Browsing by Author "Anami, Sylvester E."
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Item Drought Response in Selected Tropical Inbred Maize Lines and Relative Expression of PARP2 Gene under Limited Water Conditions(Science Publishing Group, 2018-04) Muli, Joshua K.; Budambula, Nancy; Mweu, Cecilia; Anami, Sylvester E.Drought is the leading single factor that limits maize production thus inhibiting the crops genetic potential. In response to drought, maize and other plants synthesize Poly ADP-Ribose (PAR) protein. This process is controlled by the Poly ADP-Ribose Polymerase (PARP) genes and consumes cellular energy, leading to plant death. This study evaluated four tropical inbred maize (Zea mays L.) lines; CML 216, CML 144, A04 and E04 for their response to growth limiting water stress and their relative expression of PARP2 gene under drought and non-drought conditions. The leaf lengths and growth rates of the fourth leaf were monitored for 21days post emergence while fresh and dry weights of drought stressed and non-stressed seedlings were recorded a month after emergence of the fourth leaf. The relative expression of PARP2 gene was determined using rtPCR after isolating RNA from drought stressed and non-stressed maize seedlings. There was no significant difference in the mature lengths of the fourth leaf in the four genotypes when the maize seedlings were not subjected to drought and when subjected to severe drought stress. However, subjecting maize seedlings to mild drought resulted in a significant difference in the mature leaf lengths based on the different genotypes (P= 0.0066). The growth rate of maize seedlings based on the fourth leaf was observed to be affected by drought, with a higher mean growth rate (1.74 cm day-1) registered in seedlings which were not subjected to drought and those subjected to moderate drought (1.78 cm day-1). A slower growth rate (1.37 cm day-1) was observed in seedlings subjected to severe drought stress. Fresh and dry weights of maize seedlings were also observed to be significantly different based on the level of drought exerted (P = < 0.0001) and the genotype (P = < 0.0001). The expression of PARP2 gene was found to be directly proportiItem Evaluation of prokaryotic diversity of five hot springs in Eritrea(BioMed Central, 2017-09) Ghilamicael, Amanuel M.; Budambula, Nancy; Anami, Sylvester E.; Mehari, Tadesse; Boga, Hamadi I.Background: Total community rDNA was used to determine the diversity of bacteria and archaea from water, wet sediment and microbial mats samples of hot springs in the Eastern lowlands of Eritrea. The temperatures of the springs range from 49.5 °C to 100 °C while pH levels varied from 6.97 to 7.54. Akwar and Maiwooi have high carbonate levels. The springs near the seashore, Garbanabra and Gelti, are more saline with higher levels of sodium and chlorides. Elegedi, situated in the Alid volcanic area, has the highest temperature, iron and sulfate concentrations. Results: The five hot springs shared 901 of 4371 OTUs recovered while the three sample types (water, wet sediment and microbial mats) also shared 1429 OTUs. The Chao1 OTU estimate in water sample was significantly higher than the wet sediment and microbial mat samples. As indicated by NMDS, the community samples at genus level showed location specific clustering. Certain genera correlated with temperature, sodium, carbonate, iron, sulfate and ammonium levels in water. The abundant phyla included Proteobacteria (6.2–82.3%), Firmicutes (1.6–63.5%), Deinococcus-Thermus (0.0–19.2%), Planctomycetes (0.0–11.8%), Aquificae (0.0–9.9%), Chlorobi (0.0–22.3%) and Bacteroidetes (2.7–8.4%). Conclusion: There were significant differences in microbial community structure within the five locations and sample types at OTU level. The occurence of Aquificae, Deinococcus-Thermus, some Cyanobacteria and Crenarchaeota were highly dependent on temperature. The Halobacterium, unclassified Thaumarchaeota, Actinobacteria and Cyanobacteria showed significant correlation with salinity occurring abundantly in Garbanabra and Gelti. Firmicutes and unclassified Rhodocylaceae were higher in the microbial mat samples, while Archaea were prominent in the wet sediment samples.Item Genetic Improvement of African Maize towards Drought Tolerance: A Review(IISTE, 2016) Budambula, Nancy; Muli, Jushua