Search

Magnaporthe oryzae, a devastating pathogen of finger millet (Eleusine coracana), secretes effector molecules during infection to manipulate host immunity. This study determined the presence of avirulence effector genes PWL1 and PWL2 in 221 Eleusine blast isolates from eastern Africa. Most Ethiopian isolates carried both PWL1 and PWL2. Kenyan and Ugandan isolates largely lacked both genes, and Tanzanian isolates carried either PWL1 or lacked both. The roles of PWL1 and PWL2 towards pathogenicity on alternative Chloridoid hosts, including weeping lovegrass (Eragrostis curvula), were also investigated. PWL1 and PWL2 were cloned from Ethiopian isolate E22 and transformed separately into Ugandan isolate U34, which lacked both genes. Resulting transformants harboring either gene gained varying degrees of avirulence on E. curvula but remained virulent on finger millet. Strains carrying PWL1 and/or PWL2 infected the Chloridoid species Sporobolus phyllotrichus and Eleusine tristachya, indicating the absence of cognate resistance (R) genes for PWL1 and PWL2 in these species. Other Chloridoid grasses, however, were fully resistant, regardless of the presence of PWL1 and/or PWL2, suggesting the presence of effective R genes against PWL and/or other effectors. Partial resistance in some E. curvula accessions to some blast isolates lacking PWL1 and PWL2 also indicated the presence of other AVR-R interactions. Related Chloridoid species thus harbour resistance genes that could be useful to improve finger millet for blast resistance. Conversely, loss of AVR genes in the fungus could expand its host range, as demonstrated by E. curvula’s susceptibility to finger millet blast isolates that had lost PWL1 and PWL2.

Finger millet blast caused by Pyricularia oryzae is the most globally important disease of finger millet. The disease ravages cultivated finger millet, posing a threat to one of the world’s most important, climate-resilient, and nutrient-rich cereal crops, which serves as an important source of food security. Both pathogenic and mutualistic fungi colonize plant tissues and compete for the same niche, subsequently influencing the disease pathogenesis. We analyzed the natural dynamics of the fungal community associated with finger millet blast. Fungal culture was performed on blast-diseased finger millet tissues collected from different agro-ecological regions in Kenya. Fifty-five isolates were obtained from finger, leaf and neck tissues with blast symptoms and characterized based on morphology and DNA sequencing of the internal transcribed spacer (ITS) and 28S rDNA regions. The identified fungal genera corresponded to Exserohilum, Sarocladium, Fusarium, Epicoccum, Cochliobolus, Curvularia, Bipolaris, Penicillium, Setosphaeria, Phoma, and Alternaria, in addition to two unnamed fungal species. Many fungal pathogens of other crops that are not inherently expected to be present on finger millet were encountered, including Penicillium citrinum. Multi-gene phylogenetic studies using concatenated sequences for the ITS and 28SrDNA regions were analyzed using IQ-tree on maximum likelihood basis and aligned using MAFFT to generate a tree with two distinct groups, which were further segregated into several subgroups. The outcome of this study provides useful information on the type of fungal community associated with finger millet blast, which may open avenues for understanding and protecting against finger millet blast disease in Kenya.

Improved agricultural production of essential crops through advanced breeding is important for increasing access to nutritious food for the world's rapidly growing population, which is expected to reach 9.8 billion by 2050. Recent advancements in the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein9 (CRISPR/Cas9) genome editing process, which uses single-guide RNA for genome editing, have made it easy, stable and efficient tool for targeted gene mutations, knockout and knock-in/replacement to boost crop yield. The CRISPR/Cas method is constantly being improved, and its applications have greatly expanded. It can be used to modify the genome sequence of any organism, including plants like cassava, to achieve the desired trait. As a result, CRISPR/Cas is regarded as a game-changing technology in plant biology. Here, we discuss the principles of operation, implementations and future prospects of CRISPR/Cas9 for efficient processing of individual genes in cassava cultures. Recent work on cassava crop with regards to the use of CRISPR/Cas9 for the plant improvement was also addressed. Key words: Manihot esculenta, CRISPR/Cas9, genome editing, gRNA, protospacer adjacent motif (PAM).

