Biological Sciences

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A botanical inventory and diversity assessment of Mt. Marsabit forest, a sub-humid montane forest in the arid lands of northern Kenya
(Blackwell Publishing Ltd, 2007) Githae, Eunice W. 1,2; Chuah-Petiot, Mins 2; Mworia, John K. 2; Odee, David W. 1*
A botanical inventory and diversity of trees, shrubs (‡5 cm diameter at breast height [dbh]), herbs, climbers and lianas was assessed in plots (154) of 20 · 5 m in Mt. Marsabit forest, northern Kenya. We recorded 52 species of trees and shrubs, twelve species of herbs and six species of climbers and lianas. They belonged to 35 families and 64 genera. Rubiaceae was the richest family with nine species followed by Euphorbiaceae (six), Oleaceae (five), Rutaceae (four), Capparaceae, Labiatae and Leguminosae (three each). The rest of the families were represented by one or two species. Rinorea convallarioides (Bak.f.) Eyles ssp. Marsabitensis Grey-Wilson (Violaceae), an endemic species, and Drypetes gerrardii Hutch. (Euphorbiaceae), were the two most important species, accounting for more than third of the combined importance value. Species diversity indices were 2.735 (Shannon–Wiener), 0.88 (Simpson’s) and 0.296 (Evenness). There was a strong evidence of disturbance arising from anthropogenic and wildlife foraging activities. This inventory has affirmed Mt. Marsabit forest as a unique habitat for several endemic, rare, threatened or vulnerable plant species, which should be conserved.
Soil physicochemical properties under Acacia senegal varieties in the dryland areas of Kenya
(2011-08) Eunice, G. W.; Charles, K.K.; Jesse, T. N.
Acacia senegal is a multipurpose drought-tolerant tree or shrub legume and is commonly used in agroforestry systems in sub-Saharan Africa for gum arabic production and soil fertility improvement. Despite its wide distribution in Kenya, there has not been exhaustive evaluation on the effects of the extant varieties (kerensis, leiorhachis and senegal) on soil properties under their canopies for sustainable utilization of the species. Three sites in the drylands of Kenya representing the three varieties were selected for assessment. Soil samples were collected under tree canopies at a depth of 0 to 25 cm and were compared with the soils from the open canopies. There were significant differences in soil physicochemical properties among the three varieties (P< 0.01). Soil nutrients under the canopies were higher than in the open canopies mainly due to effects of litter accumulation. The three varieties have beneficial effects on soil nutrient status in their natural ecosystems and would most likely improve crop productivity in agroforestry systems as well as enhance herbage productivity in the rangelands. The varieties growing under different soil types may have an effect on their gum Arabic production and quality.
Effects of Auxin and Source of Explants on Callus Induction of Tropical Maize
(2012) Omer, Rasha Adam; Matheka, Jonathan M.; uno, Steven R.; li, bdelbagi M. A; Kuria, Eric; Masiga, Clet; Mugoya, Charles; Machuka, Jesse
Induction of callus from explants is a critical process in regeneration, micropropagation and transformation of plants. Formation of callus from plant tissues on culture is affected by different factors. This study sought to establish the effect of genotype, source of explants and auxin concentration on callus induction from different Sudanese maize genotypes (222F, Hudiba-1, 441, Giza-2, PR5655 and Mojtamma-45). Callus induction of the six maize varieties was investigated using mature embryos, leaf disks and shoot tips as explants and different concentrations of the auxin; 2,4-dichlorophenoxyacetic acid (2,4-D), ranging from 0 to 10 mg L-1. The highest callus, induction frequency was observed in shoot tips while the lowest was observed in mature embryos. Leaf disks gave a higher callus induction frequency than mature embryos and lower than shoot tips. Concentrations of 2,4-D of 2 mg L-1 gave the highest callus induction for most genotypes while 0 and 10 mg L-1 gave the lowest callus induction for all the genotypes.
Nitrogen Fixation by Natural Populations of Acacia Senegal in the Drylands of Kenya Using 15N Natural Abundance
(Taylor and Francis Online, 2013-06-24) Githae, Eunice W.; Gachene, Charles K.K.; Njoka, Jesse T.; Omondi, Stephene F.
