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 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 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 Host and virus effects on reversion in cassava affected by cassava brown streak disease

2015 ◽  
Vol 65 (4) ◽  
pp. 593-600 ◽  
Author(s):  
I. U. Mohammed ◽  
S. Ghosh ◽  
M. N. Maruthi
Keyword(s):  
Cassava Brown Streak Disease ◽  
Brown Streak

Expansion of the cassava brown streak disease epidemic in eastern Democratic Republic of Congo

Plant Disease ◽  
2020 ◽  
Author(s):  
Clérisse Mubasi Casinga ◽  
Rudolph R Shirima ◽  
N M Mahungu ◽  
W Tata-Hangy ◽  
Kalinga Benoit Bashizi ◽  
...  
Keyword(s):  
Democratic Republic ◽  
Democratic Republic Of Congo ◽  
Smallholder Farmers ◽  
Central Africa ◽  
Virus Detection ◽  
Streak Virus ◽  
Republic Of Congo ◽  
Cassava Brown Streak Virus ◽  
Cassava Brown Streak Disease ◽  
Brown Streak

Cassava plays a key role in assuring food security and generating income for smallholder farmers throughout central Africa, and particularly in the Democratic Republic of Congo (DRC). This status is threatened, however, by cassava brown streak disease (CBSD) which has recently expanded its incidence and range in eastern DRC. The study described here, comprises the first extensive assessment of temporal change in occurrence of CBSD and its causal viruses in DRC, based on surveys conducted during 2016 and 2018. Cassava fields were inspected in Ituri, Nord-Kivu, Sud-Kivu, Tanganyika and Haut-Katanga provinces within eastern DRC, to record foliar incidence and severity of CBSD. Leaf samples were collected for virus detection and species-level identification. New occurrences of CBSD, confirmed by virus diagnostic tests, were recorded in two provinces (Haut-Katanga and Sud-Kivu) and nine previously unaffected territories, covering an area of > 62,000 km2, and at up to 900 km from locations of previously published reports of CBSD in DRC. Overall, average CBSD incidence within fields was 13.2% in 2016 and 16.1% in 2018. In the new spread zone of Haut-Katanga, incidence increased from 1.7% to 15.9%. CBSD is now present in provinces covering 321,000 km2 which is approximately 14% of the total area of DRC. This represents a major expansion of the CBSD epidemic, which was only recorded from one province (Nord-Kivu) in 2012. Both cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) were detected in Ituri, Nord-Kivu and Sud-Kivu, but only CBSV was detected in Haut-Katanga. Considered overall, these results confirm the increasing threat that CBSD poses to cassava production in DRC and describe an important expansion in the African pandemic of CBSD.

scholarly journals Cassava brown streak disease: a threat to food security in Africa

2015 ◽  
Vol 96 (5) ◽  
pp. 956-968 ◽  
Author(s):  
Basavaprabhu L. Patil ◽  
Edward Kanju ◽  
James P. Legg ◽  
Claude M. Fauquet
Keyword(s):  
Food Security ◽  
Cassava Brown Streak Disease ◽  
Brown Streak
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