Friable embryogenic callus (FEC) currently forms the tissue of choice for gene transfer to cassava tissues. However, this technology has not been sufficiently adopted in most laboratories, partly because of the challenging protocols involved in FEC production. Therefore, the development of transformation systems targeting readily accessible explants could enable the rapid improvement of this essential root tuber. This study developed a simple, efficient, and rapid transformation protocol for three elite cassava cultivars (TMS 60444, 08/354, KME 1) using immature leaf lobes (ILLs). Factors affecting callus and somatic embryo formation, such as auxin concentration and culture photoperiod, were optimized. Cassava transformation was achieved by co-cultivation of ILLs and callus with Agrobacterium strain EHA101 harboring pTF102 plasmid. We report a positive interactive effect between dark treatment and an increasing auxin concentration. Exposure to light was found to negatively affect the formation and viability of SEs by promoting tissue browning. The results further show that cassava transformation success depends on the cultivar, explant type, and age. Using this simple protocol, transgenic plants of TMS 60444, 08/354, and KME 1 with an average transformation frequency of 0.4% (0.5, 0.4, and 0.4%, respectively) were obtained in 6 months. Reverse transcription PCR, Southern blot, and histochemical GUS staining confirmed the stable integration of the gusA gene into the regenerated plantlets. This optimized transformation system for cassava is rapid, efficient, and simple to operate and will facilitate more genetic applications in cassava research.

Groundnuts are among the principle economic oilseed largely cultivated in warm regions of Kenya and contribute to domestic food security and cash revenue. The study aimed at evaluating genetic diversity and phenotypic characterization of groundnut varieties grown in some parts of Kenya. Six varieties (ICG83708, ICGV99568, CG7, ICGV12991, RV and Chalimbana) obtained from KALRO (Kakamega) based on quality traits. Seeds were planted in cylindrical cans with 0.2 m3 of soil and allowed to germinate for 3 weeks. Leaf trait measurement was done using 15 cm ruler and the data was recorded in excel spreadsheet and exported to MINITAB v17 software. Extracted DNA was amplified using 11 SSR primers with manual scoring of bands. A dendrogram of cluster analysis was constructed based on simple matching coefficient of 11 microsatellite markers. Principle components showed Eigen values with 67.2% variability of all the traits studied. A total of 35 alleles were detected across the loci of 11 primers used. Major allele frequency ranged from 0.9333 in IPAHM 165 to the least frequency of 0.6333 in IPAHM 176 with an average of 0.7610 across all the markers. The expected heterozygosity had a mean of 0.3178 with highest value of 0.4511 in IPAHM 176. Phylogenetic tree had three major clusters and with high bootstrap values in genotype icgv99568 replicates. Primer IPAHM176 was the most informative marker and should be utilized in selection of parent plants with good quality traits. Breeding programs on groundnuts should utilize grain and seed traits since they are informative and discriminatory. Key words: Groundnut varieties, phenotypic and genetic characterization, gene diversity.

Finger millet is an important cereal that is grown in semi-arid and arid regions of East-Africa. Salinity stress is a major environmental impediment for the crop growth and production. This study aimed to understand the physiological and biochemical responses to salinity stress of six Kenyan finger millet varieties (GBK043137, GBK043128, GBK043124, GBK043122, GBK043094, GBK043050) grown across different agroecological zones under NaCl-induced salinity stress (100, 200 and 300 mM NaCl). Seeds were germinated on the sterile soil and treated using various concentrations of NaCl for 2 weeks. Early-seedling stage of germinated plants were irrigated with the same salt concentrations for 60 days. The results indicated depression in germination percentage, shoot and root growth rate, leaf relative water content, chlorophyll content, leaf K(+) concentration, and leaf K(+)/Na(+) ratios with increased salt levels and the degree of increment differed among the varieties. On the contrary, the content of proline, malonaldehyde, leaf total proteins, and reduced sugar increased with increasing salinity. At the same time, the leaf Na(+) and Cl(−) amounts of all plants increased substantially with increasing stress levels. Clustering analysis placed GBK043094 and GBK043137 together and these varieties were identified as salt-tolerant based on their performance. Taken together, our findings indicated a significant varietal variability for most of the parameters analysed. The superior varieties identified could be used as promising genetic resources in future breeding programmes directed towards development of salt-tolerant finger millet hybrids. Further analysis at genomic level needs to be undertaken to better understand the genetic factors that promote salinity tolerance in finger millet. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12298-020-00853-8) contains supplementary material, which is available to authorized users.

Finger millet is a food crop that provides nutritional security and is climatically resilient for farming and agricultural diversification. However, its quality and yield remain low due to biotic and abiotic factors, the greatest of which is blast disease caused by Magnaporthe oryzae. We surveyed the occurrence, distribution and severity of finger millet blast in five counties, namely, Busia, Bungoma, Kisii, Machakos and Makueni, in Kenya. Blast disease occurrence was determined by observing disease symptoms of different plant parts on each farm, and symptoms were recorded as either present or absent. Severity was evaluated based on the disease symptoms on plant fingers, leaves and necks and generally at the whole farm scale. Distribution was assessed based on the number of farms sampled for blast per county, and global positioning systems coordinates were recorded. Blast occurrence was 100%, with a uniform distribution pattern on all the farms surveyed across all the counties. Busia County had the highest disease severity at 82.3%, while Makueni had the lowest severity at 61%. Pearson’s correlation test revealed no statistically significant correlation between blast severity and plant parts infected (p< 0.05), with Busia (74.2%) having the highest number of plants showing symptoms of blast on fingers, followed by Bungoma (57.1%), Makueni (57%), Machakos (56%) and Kisii, 53.3%. This study reveals that finger millet blast is rampant in all the counties surveyed and is widely distributed in Kenya. This information is helpful in understanding the geographical distribution, occurrence and severity of M. oryzae. Key words: Finger millet blast, occurrence, severity, distribution, Magnaporthe oryzae.

