Micronutrient deficiencies, particularly of iron (Fe) and zinc (Zn), in the diet contribute to he... more Micronutrient deficiencies, particularly of iron (Fe) and zinc (Zn), in the diet contribute to health issues and hidden hunger. Enhancing the Fe and Zn content in globally staple food crops like rice is necessary to address food malnutrition. A Genome-Wide Association Study (GWAS) was conducted using 85 diverse rice accessions from the Democratic Republic of Congo (DRC) to identify genomic regions associated with grain Fe and Zn content. The Fe content ranged from 0.95 to 8.68 mg/100 g on a dry weight basis (dwb) while Zn content ranged from 0.87 to 3.8 mg/100 g (dwb). Using MLM and FarmCPU models, we found 10 significant SNPs out of which one SNP on chromosome 11 was associated with the variation in Fe content and one SNP on chromosome 4 was associated with the Zn content, and both were commonly detected by the two models. Candidate genes belonging to transcription regulator activities, including the bZIP family genes and MYB family genes, as well as transporter activities involved...
Grafting facilitates the exploitation of attributes of two varieties; the scion being responsible... more Grafting facilitates the exploitation of attributes of two varieties; the scion being responsible for the good quality characteristics of the product and the rootstock providing desirable attributes like tolerance to challenges associated with the medium of anchorage. The aim of this study was to evaluate success of in vitro micrografting method in three selected Kenyan papaya lines. In the study, shoot tips; c. 1.0cm were excised from three month old seedlings, sterilised and cultured on Murashige and Skoog basal media supplemented with 0.1mg/l 6-Benzylaminopurine and 0.05mg/l α Naphthalene Acetic Acid. When the shoots reached a length of c. 2.0 cm, the upper 1.0 cm tips were excised and used as scions, while the remaining portion was used as rootstock. The scions and rootstocks of the same genotype were used as the controls. Twenty eight days after grafting, the proportion of scions that were still alive, number of leaves and scion length of individual combinations were recorded. ...
Yam tuber is used as food where it provides cheap, starch-rich food for the hot humid tropics. In... more Yam tuber is used as food where it provides cheap, starch-rich food for the hot humid tropics. In Kenya yam is mainly boiled, fried or roasted although a minority of consumers also process it into flour for use in some baked products. Yams are propagated vegetatively using corms and tuber-sets. In general vegetative propagation is associated with the rapid spread of diseases and is cumbersome. The main objective of this study was to develop an efficient in vitro mass propagation protocol for this particular species. The work involved establishment of the best sterilization procedure for the explants that were initially grown in pots in a screenhouse and then exposed to different levels of commercial bleach (3.5% chlorine). This was followed by culturing the nodal cuttings from the explants in MS media supplemented with different levels of growth regulators. The two step-wise sterilization procedure using commercial bleach was found to be the best and hence recommended for future work. There were significant differences among the treatments with the combination of BAP and IAA at levels of 0.5mg/l of BAP + 0.02mg/l of IAA giving the best results for plantlet regeneration. In vitro rooting was achieved without the use of hormones and the most vigorously growing plantlets acclimatized in the greenhouse. In conclusion, the study found that it is possible to propagate yams in vitro and with the adoption of this protocol for micro-shoot growth, increased rates of multiplication can be achieved. This technique can then be exploited to generate clean, disease-free material both for mass propagation and experimental work.
Yam (Dioscorea spp.), a traditional crop in Kenya has not undergone improvement and little has be... more Yam (Dioscorea spp.), a traditional crop in Kenya has not undergone improvement and little has been done to understand its genetic background. The taxonomy and phylogeny of the local landraces has not been fully studied. The main cultivated species is Dioscorea minutiflora Engl. Others found with low distribution are Dioscorea alata L., Dioscorea bulbifera L. and Dioscorea odoratissima Pax. Flow cytometry was used to estimate the ploidy level of 155 accessions of Kenyan yam including two checks, TDr.18544 a tetraploid and TDc.98136 an octoploid from International Institute of Tropical Agriculture (IITA), Nigeria. Also included in the study were Dioscorea dumetorum Pax, Dioscorea asteriscus Burkill and Dioscorea schimperiana Kunth which are yam wild relatives. Leaf samples were harvested from the field genebank and nuclei extracted using an extraction buffer (Partec GmbH, Munster Germany). Plant nuclei were isolated and stained with propidium iodide then analyzed in a flow cytometer....
