I am a Phytovirologists with interest in the molecular biology of viruses, their transmission and management. I also teach plant virology and biotechnology courses at the graduate and postgraduate levels, an astute administrator of research and developer of farmer-friendly extension packages for the management of major plant virus diseases
FUDMA Journal of Agriculture and Agricultural Technology
Surveys were conducted to assess the occurrence of viruses on pepper in 2020 and 2021 dry and wet... more Surveys were conducted to assess the occurrence of viruses on pepper in 2020 and 2021 dry and wet seasons, respectively. Farms in Kaduna, Kano, Bauchi and Gombe States were visited for sampling and sample collection. Leaf samples from plants showing typical viral symptoms were collected for laboratory analysis. The genomic nucleic acid was isolated from the samples by phenol – chloroform separation and purification. The viral coat protein was amplified in Polymerase chain reaction using specific primers and sequenced. Sequences were aligned and used to search the GenBank database for viruses with high similarity. Sequences with high similarity scores were retrieved and used for phylogenetic analysis. Field occurrence of virus-like symptomatic pepper plants ranged from 10 – 70 %. Sequence analysis and phylogeny revealed that the virus infecting Pepper in locations surveyed was highly homologous (94.52%) to Pepper veinal mottle virus. This represents the first confirmation of Pepper ...
African cassava mosaic virus (ACMV) has been identified as a typical example of a pathogenic micr... more African cassava mosaic virus (ACMV) has been identified as a typical example of a pathogenic microorganism that constitutes a global menace to cassava's profitable production, especially in Africa, where the highest economic yield loss of 34 million tons usually is recorded annually. Functional analysis of virus coat proteins based on evolutionary processes and structure of ACMV isolates from fifteen African countries was conducted with Indian cassava mosaic virus and East African cassava mosaic Malawi virus as checks. The study revealed that ACMV coat proteins (CPs) belong to the nuclear export factor BR1 family in the Gemini-coat protein superfamily. Moreover, the phylogenetic analysis performed shows a very strong affinity amongst the African isolates within their geographical regions without evidence of evolutionary divergence amongst all the isolates. Multiple sequence alignment of the genes revealed a highly conserved domain and three motifs. Thirteen of the isolates from ...
Journal of Agriculture and Rural Development in the Tropics and Subtropics, 2020
A field survey was conducted during the 2018 rainy season (June – October) in three major ginger ... more A field survey was conducted during the 2018 rainy season (June – October) in three major ginger producing Local Government Areas (LGAs) of Kaduna State, Nigeria to determine the occurrence and spread of wheat streak mosaic virus (WSMV) infecting ginger. Symptomatic and asymptomatic ginger leaf samples (n=180) and weed samples (n=45) were collected from the surveyed fields and indexed against WSMV using Double Antibody Sandwich Enzyme-linked Immunosorbent Assay (DAS-ELISA). The results obtained showed that WSMV occurred in all the LGAs surveyed but with significant ( P = 0.05 ) variation in distribution. Jaba had the highest virus incidence (22.67\,\%) followed by Kagarko (17.67\,\%) while Kachia had the lowest virus incidence of 10.00\,\%. To the best of our knowledge, this is the first report of WSMV infecting ginger in Nigeria. Rottboellia cochinchinensis (Lour.) Clayton and Setaria barbata (Lam.) Kunth tested positive against WSMV as alternative weed hosts of the virus. The inci...
The family Geminiviridae primarily constitutes an important family of circular single-stranded DN... more The family Geminiviridae primarily constitutes an important family of circular single-stranded DNA (ssDNA) plant-infecting viruses, which pose severe constraints in agricultural production globally and serious threat to food security in sub-Saharan Africa. There are seven known genera, Mastrevirus, Begomovirus, Curtovirus, Becurtovirus, Eragrovirus, and Turncurtovirus of viruses belonging to the family Geminiviridae. Of these, the best characterized economically important species belong to the genus Begomovirus. Begomovirus species are either monopartite (possessing only DNA-A) or bipartite (having both DNA-A and DNA-B components). Majority of the monopartite begomoviruses also have subviral ssDNA satellite components, called DNA α or DNA β. In some cases, defective interfering DNAs can be found in the helper virus due to deletions of some genomic parts associated with bipartite and monopartite begomoviruses. New begomoviral species and their associated subviral components continue ...