Salinity is among the most severe and widespread environmental constrains to global crop production, especially in arid and semi-arid climates and negatively affecting productivity of salt sensitive crop species. Breeding and selection of salt tolerant crop varieties is therefore necessary for sustainable plant productivity. Given that germination and seeding phases are the most critical phase in the plant life cycle, this study aimed to evaluate seed germination potential and associated traits under salt stress conditions as a simple approach to identify salt tolerant sorghum varieties [Gadam, Sc Sila and Serena] which are adaptated to various agroecological regions. Salinity stress was applied by addition of NaCl at three different levels of stress [100, 200 and 300 mM NaCl], while plants irrigated with water were used as control. Evaluation of tolerance was performed on the basis of germination percentage, shoot and seed water absorbance, shoot and root length, leave water content, seedling total chlorophyll content and morphologic abnormality. Our results showed that salinity stress significantly impacts all features associated with germination and early development of seedlings. Our results indicated that salinity stress substantially affects all traits associated with germination and early seedling growth, with the effect of salinity being dependent on the variety used and level of salinity stress applied. Among the tested sorghum varieties, Gadam was established to the most salt tolerant variety, suggesting its potential use for cultivation under salinity stress conditions as well as its suitability for use as germplasm material in future sorghum breeding programmes. For a greater insight into comprehensive mechanisms of salinity tolerance in sorghum, we suggest further research on genomic and molecular analysis.

Calotropis procera it is known for traditional Kenyan medicinal system and it is used for it has previously been employed for treatment various diseases. This study aimed at examining methanolic extract of C. procera to establish antioxidant potential in vitro, total phenolic and flavonoid contents in order to identify potential sources of new antioxidants in food and pharmaceutical formulations. A comprehensive assessment on the antioxidant activity of stem back and root of C. procera by in vitro chemical analyses. Total phenolic, total flavonoid contents and total yield of the samples were also estimated. Preliminary phytochemical tests were also carried out to establish the components of plant extracts. Results of the study revealed presence of saponins terpenoids, alkaloids, anthraquinones and steroids. The stem back extract had significantly higher amounts of total phenol and flavonoid contents (79.80 ± 3.79 mg GAE/g extract and 71.63±4. mg RTE/g extract, respectively) compared to root samples. We established correlation between total phenolic contents and EC50 values for DPPH free radical scavenging property and reducing power of extract, ABTS radical cation and phosphomolybdate. Taken together, this work demonstrated considerable protective effectiveness in C. procera stem back and root methanolic extracts that function as an antioxidizing agent due to their free radical scavenging activity.

Background Treatment of gonorrhea is complicated by the development of antimicrobial resistance in Neisseria gonorrhoeae (GC) to the antibiotics recommended for treatment. Knowledge on types of plasmids and the antibiotic resistance genes they harbor is useful in monitoring the emergence and spread of bacterial antibiotic resistance. In Kenya, studies on gonococcal antimicrobial resistance are few and data on plasmid mediated drug resistance is limited. The present study characterizes plasmid mediated resistance in N. gonorrhoeae isolates recovered from Kenya between 2013 and 2018. Methods DNA was extracted from 36 sub-cultured GC isolates exhibiting varying drug resistance profiles. Whole genome sequencing was done on Illumina MiSeq platform and reads assembled de-novo using CLC Genomics Workbench. Genome annotation was performed using Rapid Annotation Subsystem Technology. Comparisons in identified antimicrobial resistance determinants were done using Bioedit sequence alignment editor. Results Twenty-four (66.7%) isolates had both β-lactamase (TEM) and TetM encoding plasmids. 8.3% of the isolates lacked both TEM and TetM plasmids and had intermediate to susceptible penicillin and tetracycline MICs. Twenty-six (72%) isolates harbored TEM encoding plasmids. 25 of the TEM plasmids were of African type while one was an Asian type. Of the 36 isolates, 31 (86.1%) had TetM encoding plasmids, 30 of which harbored American TetM, whereas 1 carried a Dutch TetM. All analyzed isolates had non-mosaic penA alleles. All the isolates expressing TetM were tetracycline resistant (MIC> 1 mg/L) and had increased doxycycline MICs (up to 96 mg/L). All the isolates had S10 ribosomal protein V57M amino acid substitution associated with tetracycline resistance. No relation was observed between PenB and MtrR alterations and penicillin and tetracycline MICs. Conclusion High-level gonococcal penicillin and tetracycline resistance in the sampled Kenyan regions was found to be mediated by plasmid borne blaTEM and tetM genes. While the African TEM plasmid, TEM1 and American TetM are the dominant genotypes, Asian TEM plasmid, a new TEM239 and Dutch TetM have emerged in the regions.