K.; Mweu, Cecilia; Imbo, Mary C.; Anami, Sylvester E.Africa supports a population of over 1 billion people with over half of them depending on maize for food and feed either directly or indirectly. Maize in Africa is affected by many stresses, both biotic and abiotic which significantly reduce yields and eventually lead to poor production. Due to the high demand for maize in the region, different improvement strategies have been employed in an effort to improve production. These include conventional breeding, molecular breeding, high throughput phenotyping techniques and remote sensing-based techniques. Conventional breeding techniques such as open pollination have been used to develop drought avoiding maize varieties like the Kito open pollinated variety (OPV) of Tanzania and Guto OPV of Ethiopia. A combination of conventional breeding and molecular biology techniques has led to improved breeding strategies like the Marker Assisted Back Crossing (MABC) and Marker Assisted Recurrent Selection (MARS). These techniques have been used to improve drought tolerance in existing inbred maize lines like the CML 247 and CML 176. Through genetic engineering, different genes including C4-PEPC, NPK1, betA, ZmNF-YB2, cspB, ZmPLC1 and TsVP have been cloned in maize. Transgenic maize crops expressing these genes have shown increased tolerance to drought stress. Although there is substantial progress towards developing drought tolerant maize, many African farmers are yet to benefit from this technology. This is due to lack of an enabling policy framework as well as a limited financial investment in biotechnology research.Item Genetic Transformation of Sweet Potato for Improved Tolerance to Stress: A Review(2016-10) Imbo, Mary C.; Budambula, Nancy; Mweu, Cecilia M.; Muli, Joshua K.; Anami, Sylvester E.The sweet potato (Ipomoea batatas Lam) is a major staple food in many parts of the world. Sweet potato leaves and tubers are consumed as food and livestock feed. Biotic and abiotic stresses affect yield leading to a reduction in production. This review analyzes factors limiting sweet potato production and the progress made towards stress tolerance using genetic transformation. Genetic transformation could enhance yield, nutritional value and tolerance to stress. Transgenic sweet potatoes tolerant to biotic and abiotic stress, improved nutritional value and higher yields have been developed. Sweet potato expressing the endotoxin cry8Db, cry7A1 and cry3Ca genes showed lower sweet potato weevil infestation than non-transformed lines. Transgenic cultivar ‘Xushu18’ expressing the oryzacystatin-1 (OC1) gene showed enhanced resistance to sweet potato stem nematodes. Sweet potato line ‘Chikei 682-11’ expressing the coat protein (CP) exhibited resistance to the sweet potato feathery mottle virus (SPFMV). Transgenics expressing the rice cysteine inhibitor gene oryzacystatin-1 (OC1) also exhibited resistance to the SPFMV. Transgenic cultivar ‘Kokei’ expressing the spermidine synthetase gene FSPD1 had higher levels of spermine in the leaves and roots, and displayed enhanced tolerance to drought and salt stress. ‘Shangshu’ variety expressing the IbMas has shown enhanced tolerance to salt stress. Transgenic ‘Lixixiang’ expressing IbMIPSI showed an up-regulation of metabolites involved in stress response to drought, salinity and nematode infestation. Transgenic ‘Yulmi’ sweet potato transformed with copper/zinc superoxide dismutase (CuZnSOD) gene showed an enhanced tolerance to methyl viologen induced oxidative and chilling stress. Similarly, transformation of cultivar ‘Sushu-2’ with betaine aldehyde dehydrogenase (BADH) gene resulted in transgenics tolerant to salt, chilling and oxidative stress. Sweet potato varieties ‘Kokei14’ and ‘Yulmi’ transformed with the bar gene were shown to be tolerant to application of the herbicide Basta. The development of stress tolerant varieties will immensely increase the area under sweet potato production and eventually promote the adoption of sweet potato as a commercial crop. Sweet potato research and breeding for stress tolerance still faces technical and socio-political hurdles. Despite these challenges, genetic transformation remains a viable method with immense potential for the improvement of sweet potato.Item Physical and Chemical Characteristics of Five Hot Springs in Eritrea(IISTE, 2017-07) Ghilamicael, Amanuel