Archives Of Phytopathology And Plant Protection, 2004
ABSTRACT Field experiments were conducted for two seasons (2001 and 2002) to determine the reacti... more ABSTRACT Field experiments were conducted for two seasons (2001 and 2002) to determine the reaction of tomato genotypes to Tomato yellow leaf curl Tanzania virus. Tomato plants at the first leaf stage were inoculated with the virus in insect-proof cages in the screenhouse following 48-h and 72-h acquisition and inoculation feeding times by Bemisia tabaci, respectively. After inoculation, the whiteflies were killed with Karate 5EC (a.i 50 g/l λ-cylohalothrin). Test plants were transplanted to the field 4 weeks after inoculation in paired inoculated and non-inoculated plots replicated three times. The plants were maintained insect-free for the duration of the experiment by spraying weekly with Karate 5EC. Disease severity was scored weekly on a scale of 0 – 4 (0 = no symptoms and 4 = very severe symptoms). Average fresh plant weight after harvest (without roots), fruit number per plant, fruit weight and average total yield were recorded. There were significant differences in the effect of disease on yield components between genotypes compared with uninfected controls, except for genotype TY172, which produced insignificant differences (P = 0.5) in all the parameters assessed between the inoculated and uninoculated control plants. The susceptible cultivar Moneymaker had the most severe symptoms of TYLCTZV of all the cultivars tested, while no symptoms were observed on the resistant tomato line TY172. The line TY172 consistently performed better than the rest of the tomato genotypes, followed by Tengeru 97. Tengeru 97 produced the highest mean plant fresh weight and yielded more than the rest of the tomato genotypes tested. It is therefore, suggested that the resistance found in TY172 should be introgressed into Tengeru 97, Cal-J and Moneymaker, which are local tomato varieties preferred by growers in Tanzania. Such efforts will increase and improve the yield and quality of these varieties.
Tomato farms in Arusha, Morogoro, Dodoma, Iringa, Kilimanjaro and Coast regions of Tan- zania wer... more Tomato farms in Arusha, Morogoro, Dodoma, Iringa, Kilimanjaro and Coast regions of Tan- zania were surveyed to assess the incidence of the yellow leaf curl disease, and to collect infected tomato leaf samples for sero-diagnosis. The triple antibody sandwich enzyme linked immunosorbent assay (TAS-ELISA) format was adopted for the detection of disease using commercial polyclonal an- tiserum and monoclonal antibodies SCRI 17, SCRI 20, SCRI 23 and SCRI 33. ELISA readings were rated on a scale of 0-4. The results of the tests indicated that all the Tomato yellow leaf curl virus (TY- LCV) isolates recorded high reaction values (4) with the polyclonal antibody. However, the Dodoma and Arusha isolates were rated highest in optical density (OD) reading with MAb SCRI 20 and 23. The remaining isolates produced lower OD values. All the isolates rated low (2) when tested with SCRI 33. The differences in reaction to the monoclonal antibodies of TYLCV indicated that variability exists between the ...
The tomato yellow leaf curl virus infecting tomato plants in Tanzania is reported to be differ- e... more The tomato yellow leaf curl virus infecting tomato plants in Tanzania is reported to be differ- ent from the Old World geminiviruses. A study was initiated to investigate the transmission proper- ties of the virus such as, acquisition feeding time, inoculation feeding time, persistence of virus in the vector, mechanical inoculation, seed and graft transmission. Results obtained indicate that the virus is transmitted persistently by Bemisia tabaci Genn., but neither mechanically - nor seed-transmissible. Minimum acquisition and inoculation time was 30 minutes. It is concluded that the properties of the agent causing the yellow leaf curl symptoms in tomato plants from different regions of Tanzania are similar and mimic those of tomato yellow leaf curl Begomovirus species studied elsewhere.