Nitrogen (N) fixation was estimated for three Acacia senegal (L.) (A. senegal) Willd. varieties (A. senegal var. senegal, kerensis, and leiorhachis) growing naturally in different sites in the dryland areas of Kenya. The quantities of N2 fixed were estimated by the 15N natural abundance method, using leaves as the sampling material. Balanites aegyptiaca (B. aegyptiaca) was selected as the reference species growing in the same area. Soil samples were also collected under A. senegal trees for nodule assessment. Leaf 15N natural abundance values (δ15N) were significantly different between A. senegal and B. aegyptiaca. These values averaged 6.35, 4.67, and 3.03% for A. senegal var. kerensis, leiorhachis, and senegal, respectively, and were lower than those of the adjacent reference species. There were also significant differences in the amount of N2 fixed (% Ndfa) among the varieties. A. senegal var. senegal showed the highest levels of N2 fixation with a mean of 36% while A. senegal var. kerensis and leiorhachis had equal estimates of 25%. However, no nodules were observed in the collected soil samples. Leaf N values were significantly different among the varieties with a mean of 2.73, 2.46, and 4.03% for A. senegal var. kerensis, leiorhachis, and senegal, respectively. This study shows that the three varieties of A. senegal are able to fix N2 in their natural ecosystems and the differences could probably be due to soil properties and nutrient availability under the different environments. The species can hence be utilized as plantations in agriculture and land rehabilitation programs.
Parasites of Commercially Important Fish from Lake Naivasha, Rift Valley, Kenya.
(springer, 2014-01) Otachi, Elick; Magana, Adiel E M; Jirsa, Franz; Fellner-Frank, Christine
In Lake Naivasha, the common carp Cyprinus carpio L. 1758 was accidentally introduced from fish farms adjacent to River Malewa in 1999 and now forms the bulk of the total fish caught. Since its introduction, no study has been made on its parasitic community nor are there any reports on ectoparasites from other fish species in this lake to the best of our knowledge. Therefore, the aim of this study was to describe the parasitic community of C. carpio and two other commercially important fish species: Oreochromis leucostictus and Tilapia zillii. Additionally, the abundant Barbus paludinosus was included in the study. A total of 286 fish (145C. carpio, 56 O. leucostictus, 18 T. zillii, and 67 B. paludinosus) were collected during the year 2011 and examined. Ten taxa of parasites were recovered from C. carpio dominated by the monogenean Dactylogyrus minutus, occurring with a prevalence (p) of 99.3 %. Thirteen taxa of parasites were identified from O. leucostictus dominated by monogeneans Cichlidogyrus spp. (p = 91.1 %). T. zillii harbored nine taxa of parasites with the digenean Tylodelphys sp. (p = 83.3 %) being dominant and B. paludinosus harbored 11 taxa of parasites dominated by an unidentified monogenean of the genus Dactylogyrus (p = 83.6 %). C. carpio had the lowest helminth species diversity and richness while monogenetic trematodes, which have never been reported from fish in Lake Naivasha, were the most prevalent parasites recovered.
Enhanced Utilization of Biotechnology Research and Development Innovations in Eastern and Central Africa for Agro-ecological Intensification
(Springer, 2014-07-16) Masiga, Clet Wandui; Mugoya, Charles; Ali, Rasha; et al
The Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA) through its Agrobiodiversity and Biotechnology Programme is enhancing the utilization of biotechnology research and development innovations in Eastern and Central Africa (ECA). We present successes in the application of biotechnology to enhance the productivity of cassava, sweet potato, banana, maize and sorghum in ECA. These products—drought tolerant maize, sorghum resistant to striga, as well as the technology for producing and distributing disease free planting materials of cassava, sweet potato and banana to farmers—are central for the agro-ecological intensification of farming systems in the central African highlands.
Occurrence and abundance of plant parasitic nematodes in cabbage-based cropping systems in Kenya.
(2014-10) Mwangi, J. M.1; Waceke, J. W. 2; Kariuki, G. M. 2
A survey was conducted to determine the incidences of plant parasitic nematodes (PPN) and factors enhancing population build-up in cabbage (Brassica oleracea L. var capitata)-based cropping system in selected agro-ecological zones of Kenya. Samples were collected from sixty cabbage growing farms in Nyandarua and Embu Counties. Nematodes assay was conducted for both root and soil samples. Extraction of PPN from soil and root sample was done using modified extraction tray method and modified maceration extraction technique respectively. Extracted nematodes were enumerated, identified to genus level and their frequencies of occurrence and abundance determined. Nematodes belonging to various genera were found associated with cabbage in six agro-ecological zones. The study revealed that cabbage is a preferable host to lesion nematodes (Pratylenchus) with 87% and 58% frequency of occurrence in soil and roots, respectively. The mean population of this nematode in soil and root samples was significantly different from other nematode general. Meloidogyne spp. were present at low frequency of 42% and 23% in soil and roots and density 6.36/100 cm3 of soil and 1.1/10 g roots. Helicotylenchus spp. were recovered in significant numbers with 82% frequency of occurrence in rhizosphere and 27% in roots and a density of 26.28/100 cm3 in soils and less than 1 nematode per 10 g of roots. Tylenchorhynchus spp. occurred in 67% of the soil samples while Paratrichodorus, Trichodorus and Paratylenchus spp. were present in 78%, 57% and 58% frequency of occurrence in the cabbage rhizosphere but at a low population density. Other PPN detected in low frequencies of occurrence and density include; Tylenchus, Scutellonema, Xiphinema spp. among others. The study encourages more research work to establish the economic importance and the management of the reported nematode pests.
