scholarly journals Expression of concern: Sequences enhancing cassava mosaic disease symptoms occur in the cassava genome and are associated with South African cassava mosaic virus infection by A. T. Maredza, F. Allie, G. Plata, M. E. C. Rey

2016 ◽  
Vol 291 (3) ◽  
pp. 1489-1489
Author(s):  
Stefan Hohmann
Keyword(s):  
Virus Infection ◽  
Mosaic Virus ◽  
South African ◽  
Mosaic Disease ◽  
African Cassava Mosaic Virus ◽  
Cassava Mosaic Disease ◽  
Disease Symptoms ◽  
Cassava Mosaic Virus ◽  
Mosaic Virus Infection

scholarly journals Proteome Mapping of South African Cassava Mosaic Virus-Infected Susceptible and Tolerant Landraces of Cassava

Proteomes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 41
Author(s):  
Elelwani Ramulifho ◽  
Marie Emma Christine Rey
Keyword(s):  
Mosaic Virus ◽  
South African ◽  
Post Infection ◽  
Systemic Infection ◽  
Mosaic Disease ◽  
Differentially Expressed ◽  
African Cassava Mosaic Virus ◽  
Cassava Mosaic Disease ◽  
Differentially Expressed Proteins ◽  
Cassava Mosaic Virus

The production of cassava is threatened by the geminivirus South African cassava mosaic virus (SACMV), which causes cassava mosaic disease. Cassava landrace TME3 shows tolerance to SACMV, while T200 is highly susceptible. This study aimed to identify the leaf proteome involved in anti-viral defence. Liquid chromatography mass spectrometry (LC-MS) identified 2682 (54 differentially expressed) and 2817 (206 differentially expressed) proteins in both landraces at systemic infection (32 days post infection) and symptom recovery (67 days post infection), respectively. Differences in the number of differentially expressed proteins (DEPs) between the two landraces were observed. Gene ontology analysis showed that defence-associated pathways such as the chloroplast, proteasome, and ribosome were overrepresented at 67 days post infection (dpi) in SACMV-tolerant TME3. At 67 dpi, a high percentage (56%) of over-expressed proteins were localized in the chloroplast in TME3 compared to T200 (31% under-expressed), proposing that chloroplast proteins play a role in tolerance in TME3. Ribosomal_L7Ae domain-containing protein (Manes.12G139100) was over-expressed uniquely in TME3 at 67 dpi and interacts with the ribosomal protein Sac52 (RPL10). RPL10 is a known key player in the NIK1-mediated effector triggered immunity (ETI) response to geminivirus infection, indicating a possible role for Sac52 in SACMV recovery in TME3. In conclusion, differential protein expression responses in TME3 and T200 may be key to unravel tolerance to CMD.

scholarly journals Variants of East African cassava mosaic virus and Its Distribution in Double Infections with African cassava mosaic virus in Nigeria

Plant Disease ◽  
2003 ◽  
Vol 87 (3) ◽  
pp. 229-232 ◽  
Author(s):  
F. O. Ogbe ◽  
G. Thottappilly ◽  
A. G. O. Dixon ◽  
G. I. Atiri ◽  
H. D. Mignouna
Keyword(s):  
Mosaic Virus ◽  
Mosaic Disease ◽  
African Cassava Mosaic Virus ◽  
Cassava Mosaic Disease ◽  
Single Infection ◽  
East African ◽  
Humid Forest ◽  
Forest Region ◽  
Agroecological Zones ◽  
Cassava Mosaic Virus

In a survey for cassava mosaic begomoviruses conducted in 1997 and 1998 in Nigeria, East African cassava mosaic virus (EACMV) was detected by the polymerase chain reaction together with African cassava mosaic virus (ACMV) in 27 out of 290 cassava leaf samples of infected plants from 254 farmers' fields in five agroecological zones. One plant was infected with EACMV only. Five variant isolates of EACMV were observed based on their reactions to primers that could detect Cameroonian and East African strains of EACMV. Isolates of variants 1 and 3 occurred mostly in the derived or coastal and southern Guinea savannahs, while variants 4 and 5 predominated in the humid forest region. Isolates of variant 2 were widely distributed across the three agroecologies. EACMV was not detected in the northern Guinea savannah and arid and semiarid zones. Most doubly infected plants showed more severe symptoms than plants with single infection. Occurrence of EACMV variants together with ACMV detection and information about their distribution in Nigeria could be used for the selection of cassava clones in cassava mosaic disease resistance programs.