A field survey was conducted during the 2018 rainy season (June-October) in three major ginger pr... more A field survey was conducted during the 2018 rainy season (June-October) in three major ginger producing Local Government Areas (LGAs) of Kaduna State, Nigeria to determine the occurrence and spread of Wheat streak mosaic virus (WSMV) infecting ginger. Symptomatic and asymptomatic ginger leaf samples (n=180) and weed samples (n=45) were collected from the surveyed fields and indexed against WSMV using Double Antibody Sandwich Enzyme-linked Immunosorbent Assay (DAS-ELISA). The results obtained showed that WSMV occurred in all the LGAs surveyed but with significant (P = 0.05) variation in distribution. Jaba had the highest virus incidence (22.67 %) followed by Kagarko (17.67 %) while Kachia had the lowest virus incidence of 10.00 %. To the best of our knowledge, this is the first report of WSMV infecting ginger in Nigeria. Rottboellia cochinchinensis (Lour.) Clayton and Setaria barbata (Lam.) Kunth tested positive against WSMV as alternative weed hosts of the virus. The incidence of W...
We report the complete nucleotide sequence of DNA-A of a begomovirus naturally infecting Jatropha... more We report the complete nucleotide sequence of DNA-A of a begomovirus naturally infecting Jatropha curcas L. in Nigeria. Symptoms observed on infected plants were severe mosaic, mottling and blistering of leaves. The virus, which we provisionally name "jatropha mosaic Nigeria virus" (JMNV), has a monopartite genome of 2,779 to 2,789 nucleotides. Pairwise comparisons of DNA-A sequences showed that JMNV had maximum nucleotide sequence identity (72%) with a strain of tomato yellow leaf curl virus. Since there are widespread infections of jatropha in Nigeria showing similar symptoms as those investigated in the present study, JMNV may represent a significant threat to a promising bioenergy crop.
Tomato farms in the Dodoma region of Tanzania where a high incidence of Tomato yellow leaf curl T... more Tomato farms in the Dodoma region of Tanzania where a high incidence of Tomato yellow leaf curl Tanzania virus has been reported were visited to survey for weed hosts. Weeds exhibiting symptoms of infection by the virus were collected and identified. Lysates of leaf samples of the weed species were prepared and clarified by centrifugation. The clarified sap was dotted on nylon membranes and hybridised with a DIG-labelled probe. The putative viral DNA was extracted from the samples by phenol-chloroform procedures, and amplified by polymerase chain reaction methods using a primer pair designed to amplify a 1.2 kb fragment of the virus. Strong hybridisation signals were observed when sap from Ageratum conyzoides and Sida acuta were hybridised to the labelled probe. Similarly, the expected fragment size was obtained after amplification of DNA from both samples. It is concluded that these weeds are new hosts of Tomato yellow leaf curl Tanzania virus. An extensive search for yet undiscove...
... Of the tomato varieties officially recommended for production in Tanzania, Money-Maker, Roma ... more ... Of the tomato varieties officially recommended for production in Tanzania, Money-Maker, Roma VF, Marglobe, Rossol, Tanya and Tengeru 97 (Ministry of Agriculture (MOA), 1992), only Tengeru 97 is tolerant to the disease in Tanzania. ...
Archives Of Phytopathology And Plant Protection, 2007
ABSTRACT DNA was extracted from tomato plants showing symptoms of tomato yellow leaf curl disease... more ABSTRACT DNA was extracted from tomato plants showing symptoms of tomato yellow leaf curl disease. Using degenerate primers PAC1v1978 and PAV1c715, a putative viral fragment of ∼1.2 kb was amplified from the extracted DNA. The amplified viral DNA was isolated, cloned into PstI-digested pBluescript KS plasmid and sequenced. Sequence comparison indicated that the virus causing tomato yellow leaf curl disease in Tanzania was genetically homologous (97% identity in the coat protein) to Tomato leaf curl Tanzania virus. There were no significant differences in DNA sequences among the field isolates from Tanzania.