An Inventory and Assessment of Exotic and Native Plant Species Diversity in the Kenyan Rangelands:-Case Study of Narok North Sub-County.
(2015) Cheche, Winnie W.; Githae, Eunice W.; Magana, Adiel E. M.
A botanical inventory and diversity of exotic and native species was assessed in the rangeland of Narok North sub-County, Kenya. A total of 72 species were recorded, composed of 64 species of trees and shrubs and eight species of herbs. They belonged to 34 families and 52 genera. Fabaceae was the richest family with 16 species, followed by Euphorbiaceae (five), Moraceae and Myrtaceae (four each). In total, 48 species were native and 24 exotics with a diversity index H of 1.082 and 0.604, respectively. Hypericum revolutum, a native shrub, was the most dominant with an importance value of 3.81, followed by three exotic species; Datura suaveolens (an invasive species), Dovyalis caffra and Hibiscus rosa-sinesis with importance values of 3.40, 3.35 and 3.23, respectively. The native species were abundant in undisturbed areas while the exotics were most common in areas with vegetation cover less than 60%. Four invasive alien species were encountered namely; D. suaveolens, Lantana camara, L. trifolia and Opuntia ficus-indica. They all had a high density that indicated greater establishment success. This inventory affirms that the rangelands of Narok North are undergoing serious changes in vegetation structure and composition due to human activities and requires urgent attention to conserve biodiversity and genetic resources.
Behavioral patterns and responses to human disturbance of wild somali ostrich in Samburu, Kenya
(2016) Mutiga, MaricianoIguna 1; Muoria, Paul Kimata 2; Kotut, Kiplagat 1; Karuri, Hannah Wangari 1
Somali ostrich has suffered a drastic decline in its population and range mainly due to hunting over the years for meat, skin and feathers. Urgent conservation measures should therefore be taken to reverse this trend particularly in their current population stronghold, the Samburu landscape. In this range, the magnitude and consequences of human disturbance on the ostrich has not been established. The aim of this study was therefore to investigate the behavioural patterns and assess the impacts of human disturbance to the bird. Focal animal sampling was used to establish ostrich‟s behavioural activity budget while the magnitude of human disturbance was assessed by determining and comparing flight initiation distances in the protected and partially protected areas. Somali ostrich spent most of their diurnal time in feeding and moving, and are more sensitive to human disturbance in the protected areas than they are in the partially protected areas. The results of this study imply that the ratite does not differ in behavioural patterns from other extant ostrich species and human disturbance is not posing a significant threat to its survival within Samburu landscape. Further studies are recommended for better understanding of the conservation status of the newly published species.
Molecular characterization of wood ear mushrooms [Auricularia sp.] from Kakamega Forest in Western Kenya
(Current Research in Environmental & Applied Mycology, 2016-03-30) B.O., Onyango; C. M., Mbaluto; C. S., Mutuku; D. O., Otieno
Mushrooms of the genus Auricularia, generally termed wood ear mushrooms are in high demand in Western Kenya due to their numerous medicinal and nutritional properties. Interventions to characterize and conserve the native wood ear mushrooms are necessary to mitigate possible extinction of this valuable bio-resource. Currently, the species richness and bio-geographical relatedness of the Kenyan native wood ears is not fully elucidated. This study used molecular sequence analysis of the internal transcribed spacer (ITS) and the 28S nuclear ribosomal large subunit (nLSU) genes in species delimitation of six strains of wood ear mushrooms native to Kakamega Forest. Phylogeny of both the ITS and nLSU gene regions showed that three strains clustered with Auricularia delicata while the other three strains clustered with Auricularia polytricha at bootstrap support values of above 97%. An intragenomic dichotomy appeared to occur in the Auricularia delicata strains based on the genetic distance of the nLSU gene sequences. The wood ear mushrooms identified from the Kakamega Forest strains were Auricularia delicata and Auricularia polytricha and not Auricularia auricula as previously reported. This rich biodiversity needs further exploration to widen the nutritional and medicinal base of the rural populace who depend on the mushrooms through conservation, cultivation and commercialization activities.