A survey was conducted to determine the diversity and distribution of soil nematodes associated w... more A survey was conducted to determine the diversity and distribution of soil nematodes associated with tea in Ngere tea catchment area in Kenya. Soil samples were collected from six electoral zones of Ngere factory in Gatanga division Thika district, Murang’a County, Kenya. Nematodes were extracted and recovered from soil samples using a modified Baermann funnel method and identified under a light microscope based on their morphological characters. They were also classified according to their feeding habits. Ten genera belonging to, bacteriovores, fungivores, and omnivores were identified. Fungal feeding and parasitic nematodes were the most widely distributed trophic groups across the tea catchment area. Plant-parasitic nematodes recovered included Pratylenchus spp., Helicotylenchus spp., Rotylenchus spp., Aphelenchus spp., Rotylenchulus spp., and Xiphinema spp. Tylenchus spp was the most frequently occurring species in the soil (60.47%) where the population was 429 followed by Praty...
The economic value of Arabica coffee ( Coffea arabica L.) is determined mainly by the yield poten... more The economic value of Arabica coffee ( Coffea arabica L.) is determined mainly by the yield potential, the size and shape of raw beans and beverage quality. Bean quality reportedly differ depending on the variety, environmental conditions and management practices. This study aimed at genetically improving raw bean quality of C. arabica cultivar Ruiru 11 through selection within the cultivar. The study also intended to measure the extent to which raw bean quality of Ruiru 11 is affected by the environment. Thirty four Ruiru 11 full-sibs grown in three locations in Kenya exhibiting strong edaphic and climatic differences were used for the study. The three sites were Mariene in Meru, Kisii and Koru. Rainfall amounts during various phases of berry development were used to explain the differences observed in discriminating abilities of the locations for raw bean quality traits. The results showed that beans of desirable AA and AB grades were obtained from Mariene where moderate moisture supply was received during berry expansion and bean filling stages rather than in high rainfall conditions. The best overall Ruiru 11 sibs were identified as R11-121, R11-93, R11-142, R11-52 and R11-71.
Yam landraces in Kenya have not been fully characterized both at morphological and molecular leve... more Yam landraces in Kenya have not been fully characterized both at morphological and molecular level. Application of molecular markers can overcome this bottleneck. One hundred eighty seven accessions comprising 166 yam landraces and 21 Yam DNA samples from IITA, Nigeria were extracted from leaf samples grown at Muguga and genotyped at BeCA. DNA was extracted using CTAB method. Twelve primer pairs were used for genotyping and PCR products detected on ABI-3730 capillary system. Data was analyzed for genetic diversity, ordination and analysis of molecular variance with GenAIEx software. A total of 131 alleles were amplified with a minimum of two alleles and a maximum of 13 alleles per primer with a minimum allele size of 64 bp and a maximum of 368 bp. Accessions from Eastern province had the highest number of unique alleles. Shannon’s information index (I) was 0.1444 for West African samples and 0.2366 for Central province. Accession dispersion revealed four clusters with no distinct ge...
Water stress is one of the major environmental factors that inhibits metabolic processes and cons... more Water stress is one of the major environmental factors that inhibits metabolic processes and constrains plant growth and productivity in the majority of agricultural fields. Wheat is generally grown on arid-agricultural fields and water stress causes serious challenges in wheat production areas. Complimentary experiment on field and greenhouse were conducted at Mekelle University to evaluate the physiological and agronomic traits as screening techniques for yield and drought tolerance in wheat cultivars. Randomized Complete Block Design (RCBD) in factorial combination of six wheat genotypes and three water regimes in three replications were used. Water stress was maintained by withholding water for 10 days at tillering and at booting stages. ANOVA for physiological, agronomic and drought tolerance as well as, yield components revealed a significant difference among the genotypes. Water stress caused reduction in relative water content, initial water content, rate of water loss, yiel...
The Potyvirus Moroccan watermelon mosaic virus (MWMV) naturally infects and severely threatens pr... more The Potyvirus Moroccan watermelon mosaic virus (MWMV) naturally infects and severely threatens production of cucurbits and papaya. In this study, we identified and characterized MWMV isolated from pumpkin (Cucurbita moschata) intercropped with MWMV-infected papaya plants through next-generation sequencing (NGS) and Sanger sequencing approaches. Complete MWMV genome sequences were obtained from two pumpkin samples through NGS and validated using Sanger sequencing. The isolates shared 83.4 to 83.7% nucleotide (nt) and 92.3 to 95.1% amino acid (aa) sequence identities in the coat protein and 79.5 to 79.9% nt and 89.2 to 89.7% aa identities in the polyprotein with papaya isolates of MWMV. Phylogenetic analysis using complete polyprotein nt sequences revealed the clustering of both pumpkin isolates of MWMV with corresponding sequences of cucurbit isolates of the virus from other parts of Africa and the Mediterranean regions, distinct from a clade formed by papaya isolates. Through sap in...
