights into cassava brown streak virus susceptibility and resistance by profiling of the early host response. | cassava brown streak virus (cbsv) and ugandan cassava brown streak virus (ucbsv) are responsible for significant cassava yield losses in eastern sub-saharan africa. to study the possible mechanisms of plant resistance to cbsvs, we inoculated cbsv-susceptible and cbsv-resistant cassava varieties with a mixed infection of cbsvs using top-cleft grafting. transcriptome profiling of the two cassava varieties was performed at the earliest time point of full infection (28 days after grafting) in the su ... | 2017 | 28494519 |
| community phytosanitation to manage cassava brown streak disease. | cassava viruses are the major biotic constraint to cassava production in africa. community-wide action to manage them has not been attempted since a successful cassava mosaic disease control programme in the 1930s/40s in uganda. a pilot initiative to investigate the effectiveness of community phytosanitation for managing cassava brown streak disease (cbsd) was implemented from 2013 to 2016 in two communities in coastal (mkuranga) and north-western (chato) tanzania. cbsd incidence in local variet ... | 2017 | 28487059 |