scholarly journals Recombination, pseudorecombination and synergism of geminiviruses are determinant keys to the epidemic of severe cassava mosaic disease in Uganda

2001 ◽  
Vol 82 (3) ◽  
pp. 655-665 ◽  
Author(s):  
J. S. Pita ◽  
V. N. Fondong ◽  
A. Sangaré ◽  
G. W. Otim-Nape ◽  
S. Ogwal ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Mosaic Disease ◽  
African Cassava Mosaic Virus ◽  
Cassava Mosaic Disease ◽  
East African ◽  
Recombinant Fragment ◽  
Complete Sequences ◽  
Natural Recombination ◽  
Cassava Mosaic Virus

The molecular variability of cassava geminiviruses occurring in Uganda was investigated in this study. Infected cassava plants and whiteflies were collected from cassava plantings in different geographical areas of the country and PCR was used for molecular characterization of the viruses. Two complete sequences of DNA-A and -B from African cassava mosaic virus (ACMV), two DNA-A sequences from East African cassava mosaic virus (EACMV), two DNA-B sequences of EACMV and the partial DNA-A nucleotide sequence of a new virus strain isolated in Uganda, EACMV-UG3, are reported here. Analysis of naturally infected cassava plants showed various assortments of DNA-A and DNA-B of the Ugandan viruses, suggesting the occurrence of natural inter- and intraspecies pseudorecombinations and a pattern of cassava mosaic disease (CMD) more complex than previously reported. EACMV-UG2 DNA-A, which contains a recombinant fragment between ACMV and EACMV-UG1 in the coat protein gene that resembles virus from Tanzania, was widespread in the country and always associated with EACMV-UG3 DNA-B, which probably resulted from another natural recombination event. Mixed infections of ACMV-UG and EACMV-UG in cassava and whiteflies were detected in most of the regions where both viruses occurred. These mixed-infected samples always showed extremely severe CMD symptoms, suggesting a synergistic interaction between ACMV-UG and EACMV-UG2. The first demonstration is provided of infectivity of EACMV clones to cassava, proving conclusively that the pseudorecombinant EACMV-UG2 DNA-A+EACMV-UG3 DNA-B is a causal agent of CMD in Uganda.

scholarly journals Survey, Molecular Detection, and Characterization of Geminiviruses Associated with Cassava Mosaic Disease in Zambia

Plant Disease ◽  
2016 ◽  
Vol 100 (7) ◽  
pp. 1379-1387 ◽  
Author(s):  
Rabson M. Mulenga ◽  
James P. Legg ◽  
Joseph Ndunguru ◽  
Douglas W. Miano ◽  
Eunice W. Mutitu ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Mosaic Disease ◽  
Disease Spread ◽  
African Cassava Mosaic Virus ◽  
Cassava Mosaic Disease ◽  
Virus Infections ◽  
East African ◽  
A Genome ◽  
The Status ◽  
Cassava Mosaic Virus