A simple and efficient plant regeneration system via direct organogenesis was established in finger millet using in vitro derived shoot apical meristems. Six varieties; GBK-043128, GBK-043094, GBK-043050, GBK-043137, GBK-043122 and GBK-043124 were evaluated. MS medium was used for cotyledonary germination. Maximum number of shoots (84.33%) was observed in variety GBK-043128 while GBK-043094 had the least germination efficiency (62. 67%). Shoot apical meristems from three-day old seedlings were evaluated for their potency of shoot induction on varied 6-benzylaminopurine (BAP) concentrations. Highest shoot induction was observed in medium supplemented with 1.75 mg/l BAP in GBK-043050 (3.00) whereas GBK-043094 (1.28) had the least response in medium supplemented with 1.0 mg/l BAP. To induce rooting, in vitro regenerated plants cultured on MS medium was supplemented with different concentrations of indole-3- acetic acid. The highest response in root induction, with a larger number of roots (10.28), was observed in MS medium supplemented with 4.0 µM IAA. Statistical analysis indicated that plant regeneration response varied greatly among the varieties. In vitro germinated plants were successfully transferred to the greenhouse after hardening, with 300 shoots developing into fertile plants, which were indistinguishable with wild type plants. This plant regeneration system has potential for production of transgenic finger millet crops. Key words: Direct organogenesis, finger millet, root induction, shoot apical meristems.

The plant of the species Caesalpinia volkensii has diverse traditional use. This review aims at providing an overview of the plants traditional utility and scientific potential in managing both infectious and lifestyle diseases. It focuses on the plants hypoglycaemic activity, anti-malarial, anti-nociceptive and anti-inflamatory activity. The review also looks at the antimicrobial property of the plant, phytochemical analysis and safety.

In the present study, an efficient protocol for somatic embryogenesis and plant regeneration was established in six finger millet varieties (GBK-043137, GBK-043128, GBK-043124, GBK-043122, GBK-043094 and GBK-043050). Shoot tips from 3 days in vitro grown plants were inoculated on MS supplemented with various concentrations and combinations of α-naphthaleneacetic acid (NAA), 2,4-Dichlorophenoxyacetic acid (2,4-D), benzylaminopurine (BAP) and kinetin for callus induction and somatic embryogenesis. For shoot regeneration, somatic embryos were cultured on various concentrations of BAP, while root induction was done using different concentrations and combinations of NAA, kinetin, BAP and 2,4-D. Acclimatization of regenerated plants was tested using forest soil, cocopeat, manure, sand and fertilizer either singly or in combination. Best callus formation was achieved on 2.5 mg/l of 2,4-D and 1.5 mg/l BAP with a mean of 12.33±0.33 on variety GBK-043128 while shooting and rooting were best on 1.75 mg/l BAP with a mean of 25.07±0.64 and 1.0 BAP+0.25 NAA with a mean of 15.00±2.2, respectively. Best acclimatization was attained using soil, sand and fertilizer on GBK-043094. Plants regenerated were morphologically similar to in vivo plants with 97% survival rate. Moreover, they were fertile and able to set viable seeds. This efi¬cient protocol has the potential for crop improvement and genomic studies. Key words: Finger millet, plant regeneration, shoot tips, somatic embryogenesis.

Drought stress often leads to reduced yields and is a perilous delimiter for expanded cultivation and increased productivity of sweet potato. Cell wall stabilization proteins have been identified to play a pivotal role in mechanical stabilization during desiccation stress mitigation in plants. They are involved in numerous cellular processes that modify cell wall properties to tolerate the mechanical stress during dehydration. This provides a plausible approach to engineer crops for enhanced stable yields under adverse climatic conditions. In this study, we genetically engineered sweet potato cv. Jewel with XvSap1 gene encoding a protein related to cell wall stabilization, isolated from the resurrection plant Xerophyta viscosa, under stress-inducible XvPSap1 promoter via Agrobacterium-mediated transformation. Detection of the transgene by PCR, Southern blot, and quantitative real-time PCR (qRT-PCR) analyses revealed the integration of XvSap1 in the three independent events. Phenotypic evaluation of shoot length, number of leaves, and yield revealed that the transgenic plants grew better than the wild-type plants under drought stress. Assessment of biochemical indices during drought stress showed higher levels of chlorophyll, free proline, and relative water content and decreased lipid peroxidation in transgenic plants than in wild types. Our findings demonstrate that XvSap1 enhances drought tolerance in transgenic sweet potato without causing deleterious phenotypic and yield changes. The transgenic drought-tolerant sweet potato lines provide a valuable resource as a drought-tolerant crop on arid lands of the world.

