scholarly journals The Symptom and Genetic Diversity of Cassava Brown Streak Viruses Infecting Cassava in East Africa

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
I. U. Mohammed ◽  
M. M. Abarshi ◽  
B. Muli ◽  
R. J. Hillocks ◽  
M. N. Maruthi
Keyword(s):  
Protein Gene ◽  
Virus Transmission ◽  
Eastern Africa ◽  
Cassava Brown Streak Disease ◽  
Complete Coat Protein ◽  
Reference Sequences ◽  
Virus Isolates ◽  
Cassava Varieties ◽  
Nicotiana Clevelandii ◽  
Brown Streak

The genetic and symptom diversity of six virus isolates causing cassava brown streak disease (CBSD) in the endemic (Kenya, Mozambique, and Tanzania) and the recently affected epidemic areas (Uganda) of eastern Africa was studied. Five cassava varieties; Albert, Colombian, Ebwanateraka, TMS60444 (all susceptible) and Kiroba (tolerant) were graft inoculated with each isolate. Based on a number of parameters including the severity of leaf and root symptoms, and the extent of virus transmission by grafting, the viruses were classified as either severe or relatively mild. These results were further confirmed by the mechanical inoculation of 13 herbaceous hosts in which the virulent isolates caused plant death inNicotiana clevelandiiandN. benthamianawhereas the milder isolates did not. Phylogenetic analysis of complete coat protein gene sequences of these isolates together with sequences obtained from 14 other field-collected samples from Kenya and Zanzibar, and reference sequences grouped them into two distinct clusters, representing the two species of cassava brown streak viruses. Put together, these results did not suggest the association of a hypervirulent form of the virus with the current CBSD epidemic in Uganda. Identification of the severe and milder isolates, however, has further implications for disease management and quarantine requirements.

scholarly journals Disparity between Leaf and Root Symptoms and Crop Losses Associated with Cassava Brown Streak Disease in Four Countries in Eastern Africa

2015 ◽  
Vol 164 (2) ◽  
pp. 86-93 ◽  
Author(s):  
Rory Hillocks ◽  
Midatharahally Maruthi ◽  
Heneriko Kulembeka ◽  
Simon Jeremiah ◽  
Francis Alacho ◽  
...  
Keyword(s):  
Eastern Africa ◽  
Crop Losses ◽  
Cassava Brown Streak Disease ◽  
Brown Streak

scholarly journals Cassava Brown Streak Disease and Ugandan cassava brown streak virus Reported for the First Time in Zambia

Plant Disease ◽  
2018 ◽  
Vol 102 (7) ◽  
pp. 1410-1418 ◽  
Author(s):  
Rabson M. Mulenga ◽  
Laura M. Boykin ◽  
Patrick C. Chikoti ◽  
Suwilanji Sichilima ◽  
Dickson Ng’uni ◽  
...  
Keyword(s):  
Rating Scale ◽  
Streak Virus ◽  
Sequence Variant ◽  
Cassava Brown Streak Virus ◽  
Cassava Brown Streak Disease ◽  
Polymerase Chain ◽  
Species Specific ◽  
First Time ◽  
Virus Isolates ◽  
Brown Streak

A diagnostic survey was conducted in July 2017 in two northern districts of Zambia to investigate presence or absence of cassava brown streak disease (CBSD) and its causal viruses. In total, 29 cassava fields were surveyed and cassava leaf samples were collected from 116 plants (92 symptomatic and 24 nonsymptomatic). CBSD prevalence was approximately 79% (23 of 29) across fields. Mean CBSD incidence varied across fields but averaged 32.3% while mean disease severity was 2.3 on a 1-to-5 rating scale. Reverse-transcription polymerase chain reaction screening of all 116 samples with one generic and two species-specific primer pairs yielded DNA bands of the expected sizes from all symptomatic plants with the generic (785 bp) and Ugandan cassava brown streak virus (UCBSV)-specific (440 bp) primers. All 24 nonsymptomatic samples were negative for UCBSV and all samples tested negative with primers targeting Cassava brown streak virus. The complete genome of a representative isolate of UCBSV (WP282) was determined to be 9,050 nucleotides in length, minus the poly A tail. A comparative analysis of this isolate with global virus isolates revealed its nature as a sequence variant of UCBSV sharing 94 and 96% maximum complete polyprotein nucleotide and amino acid identities, respectively, with isolates from Malawi (MF379362) and Tanzania (FJ039520). This is the first report of CBSD and UCBSV in Zambia, thus expanding the geographical distribution of the disease and its causal virus and further reinforcing the need to strengthen national and regional phytosanitary programs in Africa.

scholarly journals PAL1 gene of the phenylpropanoid pathway increases resistance to the Cassava brown streak virus in cassava

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Siji Kavil ◽  
Gerald Otti ◽  
Sophie Bouvaine ◽  
Andrew Armitage ◽  
Midatharahally N. Maruthi
Keyword(s):  
Phenylpropanoid Pathway ◽  
Streak Virus ◽  
Rna Seq ◽  
Cassava Brown Streak Virus ◽  
Cassava Brown Streak Disease ◽  
Chalcone Synthase Genes ◽  
Increased Susceptibility ◽  
Cassava Varieties ◽  
Brown Streak