M.; Boga, Hamadi I.; Anami, Sylvester E.; Mehari, Tadesse; Budambula, NancyEritrea has a number of hot springs whose physicochemical characteristics are not documented. This study examined the thermal and chemical features of five hot springs located in the eastern escarpment of Eritrea. Field data and water samples were collected from five hot springs namely; Akwar and Maiwooi near Gahtelai, Garbanabra and Gelti near Irafayle at the Gulf of Zula and Elegedi in Alid volcanic center. The water temperatures at source varied from 49.5°C to 100°C while pH levels ranged from 6.97 to 7.54. Elegedi had significantly higher temperature (p < 0.05) than the other four hot springs. Strong correlation was observed between electrical conductivity (EC), total dissolved solid (TDS), salinity, sodium, potassium, calcium and chloride (R2 > 0.9) as well as between temperature and sulphate levels (R2 = 0.96). Evident clustering was noted at p < 0.05, using Non-metric multidimensional scaling (NMDS), between the three locations of the hot springs. Akwar and Maiwooi, situated close to each other, clustered together, Garbanabra and Gelti, which were characterized by higher salinity levels, formed a separate cluster. Elegedi, characterized by high temperature (100°C), sulphate (979.7 mg/l) and NH4 + (196.33 mg/l) levels, clustered separately. Akwar and Maiwooi had high bicarbonate (345 mg/l and 393 mg/l) and fluoride (8.20 mg/l and 6.48 mg/l) levels which are above WHO limits. Electrical conductivity (23,133 mS/cm), total dissolved solid (15,552 mg/l), sodium (3,800 mg/l), potassium (198 mg/l), calcium (1,653 mg/l) and chloride (5,946 mg/l) levels in Garbanabra and Gelti hot springs exceeded WHO limits. Bromine (74.8 mg/l in Garbanabra and 45.2 mg/l in Gelti) and boron (2.21 mg/l in Garbanabra and 1.55 mg/l in Gelti) levels were also above standard limits set for potable water. Maiwooi (1.20) and Elegedi (1.10) were depositional while Akwar water (-0.71) was slightly corrosive. The corrosive nature of the water sample from Akwar, is a public health concern. The waters from the five Eritrean hot springs are thus not fit for human consumption. In addition, the use of thermal spring water for recreational purposes should be closely monitored.Item Screening for Water Deficit Tolerance, Relative Growth Analysis and Agrobacterium-Infectivity in Tropical Maize [Zea Mays L.] Inbred Lines in Nairobi, Kenya(2014-10) Sande, Olive F.; Njoka, Fredrick M.; Mgutu, Allan J.; Anami, Sylvester E.The gap between maize demand and regional supply is increasing as small-holder farmers grapple with many challenges, key among them drought. Research in identifying maize lines that are tolerant to water deficit and that are amenable to A. tumefaciens-mediated transformation is a step towards enhancing food security. The objectives of this study were, to assess the physiological response of tropical maize inbred lines to water deficit, to determine whether A. tumefaciens elicits host resistance when in contact with zygotic embryos and determine if YEP is an effective infection medium compared to MS medium in immature zygotic embryo infection. Tropical maize lines CML 395, CML 216, CML 144, TL 21, A 04, E 04 and T 04 and Agrobacterium strain EHA101 habouring pTF102 vector containing GUS reporter gene were used. Physiological response of tropical maize genotypes to drought stress was evaluated by measuring plant height, leaf length, leaf width and fresh weight. T 04 and CML 216 seedlings exhibited the fastest growth rates of 4.33 cm and 4.28 cm respectively between the 7th and 8th day post leaf four emergence while TL 21 and CML 395 seedlings had the lowest rates of 2.93 cm and 3.59 cm respectively under normal growth conditions. A 04 seedlings exhibited the highest differences in fresh weight between stressed and unstressed plants [56.13 gm] while CML 216 seedlings had the lowest [24.57 gm]. Upon salt stress, leaf discs of CML 216 seedlings, exhibited low chlorophyll a: b ratios of 0.84, 0.78, 0.74, 0.75 and 0.70 in 100 mM, 125 mM, 150 mM, 175 mM and 200 mM NaCl concentrations respectively, while leaf discs of CML 144 seedlings exhibited higher chlorophyll a: b ratios of 1.51, 1.19, 1.24, 1.26, 1.45 and 1.39 under the same concentrations. The use of YEP medium in contrast to MS medium led to an improvement in transient GUS expression