Salinity is among the most severe and widespread environmental constrains to global crop production, especially in arid and semi-arid climates and negatively affecting productivity of salt sensitive crop species. Breeding and selection of salt tolerant crop varieties is therefore necessary for sustainable plant productivity. Given that germination and seeding phases are the most critical phase in the plant life cycle, this study aimed to evaluate seed germination potential and associated traits under salt stress conditions as a simple approach to identify salt tolerant Sorghum varieties. There Sorghum varieties whose adaptation to various agroclimatic conditions is not well elucidated. Salinity stress was applied by addition of NaCl at three different levels of stress (100, 200 and 300 mM NaCl), while plants irrigated with water were used as controls. Evaluation of tolerance was performed on the basis of germination percentage, shoot and seed water absorbance, shoot and root length, leave water content, seedling total chlorophyll content and morphologic abnormality. Our results showed that salinity stress significantly impacts all features associated with germination and early development of seedlings. Our results indicated that that salinity stress substantially affects all traits associated with germination and early seedling growth, with the effect of salinity being dependent on the variety used and level of salinity stress applied. Among the tested Sorghum varieties, Gadam was established to the most salt tolerant variety, suggesting its potential use for cultivation under salinity stress conditions as well as its suitability for use as germplasm material in future Sorghum breeding programmes. For a greater insight into comprehensive mechanisms of salinity tolerance in Sorghum, we suggest further research on genomic and molecular analysis.

Background Phenotypic fluoroquinolone resistance was first reported in Western Kenya in 2009 and later in Coastal Kenya and Nairobi. Until recently gonococcal fluoroquinolone resistance mechanisms in Kenya had not been elucidated. The aim of this paper is to analyze mutations in both GyrA and ParC responsible for elevated fluoroquinolone MICs in Neisseria gonorrhoeae (GC) isolated from heterosexual individuals from different locations in Kenya. Methods Antimicrobial Susceptibility Tests were done on 84 GC in an ongoing STI surveillance program. Of the 84 isolates, 22 resistant to two or more classes of antimicrobials were chosen for analysis. Antimicrobial susceptibility tests were done using E-test and the results were interpreted with reference to European Committee on Antimicrobial Susceptibility Testing (EUCAST) standards. The isolates were sub-cultured and whole genomes sequenced using Illumina platform. Reads were assembled de novo using Velvet, and mutations in the GC Quinolone Resistant Determining Regions identified using Bioedit sequence alignment editor. Single Nucleotide Polymorphism based phylogeny was inferred using RaxML. Results Double GyrA mutations; S91F and D95G/D95A were identified in 20 isolates. Of these 20 isolates, 14 had an additional E91G ParC mutation and significantly higher ciprofloxacin MICs (p=0.0044*). On the contrary, norfloxacin MICs of isolates expressing both GyrA and ParC QRDR mutations were not significantly high (p=0.82) compared to MICs of isolates expressing GyrA mutations alone. No single GyrA mutation was found in the analyzed isolates, and no isolate contained a ParC mutation without the simultaneous presence of double GyrA mutations. Maximum likelihood tree clustered the 22 isolates into 6 distinct clades. Conclusion Simultaneous presence of mutations in ParC and GyrA has been reported to increase gonococcal fluoroquinolone resistance from different regions in the world. Our findings indicate that GyrAS91F, D95G/D95A and ParC E91G amino acid substitutions mediate high fluoroquinolone resistance in the analyzed Kenyan GC. Disclosure No significant relationships.

Drought is the most perilous abiotic stress that affects finger millet growth and productivity worldwide. For the successful production of finger millet, selection of drought tolerant varieties is necessary and critical stages under drought stress, germination and early seedling growth, ought to be fully understood. This study investigated the physiological and biochemical responses of six finger millet varieties (GBK043137, GBK043128, GBK043124, GBK043122, GBK043094 and GBK043050) under mannitol-induced drought stress. Seeds were germinated on sterile soil and irrigated with various concentrations of mannitol (200, 400 and 600 mM) for two weeks. Comparative analysis in terms of relative water content (RWC), chlorophyll, proline, and malondialdehyde (MDA) contents were measured the physiological and biochemical characteristics of drought stress. The results showed that increased level of drought stress seriously decreased germination and early seedling growth of finger millet varieties. However, root growth was increased. In addition, exposition to drought stress triggered a significant decrease in relative water content and chlorophyll content reduction the biochemical parameters assay showed less reduction of relative water content. Furthermore, oxidative damage indicating parameters such as proline concentration and MDA content increased. Varieties GBK043137 and GBK043094 were less affected by drought as shown by significant change in the physiological parameters. Our findings reveal the difference and linkage between the physiological responses of finger millet to drought and are vital for breeding and selection of drought tolerant varieties of finger millet. Further investigations on genomic and molecular to deeply insight the detail mechanisms of drought tolerance in finger millet need to explored.

Key message Drought stress in sweetpotato could be overcome by introducing XvSap1 gene from Xerophyta viscosa.Drought stress often leads to reduced yields and is perilous delimiter for expanded cultivation and increased productivity of sweetpotato. Cell wall stabilization proteins have been identified to play a pivotal role in mechanical stabilization during desiccation stress mitigation. They are involved in myriad cellular processes that modify the cell wall properties to tolerate the mechanical stress during dehydration in plants. This provides a possible approach to engineer crops for enhanced stable yields under adverse climatic conditions. In this study, we introduced the XvSap1 gene isolated from Xerophyta viscosa, a resurrection plant into sweetpotato by Agrobacterium-mediated transformation. Detection of the transgene by PCR coupled with Southern blot revealed the integration of XvSap1 in the three independent events. Sweetpotato plants expressing the XvSap1 gene exhibited superior growth performance such as shoot length, number of leaves and yield than the wild type plants under drought stress. Quantitative real time-PCR results confirmed higher expression of the XvSap1 gene in XSP1 transgenic plants imposed with drought stress. In addition, the transgenic plants had increased levels of chlorophyll, free proline and relative water content but malonaldehyde content was decreased under drought stress compared to wild type plants. Conjointly, our findings show that XvSap1 can enhance drought resilience without causing deleterious phenotypic and yield changes, thus providing a promising candidate target for improving the drought tolerance of sweetpotato cultivars through genetic engineering. The transgenic drought tolerant sweetpotato line provides a valuable resource as drought tolerant crop on arid lands of the world.

Background Phenotypic fluoroquinolone resistance was first reported in Western Kenya in 2009 and later in Coastal Kenya and Nairobi. Until recently gonococcal fluoroquinolone resistance mechanisms in Kenya had not been elucidated. The aim of this paper is to analyze mutations in both gyrA and parC responsible for elevated fluoroquinolone Minimum Inhibitory Concentrations (MICs) in Neisseria gonorrhoeae (GC) isolated from heterosexual individuals from different locations in Kenya between 2013 and 2017. Methods Antimicrobial Susceptibility Tests were done on 84 GC in an ongoing Sexually Transmitted Infections (STI) surveillance program. Of the 84 isolates, 22 resistant to two or more classes of antimicrobials were chosen for analysis. Antimicrobial susceptibility tests were done using E-test (BioMerieux) and the results were interpreted with reference to European Committee on Antimicrobial Susceptibility Testing (EUCAST) standards. The isolates were sub-cultured, and whole genomes were sequenced using Illumina platform. Reads were assembled de novo using Velvet, and mutations in the GC Quinolone Resistant Determining Regions identified using Bioedit sequence alignment editor. Single Nucleotide Polymorphism based phylogeny was inferred using RaxML. Results Double GyrA amino acid substitutions; S91F and D95G/D95A were identified in 20 isolates. Of these 20 isolates, 14 had an additional E91G ParC substitution and significantly higher ciprofloxacin MICs (p = 0.0044*). On the contrary, norfloxacin MICs of isolates expressing both GyrA and ParC QRDR amino acid changes were not significantly high (p = 0.82) compared to MICs of isolates expressing GyrA substitutions alone. No single GyrA substitution was found in the analyzed isolates, and no isolate contained a ParC substitution without the simultaneous presence of double GyrA substitutions. Maximum likelihood tree clustered the 22 isolates into 6 distinct clades. Conclusion Simultaneous presence of amino acid substitutions in ParC and GyrA has been reported to increase gonococcal fluoroquinolone resistance from different regions in the world. Our findings indicate that GyrA S91F, D95G/D95A and ParC E91G amino acid substitutions mediate high fluoroquinolone resistance in the analyzed Kenyan GC.

Sweetpotato is a significant crop which is widely cultivated particularly in the developing countries with high and stable yield. However, drought stress is a major limiting factor that antagonistically influences the crop’s productivity. Dehydration stress caused by drought causes aggregation of reactive oxygen species (ROS) in plants, and aldose reductases are first-line safeguards against ROS caused by oxidative stress. In the present study, we generated transgenic sweetpotato plants expressing aldose reductase, XvAld1 isolated from Xerophyta viscosa under the control of a stress-inducible promoter via Agrobacterium-mediated transformation. Our results demonstrated that the transgenic sweetpotato lines displayed significant enhanced tolerance to simulated drought stress and enhanced recuperation after rehydration contrasted with wild-type plants. In addition, the transgenic plants exhibited improved photosynthetic efficiency, higher water content and more proline accumulation under dehydration stress conditions compared with wild-type plants. These results demonstrate that exploiting the XvAld1 gene is not only a compelling and attainable way to improve sweetpotato tolerance to drought stresses without causing any phenotypic imperfections but also a promising gene candidate for more extensive crop improvement.

Sweetpotato (Ipomoea batata) is an important, nutritionally rich vegetable crop, but severely affected by environmental stresses, pests and diseases which cause massive yield and quality losses. Genetic manipulation is becoming an important method for sweetpotato improvement. In the present study, a reproducible and highly efficient protocol for in vitro plant regeneration of six Kenyan farmer preferred sweetpotato, Enaironi, KEMB 36, KSP36, Mugande, Kalamb nyerere, SPK 013 and SPK004 through direct shoot organogenesis from stem internodes explants was developed. The results revealed that Kalamb nyerere had the highest number of adventitious bud; for light (5.33 and 4.33) and dark (8.00 and 5.00) induction condition for all TDZ hormone level (0.25 mg/l and 0.15 mg/l). When explants incubated in 0.10 mg/l NAA the regeneration frequencies were the highest at 83.33% (Jewel) and 96.67% (Kalamb nyerere) for adventitious buds recovered from light and darkness respectively. This was the optimal auxin concentration which gave the maximum regeneration frequency with adventitious buds recovered from the dark. The best Kenyan sweetpotato genotypes for direct shoot organogenesis were Kalamb nyerere, Kemb 36 and SPK 004. The protocol presented in this work is suitable for improvement of sweetpotato genotypes through tissue culture methods and or genetic transformation.

In response to increased public concern on antibiotic or herbicide resistance genes usage in genetically modified plants, mannose was evaluated as selectable agent for the genetic transformation of sweetpotato. Nontransformed sweetpotato stem explants of cv. KSP36 were cultured on media containing various combinations and concentrations sucrose and mannose ranging from 0 to 30 g/l. Likewise, efficacy of hygromycin and kanamycin as selection agents for transformation of sweetpotato was evaluated on media containing varying concentrations of antibiotics ranging 0 to 100 mg/l. Selection agent effectiveness was determined by detecting the minimal concentration of the selection agent required to fully inhibit sweetpotato calli growth. Hygromycin was the most effective selection agent as it inhibited cell growth at concentrations above 20 mg/l. Kanamycin was moderately effective as it inhibited cell growth at 60 mg/l. Sweetpotato calli were able to grow and even produce embryos even when mannose was the only source of carbohydrates.DOI: http://dx.doi.org/10.3126/ijls.v9i3.12466 International Journal of Life Sciences 9 (3): 2015; 46-53

The main objective of this study was to evaluate the in vivo toxicity of methanolic leaf extract of Vernonia lasiopus. To provide information on the safety of V. lasiopus, we evaluated its acute and sub-chronic toxicity in Wistar rats. For evaluation of acute toxicity of the plant extract, five Wistar rats were orally dosed with 2000 mg/kg body weight sequentially. Sub-chronic toxicity was tested in twenty Wistar rats using three extract doses 100, 300 and 1000 mg/kg body weight. They were orally administered for 28 days. Mortality and toxicity signs were monitored during the study period. At the end of the experiment, the animals were sacrificed, their internal organs weighed and blood samples collected for haematology and biochemical analysis. In acute toxicity, no single death was reported; leading to conclusion that the median lethal dose (LD50) of methanolic leaf extract of V. lasiopus is beyond 2000 mg/kg body weight. In sub-chronic toxicity studies, V. lasiopus lowered total proteins in all the study groups significantly. Albumin was also lowered at extract dose of 1000 mg/kg body weight. In addition, it resulted to significant neutropenia, lymphocytosis and thrombocytosis in the group administered with dose extract of 1000 mg/kg body weight (PA‹Â‚0.05). It was therefore concluded that methanolic leaf extract of V. lasiopus is safe for use when administered at therapeutic doses. The plant extract may also be useful in the management of haematological disorders especially thrombocytopenia.

Medicinal plant Caesalpinia volkensii is used to treat Malaria, conjunctivitis, retinoblastoma, and eyelid swelling as well as gonorrhoea and bilharzia. Animal toxicity information on this plant is limited. This medicinal plant was collected in Embu County in Kenya to evaluate its Acute and sub-chronic toxicity using Wistar rats. The rats were orally administered with different doses of the plants extracts. They were weighed on first day and after every 7 days during treatment with the extract. Signs of toxicity were also observed. After 28 days, the rats were sacrificed and blood samples taken for full hemogram, renal and liver function tests. Weight of internal organs was also recorded. Data was analysed using Minitab statistical software version 17. In acute toxicity studies, C. volkensii extracts did not result to death at extract dose of 2000 mg/kg body weight. In sub-chronic toxicity studies, there was no significance difference in body weight and organ weight among the groups treated with the plant extract (p>0.05). Treatment with extract dose of 1000 mg/kg body weight resulted in significant increase in total bilirubin and aspartate aminotransferase (PE‚0.05). In addition, 100 mg/kg body weight resulted in significant decrease in haemoglobin and haematocrit. Qualitative phytochemical screening confirmed the presence of various phytochemicals which have the ability to protect erythrocytes from oxidative damage as well as erythropoietin stimulatory activities. It was therefore concluded that methanolic leaf extract of C. volkensii is safe for acute oral administration. However, care should be exercised in sub-chronic exposure at 1000 mg/kg body weight and above to avoid liver injury.

Background: The barks of the medicinal plant, Terminalia brownii, are widely used in African folk medicine for the management of pain. However, this ethno-medicinal allegation has not been scientifically validated. This study was therefore designed to verify the antinociceptive potential of the methanolic bark extract of T. brownii in Wistar rats (Rattus novegicus). Methods: Fresh barks of T. brownii were obtained from Kitui County, Kenya with the guidance of a residential herbalist. The study used thirty 2-3 months old male Wistar rats, weighing 140-150 g. The rats were randomly divided into 6 groups; three control groups (normal, negative and positive) and three experimental groups (50, 100 and 150 mg/kg extract treatment). Each group had five rats. The analgesic properties of the extract were evaluated on formalin-induced pain and diclofenac was used as the standard drug. Results: The methanolic bark extracts of T. brownii demonstrated significant antinociceptive activity (p

Sweetpotato is an important food crop in the world as well as in Kenya. Various fungal, and viral diseases are major constraints in its production and are currently threatening the sweetpotato production in sub-Saharan Africa. Genetic engineering offers significant potential for the crop’s genetic improvement. However, this is limited by the low efi¬Âciency and strong genotype dependency in tissue culture. This study aimed to establish an efficient somatic embryogenesis and plant regeneration system using shoot apical meristem explants of sweetpotato. Three sweetpotato cultivars that are widely grown in Kenya; KSP36, Kemb36 and Mweu mutheke along with an exotic model cultivar Jewel were evaluated. The maximum somatic embryogenic induction, at 96.72%, was obtained from explants cultured on Linsmaier and Skoog salts and vitamins medium supplemented with 0.5 mg/l dichlorophenoxyacetic acid and 0.2 mg/l zeatin riboside. The highest number of shoot induction (33) was observed after transfer of embryonic callus to embryo maturation medium supplemented with 2 mg/l abscisic acid. Significant differences were observed between cultivars for somatic embryogenesis and plant regeneration. Jewel showed the best response, while Mweu mutheke was the least responsive under the culture conditions tested in this study. Regenerated plants were successfully rooted and grown to maturity after hardening in soil in the greenhouse. Such a robust, successful and efi¬Âcient system possesses the potential to become an important tool for crop improvement and functional studies of genes in sweetpotato.

The conventional drugs used to manage fever are usually not affordable, not easily available and have adverse side effects. Alternative therapeutic agents, like medicinal plant derivatives, should therefore be developed because they have been reported to be more affordable, more readily available and have lesser side effects. Terminalia brownii is traditionally used to manage fever but this ethno-medicinal claim lacks scientific validation. The present study therefore evaluated the anti-pyretic activity of T. brownii in Wistar rats. Fresh bark samples of T. brownii were collected from Kitui County, Kenya. This study used 30 adult male Wister rats that were 2-3 months old and weighing 140-180 g was used for the experiments. Steam-distilled turpentine was the pyrogen used to induce pyrexia and Aspirin was used as the reference drug. The extract reduced the elevated rectal temperatures by between 1.15-4.38% while aspirin reduced the elevated rectal temperatures by between 0.00-4.85%. The present study showed a significant dose-dependent anti-pyretic activity of methanolic bark extracts of T. brownii hence validating its folklore use as a fever remedy.