Micronutrient deficiencies, particularly of iron (Fe) and zinc (Zn), in the diet contribute to he... more Micronutrient deficiencies, particularly of iron (Fe) and zinc (Zn), in the diet contribute to health issues and hidden hunger. Enhancing the Fe and Zn content in globally staple food crops like rice is necessary to address food malnutrition. A Genome-Wide Association Study (GWAS) was conducted using 85 diverse rice accessions from the Democratic Republic of Congo (DRC) to identify genomic regions associated with grain Fe and Zn content. The Fe content ranged from 0.95 to 8.68 mg/100 g on a dry weight basis (dwb) while Zn content ranged from 0.87 to 3.8 mg/100 g (dwb). Using MLM and FarmCPU models, we found 10 significant SNPs out of which one SNP on chromosome 11 was associated with the variation in Fe content and one SNP on chromosome 4 was associated with the Zn content, and both were commonly detected by the two models. Candidate genes belonging to transcription regulator activities, including the bZIP family genes and MYB family genes, as well as transporter activities involved...
Grafting facilitates the exploitation of attributes of two varieties; the scion being responsible... more Grafting facilitates the exploitation of attributes of two varieties; the scion being responsible for the good quality characteristics of the product and the rootstock providing desirable attributes like tolerance to challenges associated with the medium of anchorage. The aim of this study was to evaluate success of in vitro micrografting method in three selected Kenyan papaya lines. In the study, shoot tips; c. 1.0cm were excised from three month old seedlings, sterilised and cultured on Murashige and Skoog basal media supplemented with 0.1mg/l 6-Benzylaminopurine and 0.05mg/l α Naphthalene Acetic Acid. When the shoots reached a length of c. 2.0 cm, the upper 1.0 cm tips were excised and used as scions, while the remaining portion was used as rootstock. The scions and rootstocks of the same genotype were used as the controls. Twenty eight days after grafting, the proportion of scions that were still alive, number of leaves and scion length of individual combinations were recorded. ...
Yam tuber is used as food where it provides cheap, starch-rich food for the hot humid tropics. In... more Yam tuber is used as food where it provides cheap, starch-rich food for the hot humid tropics. In Kenya yam is mainly boiled, fried or roasted although a minority of consumers also process it into flour for use in some baked products. Yams are propagated vegetatively using corms and tuber-sets. In general vegetative propagation is associated with the rapid spread of diseases and is cumbersome. The main objective of this study was to develop an efficient in vitro mass propagation protocol for this particular species. The work involved establishment of the best sterilization procedure for the explants that were initially grown in pots in a screenhouse and then exposed to different levels of commercial bleach (3.5% chlorine). This was followed by culturing the nodal cuttings from the explants in MS media supplemented with different levels of growth regulators. The two step-wise sterilization procedure using commercial bleach was found to be the best and hence recommended for future work. There were significant differences among the treatments with the combination of BAP and IAA at levels of 0.5mg/l of BAP + 0.02mg/l of IAA giving the best results for plantlet regeneration. In vitro rooting was achieved without the use of hormones and the most vigorously growing plantlets acclimatized in the greenhouse. In conclusion, the study found that it is possible to propagate yams in vitro and with the adoption of this protocol for micro-shoot growth, increased rates of multiplication can be achieved. This technique can then be exploited to generate clean, disease-free material both for mass propagation and experimental work.
Yam (Dioscorea spp.), a traditional crop in Kenya has not undergone improvement and little has be... more Yam (Dioscorea spp.), a traditional crop in Kenya has not undergone improvement and little has been done to understand its genetic background. The taxonomy and phylogeny of the local landraces has not been fully studied. The main cultivated species is Dioscorea minutiflora Engl. Others found with low distribution are Dioscorea alata L., Dioscorea bulbifera L. and Dioscorea odoratissima Pax. Flow cytometry was used to estimate the ploidy level of 155 accessions of Kenyan yam including two checks, TDr.18544 a tetraploid and TDc.98136 an octoploid from International Institute of Tropical Agriculture (IITA), Nigeria. Also included in the study were Dioscorea dumetorum Pax, Dioscorea asteriscus Burkill and Dioscorea schimperiana Kunth which are yam wild relatives. Leaf samples were harvested from the field genebank and nuclei extracted using an extraction buffer (Partec GmbH, Munster Germany). Plant nuclei were isolated and stained with propidium iodide then analyzed in a flow cytometer....