observed in immature embryos and significant increase in transformation frequency. The transformation protocol using YEP infection media as used in this study should be optimized and used in transformation of tropical maize inbreds.Item Screening for Water Deficit Tolerance, Relative Growth Analysis and Agrobacterium-Infectivity in Tropical Maize [Zea Mays L.] Inbred Lines in Nairobi, Kenya(2014-10) Olive, Sande F.; Njoka, Fredrick M.; Mgutu, Allan J.; Anami, Sylvester E.The gap between maize demand and regional supply is increasing as small-holder farmers grapple with many challenges, key among them drought. Research in identifying maize lines that are tolerant to water deficit and that are amenable to A. tumefaciens-mediated transformation is a step towards enhancing food security. The objectives of this study were, to assess the physiological response of tropical maize inbred lines to water deficit, to determine whether A. tumefaciens elicits host resistance when in contact with zygotic embryos and determine if YEP is an effective infection medium compared to MS medium in immature zygotic embryo infection. Tropical maize lines CML 395, CML 216, CML 144, TL 21, A 04, E 04 and T 04 and Agrobacterium strain EHA101 habouring pTF102 vector containing GUS reporter gene were used. Physiological response of tropical maize genotypes to drought stress was evaluated by measuring plant height, leaf length, leaf width and fresh weight. T 04 and CML 216 seedlings exhibited the fastest growth rates of 4.33 cm and 4.28 cm respectively between the 7th and 8th day post leaf four emergence while TL 21 and CML 395 seedlings had the lowest rates of 2.93 cm and 3.59 cm respectively under normal growth conditions. A 04 seedlings exhibited the highest differences in fresh weight between stressed and unstressed plants [56.13 gm] while CML 216 seedlings had the lowest [24.57 gm]. Upon salt stress, leaf discs of CML 216 seedlings, exhibited low chlorophyll a: b ratios of 0.84, 0.78, 0.74, 0.75 and 0.70 in 100 mM, 125 mM, 150 mM, 175 mM and 200 mM NaCl concentrations respectively, while leaf discs of CML 144 seedlings exhibited higher chlorophyll a: b ratios of 1.51, 1.19, 1.24, 1.26, 1.45 and 1.39 under the same concentrations. The use of YEP medium in contrast to MS medium led to an improvement in transient GUS expression observed in immature embryos and significant increase in transformation frequency. The transformation protocol using YEP infection media as used in this study should be optimized and used in transformation of tropical maize inbreds.Item Screening for Water Deficit Tolerance, Relative Growth Analysis and Agrobacterium-Infectivity in Tropical Maize [Zea Mays L.] Inbred Lines in Nairobi, Kenya(2014-12) Olive, Sande F.; Njoka, Fredrick M.; Mgutu, Allan J; Anami, Sylvester E.The gap between maize demand and regional supply is increasing as small-holder farmers grapple with many challenges, key among them drought. Research in identifying maize lines that are tolerant to water deficit and that are amenable to A. tumefaciens-mediated transformation is a step towards enhancing food security. The objectives of this study were, to assess the physiological response of tropical maize inbred lines to water deficit, to determine whether A. tumefaciens elicits host resistance when in contact with zygotic embryos and determine if YEP is an effective infection medium compared to MS medium in immature zygotic embryo infection. Tropical maize lines CML 395, CML 216, CML 144, TL 21, A 04, E 04 and T 04 and Agrobacterium strain EHA101 habouring pTF102 vector containing GUS reporter gene were used. Physiological response of tropical maize genotypes to drought stress was evaluated by measuring plant height, leaf length, leaf width and fresh weight. T 04 and CML 216 seedlings exhibited the fastest growth rates of 4.33 cm and 4.28 cm respectively between the 7th and 8th day post leaf four emergence while TL 21 and CML 395 seedlings had the lowest rates of 2.93 cm and 3.59 cm respectively under normal growth conditions. A 04 seedlings exhibited the highest differences in fresh weight between stressed and unstressed plants [56.13 gm] while CML 216 seedlings had the lowest [24.57 gm]. Upon salt stress, leaf discs of CML 216 seedlings, exhibited low chlorophyll a: b ratios of 0.84, 0.78, 0.74, 0.75 and 0.70 in 100 mM, 125 mM, 150 mM, 