Titles (2)Keywords (1)Abstracts (2)
High-throughput multiplex real-time PCR assay for the simultaneous quantification of DNA and RNA viruses infecting cassava plants, Otti, G., Bouvaine, S., Kimata, B.*, Mkamilo, G.*, Kumar, P. L., Tomlins, K. and Maruthi, M. N., in: Journal of Applied Microbiology, volume 120, number 5, pages 1346-1356, ISSN 1364-5072, 2016. [DOI]
 
Plants infected with mild strains of cassava mosaic geminiviruses (CMGs) outperform initially healthy plants under high CMG inoculum pressure conditions in Uganda, Owor, B., Legg, J., Okao-Okuja, G., Obonyo, R. and Ogenga-Latigo, M.*, in: Paper presented, Entebbe, Uganda, 2002.
 
First Report of Maize chlorotic mottle virus Infecting Maize in the Democratic Republic of the Congo, Lukanda, M.*, Owati, A., Ogunsanya, P., Valimunzigha, K.*, Katsongo, K.*, Ndemere, H.* and Kumar, P. L., in: Plant Disease, volume 98, number 10, pages 1448, ISSN 0191-2917, 2014. [DOI]
 
Keywords:Maize chlorotic mottle virus; Zea mays; Maize; DRC; viruses of plants

Characterisation of resistance in cassava against viruses causing cassava mosaic and cassava brown streak disease in Africa, Koerbler, M., Stein, B., Ingelbrecht, I., Dixon, A. and Winter, S., 2008.
 
Abstract:
Cassava mosaic disease caused by diverse geminiviruses (CMG) and Cassava brown streak disease caused by cassava brown streak virus (CBSV), are key constraints to the cultivation of cassava in Sub-Sahara Africa. We have collected and characterised the diversity of the most prominent geminiviruses from all African cassava cultivation areas and Cassava brown streak viruses from East Africa, to use defined viruses for resistance studies in selected IITA cassava breeding lines and African land races. Virus infections were established in cassava by either graft inoculation with scions of virus infected plants or, by particle bombardment of cloned infectious viruses. Resistance against cassava mosaic geminiviruses was identified in several breeding lines e.g. TME 4, TMS 96/0529 and TMS 96/0160 responding with abortion of virus infections after virus introduction. Other genotypes, e.g. TMS 96/0304, became infected but recovered from symptoms but maintaining the infection status. When cassava clones were analysed for CBSV resistance, it became evident that geminivirus resistance was tightly correlated with susceptibility against CBSV. Geminivirus resistant cassava responded with often severe CBSV infections (e.g. TMS 96/0160) upon virus inoculation. Interestingly, cassava genotypes with an intermediate resistance, TMS 96/0304, initially became mixed infected with CBSV/CMG however subsequently aborting CMG, to establish single CBSV infections. Differential responses were also recorded for strains of CBSV. While CMG resistance in cassava was against all CMG, differential responses were observed in cassava inoculated with CBSV isolates obtained from Kenya and Mozambique. While the CMG susceptible cassava landrace TME 117 was resistant against CBSV from Kenya, it became infected with CBSV from Mozambique. Only the cassava genotype TMS/ 1089A revealed immunity against CMG and also did not establish infections with the CBSV isolates from diverse origins.

First report of cucumber mosaic virus in yams (Dioscorea spp.) in Ghana, Togo and Republic of Benin in West Africa, Eni, A., Kumar, P. L., Asiedu, R., Alabi, O., Naidu, R.*, Hughes, J. and Rey, M.*, in: Plant Disease, volume 92, number 5, pages 833, ISSN 0191-2917, 2008. [DOI]
 
Abstract:
Yam (Dioscorea spp., family Dioscoreaceae) is one of the most important food crops cultivated in the West African yam zone comprising the forest and savannah areas of Nigeria, Ghana, Cote d'Ivoire, Republic of Benin, and Togo, which account for more than 90% of the 4.59 million ha of yam cultivation worldwide (1). A survey was conducted in 2005 to document viruses in yams in Ghana, Togo, and the Republic of Benin. Samples (1,405) from five species of yam showing mosaic, chlorosis, and stunting as well as asymptomatic plants were tested for Dioscorea bacilliform virus (DBV, genus Badnavirus), Yam mosaic virus (YMV, genus Potyvirus), and Yam mild mosaic virus (YMMV, genus Potyvirus), the three most common viruses infecting yams. In addition, samples were tested for Cucumber mosaic virus (CMV), since CMV was previously reported to infect yams in Cote d'Ivoire (2) and Nigeria (3). In protein-A sandwich-ELISA with polyclonal antibodies to a cowpea isolate of CMV, 23 of the 1,405 samples (6 of 218 samples from Togo, 13 of 628 samples from Ghana, and 4 of 559 samples from Republic of Benin) tested positive for CMV. The CMV-positive samples were from D. alata (N = 16) and D. rotundata (N = 7), whereas all samples from D. cayenensis, D. dumetorum, and D. bulbifera tested negative. CMV was detected as mixed infections with DBV, YMV, or YMMV in 21 of 23 samples. Some of these samples showed puckering, chlorosis, mottling, and crinkling, whereas some plants infected by two or more viruses were asymptomatic. Only two samples from D. rotundata had a single infection of CMV and they showed mild chlorotic symptoms in young leaves that were inconspicuous in mature leaves. In sap inoculations, the virus induced systemic mosaic in Nicotiana glutinosa. The presence of CMV in ELISA-positive yam samples was further confirmed by immunocapture-reverse transcription (IC-RT)-PCR using CMV antibodies as trapping antibody and oligonucleotide primers specific for a 485 nt corresponding to 3' end of the coat protein gene and C-terminal noncoding region of RNA-3 (4). To confirm the specificity of ICRT-PCR, the 485-bp amplicons from an isolate from the Republic of Benin was cloned into pCR2.1 (Invitrogen, Carlsbad, CA) and three independent clones were sequenced from both orientations. Pairwise comparison of a consensus sequence (Accession No. EU274471) with corresponding sequences of other CMV isolates deposited in GenBank showed 99% identity at the nucleotide sequence level (Accession No. U22821) and revealed that the CMV isolate from yam belongs to sub-Group IA. To our knowledge, this is the first report of CMV infection in yams (D. alata and D. rotundata) in Ghana, Togo, and the Republic of Benin. Together with a previous documentation of CMV in D. alata and D. trifida in Cote d'Ivoire and Nigeria (2,3), this report adds to existing knowledge on distribution of CMV in yams with implications for yam production and germplasm distribution in the West Africa Region.