| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |