Phone: +2348074289553 Address: Prof. Onasanya Amos Professor & HOD Chemical Sciences Department of Chemical Sciences Afe Babalola University PMB 5454 Ado-Ekiti Nigeria
Rice yellow mottle virus (RYMV) of the genus Sobemovirus is a major biotic constraint to rice (Or... more Rice yellow mottle virus (RYMV) of the genus Sobemovirus is a major biotic constraint to rice (Oryza sativa) production in Africa. First reported in Kenya during 1966, RYMV was later found in most countries in Africa where rice is grown (1). In countries in westernmost Africa (The Gambia, Guinea-Bissau, Mauritania, and Senegal), plants with leaf yellowing and mottling symptoms were observed, but RYMV was never isolated. Rice is the staple food in The Gambia. In 2006, four samples were collected from local rice varieties in the Kuntaur Region in the center of The Gambia. Mechanical inoculation with leaf extracts from all samples caused typical yellow mottle symptoms on the susceptible rice varieties BG90-2, Bouaké 189, and IR64. RYMV was detected in the four samples collected by ELISA with polyclonal antisera (2). The 720-nt coat protein gene was amplified for each isolate by reverse-transcriptase-PCR with primers 5′-CAAAGATGGCCAGGAA-3′ (sense) and 5′-CTCCCCCACCCATCCCGAGAATT-3′ (anti...
High titer polyclonal antibodies for serological diagnostic purposes were locally produced to for... more High titer polyclonal antibodies for serological diagnostic purposes were locally produced to for- ty isolates of rice yellow mottle virus (RYMV) collected from different sites across four West African countries (18- from Cote d'Ivoire, 2- from Burkina Faso, 5- from Mali and 15- from Niger Repu- blic). This was achieved by immunizing rabbits with purified viral preparations. The primary goal
ABSTRACT An experiment was conducted at Malakabad (Gadera) Dargai Malak and KPK to study the effe... more ABSTRACT An experiment was conducted at Malakabad (Gadera) Dargai Malak and KPK to study the effect of different levels of nitrogen and phosphorus on the yield of maize varieties in randomize complete block design with split plot arrangement. Different fertilization treatments (0:0, 100:0, 100:50, 100:100, 150:0, 150:50, 150:100, 150:150 N:P kg • ha −1) were assigned to main plot while, maize varieties (Azam, Jalal and local) were kept in sub-plots. Data regarding emergence m −2 , days to emergence, days to tasseling, days to silking, number of cobs plant −1 , plant height, grains cob −1 , 1000-grain weight and grain yield were recorded. Emergence m −2 , days to emergence, days to tasseling, days to silking, plant ha −1 at harvest were not significantly affected by different levels of nitrogen and phosphorus while number of cob plant −1 , thousand grains weight, plant height, grains cob −1 and grain yield were significantly affected. Maximum grain yield (5356 kg • ha −1) was recorded in Jalal variety, when it was fertilized with 150:100 N:P kg • ha −1 . Of the factors included in this study, maize cultivars and NP fertilization treatments were dominant in determining grain yield as well as its related components, suggesting that cultivar selection and optimum fertiliza-tion are effective strategies to improve grain yield. However, multiplication and multi-year studies are required to test these results using different cultivars under varying edaphic and climatic con-ditions.
Resistance of Enterococcus faecalis to a wide variety of antibiotics has been severally reported.... more Resistance of Enterococcus faecalis to a wide variety of antibiotics has been severally reported. Antibiotic resistance only cannot explain the virulence of E. faecalis as an emerging pathogen of public health concern, causing a variety of human infections. In the present study, incidence of putative virulence determinants among E. faecalis strains isolated from different categories of food canteens namely; primary-school, fast-food and commoners' canteens (bukataria) in Osun States, Nigeria was investigated. Six hundred and fifty-eight isolates were examined for the expressions of three putative virulence determinant factors; gelatinase, aggregation substance and cytolysin activator by phenotypic tests. Meanwhile, twenty selected representative strains were examined for virulence determinant genes; gelatinase (gelA), aggregation substance (asa 1), cytolysin activator (cylA), enterococcal surface protein (esp) and collagen-binding protein (ace) as well as confirmation of their i...
ABSTRACT Bacterial leaf blight (BLB) of rice is a very destructive disease worldwide and is cause... more ABSTRACT Bacterial leaf blight (BLB) of rice is a very destructive disease worldwide and is caused by Xanthomonas oryzae pv. oryzae (Xoo).The aim of the present study was to examine if the Xoo virulence pathotypes obtained using phenotypic pathotyping could be confirmed using molecular approach. After screening of 60 Operon primers with genomic DNA of two Xoo isolates (virulent pathotype, Vr, and mildly virulent pathotype, MVr), 12 Operon primers that gave reproducible and useful genetic information were selected and used to analyze 50 Xoo isolates from 7 West African countries. Genetic analysis revealed two major Xoo virulence genotypes (Mta and Mtb) with Mta having two subgroups (Mta1 and Mta2). Mta1 (Vr1) subgroup genotype has occurrence in six countries and Mta2 (Vr2) in three countries while Mtb genotype characterized mildly virulence (MVr) Xoo isolates present in five countries. The study revealed possible linkage and correlation between phenotypic pathotyping and molecular typing of Xoo virulence. Xoo virulence genotypes were known to exist within country and there was evidence of Xoo pathogen migration between countries. Durable resistance rice cultivars would need to overcome both Mta and Mtb Xoo virulence genotypes in order to survive after their deployment into different rice ecologies in West Africa.
Rice yellow mottle virus (RYMV) of the genus Sobemovirus is a major biotic constraint to rice (Or... more Rice yellow mottle virus (RYMV) of the genus Sobemovirus is a major biotic constraint to rice (Oryza sativa) production in Africa. First reported in Kenya during 1966, RYMV was later found in most countries in Africa where rice is grown (1). In countries in westernmost Africa (The Gambia, Guinea-Bissau, Mauritania, and Senegal), plants with leaf yellowing and mottling symptoms were observed, but RYMV was never isolated. Rice is the staple food in The Gambia. In 2006, four samples were collected from local rice varieties in the Kuntaur Region in the center of The Gambia. Mechanical inoculation with leaf extracts from all samples caused typical yellow mottle symptoms on the susceptible rice varieties BG90-2, Bouaké 189, and IR64. RYMV was detected in the four samples collected by ELISA with polyclonal antisera (2). The 720-nt coat protein gene was amplified for each isolate by reverse-transcriptase-PCR with primers 5′-CAAAGATGGCCAGGAA-3′ (sense) and 5′-CTCCCCCACCCATCCCGAGAATT-3′ (anti...
High titer polyclonal antibodies for serological diagnostic purposes were locally produced to for... more High titer polyclonal antibodies for serological diagnostic purposes were locally produced to for- ty isolates of rice yellow mottle virus (RYMV) collected from different sites across four West African countries (18- from Cote d'Ivoire, 2- from Burkina Faso, 5- from Mali and 15- from Niger Repu- blic). This was achieved by immunizing rabbits with purified viral preparations. The primary goal
ABSTRACT An experiment was conducted at Malakabad (Gadera) Dargai Malak and KPK to study the effe... more ABSTRACT An experiment was conducted at Malakabad (Gadera) Dargai Malak and KPK to study the effect of different levels of nitrogen and phosphorus on the yield of maize varieties in randomize complete block design with split plot arrangement. Different fertilization treatments (0:0, 100:0, 100:50, 100:100, 150:0, 150:50, 150:100, 150:150 N:P kg • ha −1) were assigned to main plot while, maize varieties (Azam, Jalal and local) were kept in sub-plots. Data regarding emergence m −2 , days to emergence, days to tasseling, days to silking, number of cobs plant −1 , plant height, grains cob −1 , 1000-grain weight and grain yield were recorded. Emergence m −2 , days to emergence, days to tasseling, days to silking, plant ha −1 at harvest were not significantly affected by different levels of nitrogen and phosphorus while number of cob plant −1 , thousand grains weight, plant height, grains cob −1 and grain yield were significantly affected. Maximum grain yield (5356 kg • ha −1) was recorded in Jalal variety, when it was fertilized with 150:100 N:P kg • ha −1 . Of the factors included in this study, maize cultivars and NP fertilization treatments were dominant in determining grain yield as well as its related components, suggesting that cultivar selection and optimum fertiliza-tion are effective strategies to improve grain yield. However, multiplication and multi-year studies are required to test these results using different cultivars under varying edaphic and climatic con-ditions.
Resistance of Enterococcus faecalis to a wide variety of antibiotics has been severally reported.... more Resistance of Enterococcus faecalis to a wide variety of antibiotics has been severally reported. Antibiotic resistance only cannot explain the virulence of E. faecalis as an emerging pathogen of public health concern, causing a variety of human infections. In the present study, incidence of putative virulence determinants among E. faecalis strains isolated from different categories of food canteens namely; primary-school, fast-food and commoners' canteens (bukataria) in Osun States, Nigeria was investigated. Six hundred and fifty-eight isolates were examined for the expressions of three putative virulence determinant factors; gelatinase, aggregation substance and cytolysin activator by phenotypic tests. Meanwhile, twenty selected representative strains were examined for virulence determinant genes; gelatinase (gelA), aggregation substance (asa 1), cytolysin activator (cylA), enterococcal surface protein (esp) and collagen-binding protein (ace) as well as confirmation of their i...
ABSTRACT Bacterial leaf blight (BLB) of rice is a very destructive disease worldwide and is cause... more ABSTRACT Bacterial leaf blight (BLB) of rice is a very destructive disease worldwide and is caused by Xanthomonas oryzae pv. oryzae (Xoo).The aim of the present study was to examine if the Xoo virulence pathotypes obtained using phenotypic pathotyping could be confirmed using molecular approach. After screening of 60 Operon primers with genomic DNA of two Xoo isolates (virulent pathotype, Vr, and mildly virulent pathotype, MVr), 12 Operon primers that gave reproducible and useful genetic information were selected and used to analyze 50 Xoo isolates from 7 West African countries. Genetic analysis revealed two major Xoo virulence genotypes (Mta and Mtb) with Mta having two subgroups (Mta1 and Mta2). Mta1 (Vr1) subgroup genotype has occurrence in six countries and Mta2 (Vr2) in three countries while Mtb genotype characterized mildly virulence (MVr) Xoo isolates present in five countries. The study revealed possible linkage and correlation between phenotypic pathotyping and molecular typing of Xoo virulence. Xoo virulence genotypes were known to exist within country and there was evidence of Xoo pathogen migration between countries. Durable resistance rice cultivars would need to overcome both Mta and Mtb Xoo virulence genotypes in order to survive after their deployment into different rice ecologies in West Africa.
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Papers by Prof. Onasanya Amos