scholarly journals Occurrence of African cassava mosaic virus (ACMV) and East African cassava mosaic virus – Uganda (EACMV-UG) in Jatropha curcas

2011 ◽  
Vol 5 (Suppl 7) ◽  
pp. P93 ◽  
Author(s):  
Rose Ramkat ◽  
Alberto Calari ◽  
Fatemeh Maghuly ◽  
Margit Laimer
Keyword(s):  
Mosaic Virus ◽  
Jatropha Curcas ◽  
African Cassava Mosaic Virus ◽  
East African ◽  
Cassava Mosaic Virus

scholarly journals Viruses Infecting Cassava in Kenya

Plant Disease ◽  
2004 ◽  
Vol 88 (1) ◽  
pp. 17-22 ◽  
Author(s):  
H. K. Were ◽  
S. Winter ◽  
E. Maiss
Keyword(s):  
Mosaic Virus ◽  
Viral Disease ◽  
African Cassava Mosaic Virus ◽  
Enzyme Linked Immunosorbent Assay ◽  
Stem Cuttings ◽  
East African ◽  
Western Kenya ◽  
Disease Symptoms ◽  
Future Work ◽  
Cassava Mosaic Virus

A survey of cassava viruses was conducted in major cassava-growing regions of Kenya. A total of 185 leaf samples and 62 stem cuttings from plants with viral disease symptoms were collected and analyzed by biological, electron microscopy, enzyme-linked immunosorbent assay, and polymerase chain reaction. All samples from western Kenya had cassava begomoviruses (African cassava mosaic virus [ACMV], East African cassava mosaic virus [EACMV], and Uganda variant [EACMV-UG]) in either single or in mixed infection. However, all samples from the Coast region were infected with only EACMV, a begomovirus. In addition, 15 samples had mixed infections of EACMV and three other hitherto unidentified filamentous viruses. The viruses observed were 200, 500, 650, and 750 nm long, respectively. In addition to rod-shaped and some flexuous viruses, as seen in a crude sap preparation, pinwheels also were observed, indicating a possible association of some of the viruses with the Potyviridae family. The symptoms induced by these viruses in Nicotiana benthamiana were very severe and often caused about 50% death of the test plants. Back inoculation onto cassava resulted in 100% infections. This finding provides evidence that, other than begomoviruses that cause serious diseases of cassava in Africa, filamentous viruses also are present and, despite their limited distribution, they could reach local significance and, most probably, be as serious as begomoviruses. The implications of these findings are discussed and recommendations for future work suggested.

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 First Report of the Presence of East African Cassava Mosaic Virus in Cameroon

Plant Disease ◽  
1998 ◽  
Vol 82 (10) ◽  
pp. 1172-1172 ◽  
Author(s):  
V. N. Fondong ◽  
J. S. Pita ◽  
C. Rey ◽  
R. N. Beachy ◽  
C. M. Fauquet
Keyword(s):  
Mosaic Virus ◽  
East Africa ◽  
African Cassava Mosaic Virus ◽  
Cassava Mosaic Disease ◽  
Symptom Expression ◽  
Virus Species ◽  
East African ◽  
First Report ◽  
Sequence Identity ◽  
Cassava Mosaic Virus

Cassava mosaic disease (CMD) occurs in all cassava-growing regions of Africa, India, and Sri Lanka. Characterized by mosaic and distortion of cassava leaves and reduced plant growth, causing high yield losses, CMD is caused by geminiviruses (genus Begomovirus, family Geminiviridae) transmitted through infected cuttings or by the whitefly, Bemisia tabaci. Three such geminiviruses have been described: African cassava mosaic virus (ACMV) occurs in most of the cassava-producing zones of Africa; East African cassava mosaic virus (EACMV) in East Africa; and Indian cassava mosaic virus (ICMV) in the Indian subcontinent (1). The two components of ACMV and ICMV genomes, DNA-A and DNA-B, have been sequenced; only DNA-A of EACMV has been identified and sequenced. Variations in symptom expression and severity within the same cassava variety have been observed in Cameroon. To determine the nature of the virus species inducing such variations, 50 samples were collected from CMD-infected plants in the savannah and rainforest zones of Cameroon: 2 from the sahel/savannah plain, 13 from the western highland savannah, and 35 from the main cassava-producing belt of the southwestern rainforest. There is a high incidence of CMD in the rainforest region, with some farms completely infected, while in the savannah regions farms generally have less than 25% incidence. Variation in symptom expression was more common in the rainforest region. Samples were collected from plants with distinct symptoms and/or different extents of symptom severity, then analyzed with the polymerase chain reaction (PCR) with specific primers: JSP1, ATG TCG AAG CGA CCA GGA GAT; JSP2, TGT TTA TTA ATT GCC AAT ACT; and JSP3, CCT TTA TTA ATT TGT CAC TGC. Primer JSP1 anneals to the 5′ end of the coat protein (CP) of ACMV and EACMV; primers JSP2 and JSP3 anneal to the 3′ ends of ACMV and EACMV, respectively. Virus identification was based on presence of an amplified fragment of either virus. ACMV was detected in all 50 samples; EACMV was detected in 8. All samples infected with EACMV were from the southwestern rainforest of Cameroon and were more severely affected by the disease than single infected plants. Previous reports have limited occurrence of EACMV to East Africa (1). This is the first report of the occurrence of EACMV in West Africa. The CP gene of three isolates of EACMV from Cameroon (EACMV/CM) was sequenced from cloned PCR products. There was a high CP nucleotide sequence identity (>99%) with only two amino acid differences among all three EACMV isolates. In contrast, there was a rather low sequence identity (94%) with EACMV/TZ from Tanzania (2), suggesting they may belong to a previously undescribed West African strain of EACMV. This indicates the geminiviruses causing CMD in Africa are more widely distributed than previously reported. None of the Cameroon isolates showed the type of recombination of the EACMV isolate from Uganda (EACMV/ UG) (having the CP core segment the identical to the corresponding ACMV CP sequence) (2). This emphasizes the need for characterization of the viruses causing CMD in different cassava-growing regions of Africa since appropriate control strategies depend on adequate knowledge of disease etiology. References: (1) Y. G. Hong et al. J. Gen. Virol. 74:2437, 1993. (2) X. Zhou et al. J. Gen. Virol. 78:2101, 1997.

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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