FUDMA Journal of Agriculture and Agricultural Technology
Surveys were conducted to assess the occurrence of viruses on pepper in 2020 and 2021 dry and wet... more Surveys were conducted to assess the occurrence of viruses on pepper in 2020 and 2021 dry and wet seasons, respectively. Farms in Kaduna, Kano, Bauchi and Gombe States were visited for sampling and sample collection. Leaf samples from plants showing typical viral symptoms were collected for laboratory analysis. The genomic nucleic acid was isolated from the samples by phenol – chloroform separation and purification. The viral coat protein was amplified in Polymerase chain reaction using specific primers and sequenced. Sequences were aligned and used to search the GenBank database for viruses with high similarity. Sequences with high similarity scores were retrieved and used for phylogenetic analysis. Field occurrence of virus-like symptomatic pepper plants ranged from 10 – 70 %. Sequence analysis and phylogeny revealed that the virus infecting Pepper in locations surveyed was highly homologous (94.52%) to Pepper veinal mottle virus. This represents the first confirmation of Pepper ...
African cassava mosaic virus (ACMV) has been identified as a typical example of a pathogenic micr... more African cassava mosaic virus (ACMV) has been identified as a typical example of a pathogenic microorganism that constitutes a global menace to cassava's profitable production, especially in Africa, where the highest economic yield loss of 34 million tons usually is recorded annually. Functional analysis of virus coat proteins based on evolutionary processes and structure of ACMV isolates from fifteen African countries was conducted with Indian cassava mosaic virus and East African cassava mosaic Malawi virus as checks. The study revealed that ACMV coat proteins (CPs) belong to the nuclear export factor BR1 family in the Gemini-coat protein superfamily. Moreover, the phylogenetic analysis performed shows a very strong affinity amongst the African isolates within their geographical regions without evidence of evolutionary divergence amongst all the isolates. Multiple sequence alignment of the genes revealed a highly conserved domain and three motifs. Thirteen of the isolates from ...
Journal of Agriculture and Rural Development in the Tropics and Subtropics, 2020
A field survey was conducted during the 2018 rainy season (June – October) in three major ginger ... more A field survey was conducted during the 2018 rainy season (June – October) in three major ginger producing Local Government Areas (LGAs) of Kaduna State, Nigeria to determine the occurrence and spread of wheat streak mosaic virus (WSMV) infecting ginger. Symptomatic and asymptomatic ginger leaf samples (n=180) and weed samples (n=45) were collected from the surveyed fields and indexed against WSMV using Double Antibody Sandwich Enzyme-linked Immunosorbent Assay (DAS-ELISA). The results obtained showed that WSMV occurred in all the LGAs surveyed but with significant ( P = 0.05 ) variation in distribution. Jaba had the highest virus incidence (22.67\,\%) followed by Kagarko (17.67\,\%) while Kachia had the lowest virus incidence of 10.00\,\%. To the best of our knowledge, this is the first report of WSMV infecting ginger in Nigeria. Rottboellia cochinchinensis (Lour.) Clayton and Setaria barbata (Lam.) Kunth tested positive against WSMV as alternative weed hosts of the virus. The inci...
The family Geminiviridae primarily constitutes an important family of circular single-stranded DN... more The family Geminiviridae primarily constitutes an important family of circular single-stranded DNA (ssDNA) plant-infecting viruses, which pose severe constraints in agricultural production globally and serious threat to food security in sub-Saharan Africa. There are seven known genera, Mastrevirus, Begomovirus, Curtovirus, Becurtovirus, Eragrovirus, and Turncurtovirus of viruses belonging to the family Geminiviridae. Of these, the best characterized economically important species belong to the genus Begomovirus. Begomovirus species are either monopartite (possessing only DNA-A) or bipartite (having both DNA-A and DNA-B components). Majority of the monopartite begomoviruses also have subviral ssDNA satellite components, called DNA α or DNA β. In some cases, defective interfering DNAs can be found in the helper virus due to deletions of some genomic parts associated with bipartite and monopartite begomoviruses. New begomoviral species and their associated subviral components continue ...