A survey was conducted from April to May 2014 in 214 farmers’ fields located across six major cassava-producing provinces (Western, Northwestern, Northern, Luapula, Lusaka, and Eastern) of Zambia to determine the status of cassava mosaic disease (CMD) and the species diversity of associated cassava mosaic geminiviruses (CMG). Mean CMD incidence varied across all six provinces but was greatest in Lusaka Province (81%) and least in Northern Province (44%). Mean CMD severity varied slightly between provinces, ranging from 2.78 in Eastern Province to 3.00 in Northwestern Province. Polymerase chain reaction discrimination of 226 survey samples, coupled with complete DNA-A genome sequence analysis, revealed the presence of African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV), and East African cassava mosaic Malawi virus (EACMMV) as single or mixed infections of different proportions. Single-virus infections were predominant, occurring in 62.8% (ACMV), 5.8% (EACMMV), and 2.2% (EACMV) of samples relative to mixed-virus infections, which occurred in 19.5% (ACMV + EACMMV), 0.4% (ACMV + EACMV), and 0.9% (ACMV + EACMV + EACMMV) of samples. Phylogenetic analysis revealed the segregation of virus isolates from Zambia into clades specific to ACMV, EACMV, and EACMMV, further confirming the presence of all three viruses in Zambia. The results point to a greater diversity of CMG across major cassava-growing provinces of Zambia and implicate contaminated cassava cuttings in disease spread.

scholarly journals Two Novel DNAs That Enhance Symptoms and Overcome CMD2 Resistance to Cassava Mosaic Disease

2016 ◽  
Vol 90 (8) ◽  
pp. 4160-4173 ◽  
Author(s):  
Joseph Ndunguru ◽  
Leandro De León ◽  
Catherine D. Doyle ◽  
Peter Sseruwagi ◽  
German Plata ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Dna Sequences ◽  
Large Scale ◽  
Indian Subcontinent ◽  
Mosaic Disease ◽  
African Cassava Mosaic Virus ◽  
Cassava Mosaic Disease ◽  
Resistance Locus ◽  
East African ◽  
Cassava Mosaic Virus

ABSTRACTCassava mosaic begomoviruses (CMBs) cause cassava mosaic disease (CMD) across Africa and the Indian subcontinent. Like all members of the geminivirus family, CMBs have small, circular single-stranded DNA genomes. We report here the discovery of two novel DNA sequences, designated SEGS-1 and SEGS-2 (forsequencesenhancinggeminivirussymptoms), that enhance symptoms and break resistance to CMD. The SEGS are characterized by GC-rich regions and the absence of long open reading frames. Both SEGS enhanced CMD symptoms in cassava (Manihot esculentaCrantz) when coinoculated withAfrican cassava mosaic virus(ACMV),East African cassava mosaic Cameroon virus(EACMCV), orEast African cassava mosaic virus-Uganda(EACMV-UG). SEGS-1 also overcame resistance of a cassava landrace carrying the CMD2 resistance locus when coinoculated with EACMV-UG. Episomal forms of both SEGS were detected in CMB-infected cassava but not in healthy cassava. SEGS-2 episomes were also found in virions and whiteflies. SEGS-1 has no homology to geminiviruses or their associated satellites, but the cassava genome contains a sequence that is 99% identical to full-length SEGS-1. The cassava genome also includes three sequences with 84 to 89% identity to SEGS-2 that together encompass all of SEGS-2 except for a 52-bp region, which includes the episomal junction and a 26-bp sequence related to alphasatellite replication origins. These results suggest that SEGS-1 is derived from the cassava genome and facilitates CMB infection as an integrated copy and/or an episome, while SEGS-2 was originally from the cassava genome but now is encapsidated into virions and transmitted as an episome by whiteflies.IMPORTANCECassava is a major crop in the developing world, with its production in Africa being second only to maize. CMD is one of the most important diseases of cassava and a serious constraint to production across Africa. CMD2 is a major CMD resistance locus that has been deployed in many cassava cultivars through large-scale breeding programs. In recent years, severe, atypical CMD symptoms have been observed occasionally on resistant cultivars, some of which carry the CMD2 locus, in African fields. In this report, we identified and characterized two DNA sequences, SEGS-1 and SEGS-2, which produce similar symptoms when coinoculated with cassava mosaic begomoviruses onto a susceptible cultivar or a CMD2-resistant landrace. The ability of SEGS-1 to overcome CMD2 resistance and the transmission of SEGS-2 by whiteflies has major implications for the long-term durability of CMD2 resistance and underscore the need for alternative sources of resistance in cassava.

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