Abstract Background The phenylalanine ammonia lyase genes play crucial role in plant response to biotic and abiotic stresses. In this study, we characterized the role of PAL genes in increasing resistance to the Cassava brown streak virus that causes the economically important cassava brown streak disease (CBSD) on cassava in Africa. Methods The whole transcriptomes of eight cassava varieties differing in resistance to CBSD were obtained at 1, 5 and 8 weeks after CBSV infection. Results Analysis of RNA-Seq data identified the overexpression of PAL1, PAL2, cinnamic acid and two chalcone synthase genes in CBSD-resistant cassava varieties, which was subsequently confirmed by RT-qPCR. The exogenous application of Acibenzolar-S-Methyl induced PAL1 gene expression to enhance resistance in the susceptible var. Kalawe. In contrast, the silencing of PAL1 by RNA interference led to increased susceptibility of the resistant var. Kaleso to CBSD. Conclusions PAL1 gene of the phenylpropanoid pathway has a major role in inducing resistance to CBSD in cassava plants and its early induction is key for CBSD resistance.

scholarly journals Post-harvest impact of cassava brown streak disease in four countries in eastern Africa

Food Chain ◽  
2015 ◽  
Vol 5 (1-2) ◽  
pp. 116-122 ◽  
Author(s):  
Roderick J. Hillocks ◽  
Midatharahally N. Maruthi
Keyword(s):  
Eastern Africa ◽  
Post Harvest ◽  
Cassava Brown Streak Disease ◽  
Harvest Impact ◽  
Brown Streak

scholarly journals Cassava brown streak virus has a rapidly evolving genome: implications for virus speciation, variability, diagnosis and host resistance

2016 ◽  
Author(s):  
Titus Alicai ◽  
Joseph Ndunguru ◽  
Peter Sseruwagi ◽  
Fred Tairo ◽  
Geoffrey Okao-Okuja ◽  
...  
Keyword(s):  
Synonymous Substitution ◽  
Eastern Africa ◽  
Streak Virus ◽  
Yield Losses ◽  
Entire Genome ◽  
Cassava Brown Streak Virus ◽  
Cassava Brown Streak Disease ◽  
The Tropics ◽  
Ngs Data ◽  
Brown Streak

AbstractCassava is a major staple food for about 800 million people in the tropics and subGtropical regions of the world. Production of cassava is significantly hampered by cassava brown streak disease (CBSD), which is 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 and tolerant cassava cultivars, resulting in greater yield losses. Using whole genome sequences from NGS data, we produced the first coalescentGbased species tree estimate for CBSV and UCBSV. This species framework led to the finding that CBSV has a faster rate of evolution when compared with UCBSV. Furthermore, we have discovered that in CBSV, nonsynonymous substitutions are more predominant than synonymous substitution and occur across the entire genome. All comparative analyses between CBSV and UCBSV presented here suggest that CBSV may be outsmarting the cassava immune system, thus making it more devastating and harder to control.

scholarly journals Differential Tropism in Roots and Shoots of Resistant and Susceptible Cassava (Manihot esculenta Crantz) Infected by Cassava Brown Streak Viruses

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1221
Author(s):  
Samar Sheat ◽  
Paolo Margaria ◽  
Stephan Winter
Keyword(s):  
Virus Replication ◽  
Central Africa ◽  
Streak Virus ◽  
Virus Infections ◽  
Long Distance ◽  
Manihot Esculenta Crantz ◽  
Cassava Brown Streak Virus ◽  
Cassava Brown Streak Disease ◽  
Long Distance Movement ◽  
Brown Streak

Cassava brown streak disease (CBSD) is a destructive disease of cassava in Eastern and Central Africa. Because there was no source of resistance in African varieties to provide complete protection against the viruses causing the disease, we searched in South American germplasm and identified cassava lines that did not become infected with the cassava brown streak viruses. These findings motivated further investigations into the mechanism of virus resistance. We used RNAscope® in situ hybridization to localize cassava brown streak virus in cassava germplasm lines that were highly resistant (DSC 167, immune) or that restricted virus infections to stems and roots only (DSC 260). We show that the resistance in those lines is not a restriction of long-distance movement but due to preventing virus unloading from the phloem into parenchyma cells for replication, thus restricting the virus to the phloem cells only. When DSC 167 and DSC 260 were compared for virus invasion, only a low CBSV signal was found in phloem tissue of DSC 167, indicating that there is no replication in this host, while the presence of intense hybridization signals in the phloem of DSC 260 provided evidence for virus replication in companion cells. In neither of the two lines studied was there evidence of virus replication outside the phloem tissues. Thus, we conclude that in resistant cassava lines, CBSV is confined to the phloem tissues only, in which virus replication can still take place or is arrested.

scholarly journals Field evaluation of selected cassava genotypes for cassava brown streak disease based on symptom expression and virus load

2014 ◽  
Vol 11 (1) ◽  
Author(s):  
Tadeo Kaweesi ◽  
Robert Kawuki ◽  
Vincent Kyaligonza ◽  
Yona Baguma ◽  
Geoffrey Tusiime ◽  
...  
Keyword(s):  
Field Evaluation ◽  
Symptom Expression ◽  
Virus Load ◽  
Cassava Brown Streak Disease ◽  
Brown Streak

scholarly journals Sequence variability in the coat protein gene of Cowpea severe mosaic virus isolates from northeastern Brazil

2011 ◽  
Vol 36 (2) ◽  
pp. 121-124 ◽  
Author(s):  
José Evando A. Beserra Jr. ◽  
Eduardo C. Andrade ◽  
Rosa F.R. Araújo Camarço ◽  
Aline K.Q. Nascimento ◽  
José Albérsio A. Lima
Keyword(s):  
Coat Protein ◽  
Mosaic Virus ◽  
Coat Protein Gene ◽  
Protein Gene ◽  
Northeastern Brazil ◽  
Sequence Variability ◽  
Virus Isolates
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