Archives Of Phytopathology And Plant Protection, 2004
ABSTRACT Field experiments were conducted for two seasons (2001 and 2002) to determine the reacti... more ABSTRACT Field experiments were conducted for two seasons (2001 and 2002) to determine the reaction of tomato genotypes to Tomato yellow leaf curl Tanzania virus. Tomato plants at the first leaf stage were inoculated with the virus in insect-proof cages in the screenhouse following 48-h and 72-h acquisition and inoculation feeding times by Bemisia tabaci, respectively. After inoculation, the whiteflies were killed with Karate 5EC (a.i 50 g/l λ-cylohalothrin). Test plants were transplanted to the field 4 weeks after inoculation in paired inoculated and non-inoculated plots replicated three times. The plants were maintained insect-free for the duration of the experiment by spraying weekly with Karate 5EC. Disease severity was scored weekly on a scale of 0 – 4 (0 = no symptoms and 4 = very severe symptoms). Average fresh plant weight after harvest (without roots), fruit number per plant, fruit weight and average total yield were recorded. There were significant differences in the effect of disease on yield components between genotypes compared with uninfected controls, except for genotype TY172, which produced insignificant differences (P = 0.5) in all the parameters assessed between the inoculated and uninoculated control plants. The susceptible cultivar Moneymaker had the most severe symptoms of TYLCTZV of all the cultivars tested, while no symptoms were observed on the resistant tomato line TY172. The line TY172 consistently performed better than the rest of the tomato genotypes, followed by Tengeru 97. Tengeru 97 produced the highest mean plant fresh weight and yielded more than the rest of the tomato genotypes tested. It is therefore, suggested that the resistance found in TY172 should be introgressed into Tengeru 97, Cal-J and Moneymaker, which are local tomato varieties preferred by growers in Tanzania. Such efforts will increase and improve the yield and quality of these varieties.
Tomato farms in Arusha, Morogoro, Dodoma, Iringa, Kilimanjaro and Coast regions of Tan- zania wer... more Tomato farms in Arusha, Morogoro, Dodoma, Iringa, Kilimanjaro and Coast regions of Tan- zania were surveyed to assess the incidence of the yellow leaf curl disease, and to collect infected tomato leaf samples for sero-diagnosis. The triple antibody sandwich enzyme linked immunosorbent assay (TAS-ELISA) format was adopted for the detection of disease using commercial polyclonal an- tiserum and monoclonal antibodies SCRI 17, SCRI 20, SCRI 23 and SCRI 33. ELISA readings were rated on a scale of 0-4. The results of the tests indicated that all the Tomato yellow leaf curl virus (TY- LCV) isolates recorded high reaction values (4) with the polyclonal antibody. However, the Dodoma and Arusha isolates were rated highest in optical density (OD) reading with MAb SCRI 20 and 23. The remaining isolates produced lower OD values. All the isolates rated low (2) when tested with SCRI 33. The differences in reaction to the monoclonal antibodies of TYLCV indicated that variability exists between the ...
The tomato yellow leaf curl virus infecting tomato plants in Tanzania is reported to be differ- e... more The tomato yellow leaf curl virus infecting tomato plants in Tanzania is reported to be differ- ent from the Old World geminiviruses. A study was initiated to investigate the transmission proper- ties of the virus such as, acquisition feeding time, inoculation feeding time, persistence of virus in the vector, mechanical inoculation, seed and graft transmission. Results obtained indicate that the virus is transmitted persistently by Bemisia tabaci Genn., but neither mechanically - nor seed-transmissible. Minimum acquisition and inoculation time was 30 minutes. It is concluded that the properties of the agent causing the yellow leaf curl symptoms in tomato plants from different regions of Tanzania are similar and mimic those of tomato yellow leaf curl Begomovirus species studied elsewhere.