175 mM and 200 mM NaCl concentrations respectively, while leaf discs of CML 144 seedlings exhibited higher chlorophyll a: b ratios of 1.51, 1.19, 1.24, 1.26, 1.45 and 1.39 under the same concentrations. The use of YEP medium in contrast to MS medium led to an improvement in transient GUS expression observed in immature embryos and significant increase in transformation frequency. The transformation protocol using YEP infection media as used in this study should be optimized and used in transformation of tropical maize inbreds.Item Thermotolerant bacteria of biotechnological potential from hot springs in Eritrea(2018-06) Ghilamicael, Amanuel M.; Budambula, Nancy; Anami, Sylvester E.; Mehari, Tadesse; Boga, Hamadi IddiThermophiles are excellent sources of enzymes that can withstand and carry out reactions efficiently under high temperatures. This study isolated and characterised thermotolerant bacteria that produce enzymes of potential industrial value from five hot springs in Eritrea. A total of 65 bacterial isolates were obtained from the five hot springs. Out of the 65 isolates; 19 isolates produced a positive reaction for amylases, 36 for carboxymethyl cellulases, eight for proteases, 10 for xylanases and 11 for pectinases. More than half (36 out of 65) were able to produce carboxymethyl cellulases. Six isolates which showed carboxymethyl cellulase activity were from the genus Bacillus, while those belonging to Brevibacillus were seven. BLAST analysis of the partial sequences showed that 19 out of the 24 isolates sequenced showed high similarity (> 99%) to those of reference strains of the genera Bacillus and Brevibacillus available in the Genebank and EZ-taxon databases. The five isolates (E5, G2, G8, M1 and M13) that showed moderate similarities (97.2-99%) to strains from the Genebank and EZ-taxon databases were further characterized. Physiological characterization of the five selected isolates based on tolerance to NaCl, temperature and production of hydrolytic enzymes indicated that these isolates are potentially novel. Isolates G8 and M13 showed significantly higher amylase activity (p < 0.05) than the other three isolates. Caseinase activity recorded by the five isolates was the highest (p < 0.05) compared to other enzyme activities. The enzymes produced by thermotolerant bacteria from the five hot springs may be potentially useful for catalysis under harsh operational conditions encountered in industrial processes.Item Yeast Extract Peptone Based Co-cultivation Media Promotes Transient GUS Expression in Tropical Maize Genotypes(2017) Muli, Joshua K.; Mweu, Cecilia; Budambula, Nancy; Anami, Sylvester E.Background and Objective: Tropical maize is the most cultivated crop in sub-Saharan Africa and is a staple food to over 220 million people. This study, evaluated the competence of four tropical maize (Zea mays L.) inbred lines to callus induction and regeneration through somatic embryogenesis when co-cultivated on yeast extract peptone medium (YEP). Materials and Methods: Transient GUS assay was used to evaluate the competence of the genotypes to Agrobacterium-mediated transformation using YEP as co-cultivation media or when YEP was supplemented with 2,4-D (YEP+2,4-D), cysteine (YEP+CYS), proline (YEP+PRO) or in combination (YEP+ALL). Data on all parameters were analyzed using multivariate ANOVA and SAS. Results: Co-cultivation media based on YEP alone did not impact callus induction and immature embryos exhibited preconscious germination. When YEP was supplemented with 2,4-D at concentrations 1.5 and 3 mg LG1 2,4-D, the formation of embryogenic calli was induced and regeneration initiated. Immature embryos had high transient GUS expression when co-cultivated with Agrobacterium on YEP, YEP+PRO and YEP+ALL media than when co-cultivated on MS media, suggesting that YEP promotes Agrobacterium-mediated integration of transgenes in tropical maize. Agrobacterium tumefaciens at a concentration of 0.07 (OD660) gave the highest transient GUS expression (20.90%) while concentrations of 0.8 and 0.2 resulted in low transient GUS expression (9.17 and 12.22%, respectively). Conclusion: The integration of YEP media in the Agrobacterium-mediated transformation protocols is likely to contribute in the development of a more efficient Agrobacterium-mediated transformation system for tropical maize genotypes.