A survey was conducted to determine the diversity and distribution of soil nematodes associated w... more A survey was conducted to determine the diversity and distribution of soil nematodes associated with tea in Ngere tea catchment area in Kenya. Soil samples were collected from six electoral zones of Ngere factory in Gatanga division Thika district, Murang’a County, Kenya. Nematodes were extracted and recovered from soil samples using a modified Baermann funnel method and identified under a light microscope based on their morphological characters. They were also classified according to their feeding habits. Ten genera belonging to, bacteriovores, fungivores, and omnivores were identified. Fungal feeding and parasitic nematodes were the most widely distributed trophic groups across the tea catchment area. Plant-parasitic nematodes recovered included Pratylenchus spp., Helicotylenchus spp., Rotylenchus spp., Aphelenchus spp., Rotylenchulus spp., and Xiphinema spp. Tylenchus spp was the most frequently occurring species in the soil (60.47%) where the population was 429 followed by Praty...
The economic value of Arabica coffee ( Coffea arabica L.) is determined mainly by the yield poten... more The economic value of Arabica coffee ( Coffea arabica L.) is determined mainly by the yield potential, the size and shape of raw beans and beverage quality. Bean quality reportedly differ depending on the variety, environmental conditions and management practices. This study aimed at genetically improving raw bean quality of C. arabica cultivar Ruiru 11 through selection within the cultivar. The study also intended to measure the extent to which raw bean quality of Ruiru 11 is affected by the environment. Thirty four Ruiru 11 full-sibs grown in three locations in Kenya exhibiting strong edaphic and climatic differences were used for the study. The three sites were Mariene in Meru, Kisii and Koru. Rainfall amounts during various phases of berry development were used to explain the differences observed in discriminating abilities of the locations for raw bean quality traits. The results showed that beans of desirable AA and AB grades were obtained from Mariene where moderate moisture supply was received during berry expansion and bean filling stages rather than in high rainfall conditions. The best overall Ruiru 11 sibs were identified as R11-121, R11-93, R11-142, R11-52 and R11-71.
Yam landraces in Kenya have not been fully characterized both at morphological and molecular leve... more Yam landraces in Kenya have not been fully characterized both at morphological and molecular level. Application of molecular markers can overcome this bottleneck. One hundred eighty seven accessions comprising 166 yam landraces and 21 Yam DNA samples from IITA, Nigeria were extracted from leaf samples grown at Muguga and genotyped at BeCA. DNA was extracted using CTAB method. Twelve primer pairs were used for genotyping and PCR products detected on ABI-3730 capillary system. Data was analyzed for genetic diversity, ordination and analysis of molecular variance with GenAIEx software. A total of 131 alleles were amplified with a minimum of two alleles and a maximum of 13 alleles per primer with a minimum allele size of 64 bp and a maximum of 368 bp. Accessions from Eastern province had the highest number of unique alleles. Shannon’s information index (I) was 0.1444 for West African samples and 0.2366 for Central province. Accession dispersion revealed four clusters with no distinct ge...
Water stress is one of the major environmental factors that inhibits metabolic processes and cons... more Water stress is one of the major environmental factors that inhibits metabolic processes and constrains plant growth and productivity in the majority of agricultural fields. Wheat is generally grown on arid-agricultural fields and water stress causes serious challenges in wheat production areas. Complimentary experiment on field and greenhouse were conducted at Mekelle University to evaluate the physiological and agronomic traits as screening techniques for yield and drought tolerance in wheat cultivars. Randomized Complete Block Design (RCBD) in factorial combination of six wheat genotypes and three water regimes in three replications were used. Water stress was maintained by withholding water for 10 days at tillering and at booting stages. ANOVA for physiological, agronomic and drought tolerance as well as, yield components revealed a significant difference among the genotypes. Water stress caused reduction in relative water content, initial water content, rate of water loss, yiel...
The Potyvirus Moroccan watermelon mosaic virus (MWMV) naturally infects and severely threatens pr... more The Potyvirus Moroccan watermelon mosaic virus (MWMV) naturally infects and severely threatens production of cucurbits and papaya. In this study, we identified and characterized MWMV isolated from pumpkin (Cucurbita moschata) intercropped with MWMV-infected papaya plants through next-generation sequencing (NGS) and Sanger sequencing approaches. Complete MWMV genome sequences were obtained from two pumpkin samples through NGS and validated using Sanger sequencing. The isolates shared 83.4 to 83.7% nucleotide (nt) and 92.3 to 95.1% amino acid (aa) sequence identities in the coat protein and 79.5 to 79.9% nt and 89.2 to 89.7% aa identities in the polyprotein with papaya isolates of MWMV. Phylogenetic analysis using complete polyprotein nt sequences revealed the clustering of both pumpkin isolates of MWMV with corresponding sequences of cucurbit isolates of the virus from other parts of Africa and the Mediterranean regions, distinct from a clade formed by papaya isolates. Through sap in...
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Papers by Edward Mamati