A field survey was conducted during the 2018 rainy season (June-October) in three major ginger pr... more A field survey was conducted during the 2018 rainy season (June-October) in three major ginger producing Local Government Areas (LGAs) of Kaduna State, Nigeria to determine the occurrence and spread of Wheat streak mosaic virus (WSMV) infecting ginger. Symptomatic and asymptomatic ginger leaf samples (n=180) and weed samples (n=45) were collected from the surveyed fields and indexed against WSMV using Double Antibody Sandwich Enzyme-linked Immunosorbent Assay (DAS-ELISA). The results obtained showed that WSMV occurred in all the LGAs surveyed but with significant (P = 0.05) variation in distribution. Jaba had the highest virus incidence (22.67 %) followed by Kagarko (17.67 %) while Kachia had the lowest virus incidence of 10.00 %. To the best of our knowledge, this is the first report of WSMV infecting ginger in Nigeria. Rottboellia cochinchinensis (Lour.) Clayton and Setaria barbata (Lam.) Kunth tested positive against WSMV as alternative weed hosts of the virus. The incidence of W...
We report the complete nucleotide sequence of DNA-A of a begomovirus naturally infecting Jatropha... more We report the complete nucleotide sequence of DNA-A of a begomovirus naturally infecting Jatropha curcas L. in Nigeria. Symptoms observed on infected plants were severe mosaic, mottling and blistering of leaves. The virus, which we provisionally name "jatropha mosaic Nigeria virus" (JMNV), has a monopartite genome of 2,779 to 2,789 nucleotides. Pairwise comparisons of DNA-A sequences showed that JMNV had maximum nucleotide sequence identity (72%) with a strain of tomato yellow leaf curl virus. Since there are widespread infections of jatropha in Nigeria showing similar symptoms as those investigated in the present study, JMNV may represent a significant threat to a promising bioenergy crop.
Tomato farms in the Dodoma region of Tanzania where a high incidence of Tomato yellow leaf curl T... more Tomato farms in the Dodoma region of Tanzania where a high incidence of Tomato yellow leaf curl Tanzania virus has been reported were visited to survey for weed hosts. Weeds exhibiting symptoms of infection by the virus were collected and identified. Lysates of leaf samples of the weed species were prepared and clarified by centrifugation. The clarified sap was dotted on nylon membranes and hybridised with a DIG-labelled probe. The putative viral DNA was extracted from the samples by phenol-chloroform procedures, and amplified by polymerase chain reaction methods using a primer pair designed to amplify a 1.2 kb fragment of the virus. Strong hybridisation signals were observed when sap from Ageratum conyzoides and Sida acuta were hybridised to the labelled probe. Similarly, the expected fragment size was obtained after amplification of DNA from both samples. It is concluded that these weeds are new hosts of Tomato yellow leaf curl Tanzania virus. An extensive search for yet undiscove...
... Of the tomato varieties officially recommended for production in Tanzania, Money-Maker, Roma ... more ... Of the tomato varieties officially recommended for production in Tanzania, Money-Maker, Roma VF, Marglobe, Rossol, Tanya and Tengeru 97 (Ministry of Agriculture (MOA), 1992), only Tengeru 97 is tolerant to the disease in Tanzania. ...
Archives Of Phytopathology And Plant Protection, 2007
ABSTRACT DNA was extracted from tomato plants showing symptoms of tomato yellow leaf curl disease... more ABSTRACT DNA was extracted from tomato plants showing symptoms of tomato yellow leaf curl disease. Using degenerate primers PAC1v1978 and PAV1c715, a putative viral fragment of ∼1.2 kb was amplified from the extracted DNA. The amplified viral DNA was isolated, cloned into PstI-digested pBluescript KS plasmid and sequenced. Sequence comparison indicated that the virus causing tomato yellow leaf curl disease in Tanzania was genetically homologous (97% identity in the coat protein) to Tomato leaf curl Tanzania virus. There were no significant differences in DNA sequences among the field isolates from Tanzania.
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Papers by Boniface Kashina