Agrobiodiversity conservation enhances food security in subsistence-based farming systems of Eastern Kenya
(2016-09-15) Mburu, Simon Wambui; Koskey, Gilbert; Kimiti, Jacinta Malia; Ombori, Omwoyo; Maingi, John M.; Njeru, Ezekiel Mugendi
Background Globally, there is great concern about expanding agricultural activities due to their impact in the conservation of agrobiodiversity. African continent is known for its richness in biodiversity. In Kenya, there is a continuous unabated expansion of agriculture into natural habitats due to demographic and economic pressures posing a significant threat to biodiversity. Therefore, there is a need to study biodiversity loss and its regain through practices in agricultural landscapes. In this study, we assessed the status of agrobiodiversity and its contribution to food security in four agroecological zones of Eastern Kenya. Sixty households were sampled from two selected agroecological zones (upper and lower midland zones) in Embu and Tharaka-Nithi counties. Structured questionnaires and checklists were used to collect the data. Results Thirty-nine crop species were identified dominated by vegetables, fruits, legumes and cereals with relative densities of 28.8, 20.5, 18.3 and 8.3 %, respectively. Embu Lower Midland and Tharaka-Nithi Lower Midland zones had relatively higher crop species richness of 243 and 240, respectively, and Shannon–Wiener diversity indices (H′) of 3.403 and 3.377, respectively, compared with Embu Upper Midland and Tharaka-Nithi Upper Midland zones with species richness of 229 and 207, respectively, and H′ of 3.298 and 3.204, respectively. Conclusions Households from lower midland zones with high crop diversity and richness were more food secure compared with those from the Upper Midland zones with low crop diversity and richness. These findings suggest that farm production systems with high agrobiodiversity contributed more toward food security among smallholder farmers in the selected sites.
Novel Sources of Witchweed (Striga) Resistance from Wild Sorghum Accessions
(2017-02) Mbuvi, Dorothy 1; Masiga, Clet W. 2,3; Kuria, Eric 1; Masanga, Joel 1; Wamalwa, Mark 1; Mohamed, Abdallah 4; Odeny, Damaris 5; Hamza, Nada 3,6; Timko, Michael P. 7*; Runo, Stephene 1*
Sorghum is a major food staple in sub-Saharan Africa (SSA), but its production is constrained by the parasitic plant Striga that attaches to the roots of many cereals crops and causes severe stunting and loss of yield. Away from cultivated farmland, wild sorghum accessions grow as weedy plants and have shown remarkable immunity to Striga. We sought to determine the extent of the resistance to Striga in wild sorghum plants. Our screening strategy involved controlled laboratory assays of rhizotrons, where we artificially infected sorghum with Striga, as well as field experiments at three sites, where we grew sorghum with a natural Striga infestation. We tested the resistance response of seven accessions of wild sorghum of the aethiopicum, drummondii, and arundinaceum races against N13, which is a cultivated Striga resistant landrace. The susceptible control was farmer-preferred variety, Ochuti. From the laboratory experiments, we found three wild sorghum accessions (WSA-1, WSE-1, and WSA-2) that had significantly higher resistance than N13. These accessions had the lowest Striga biomass and the fewest and smallest Striga attached to them. Further microscopic and histological analysis of attached Striga haustorium showed that wild sorghum accessions hindered the ingression of Striga haustorium into the host endodermis. In one of the resistant accessions (WSE-1), host and parasite interaction led to the accumulation of large amounts of secondary metabolites that formed a dark coloration at the interphase. Field experiments confirmed the laboratory screening experiments in that these same accessions were found to have resistance against Striga. In the field, wild sorghum had low Area under the Striga Number Progressive curve (AUSNPC), which measures emergence of Striga from a host over time. We concluded that wild sorghum accessions are an important reservoir for Striga resistance that could be used to expand the genetic basis of cultivated sorghum for resistance to the parasite.
Potential of native rhizobia in enhancing nitrogen fixation and yields of climbing beans (Phaseolus vulgaris L.) in Contrasting Environments of Eastern Kenya
(2017-03-13) Koskey, Gilbert 1,; Mburu, Simon W. 1; Njeru, Ezekiel M. 1*,; Kimiti, Jacinta M. 2; Ombori, Omwoyo 3; Maingi, John M. 1
Climbing bean (Phaseolus vulgaris L.) production in Kenya is greatly undermined by low soil fertility, especially in agriculturally prolific areas. The use of effective native rhizobia inoculants to promote nitrogen fixation could be beneficial in climbing bean production. In this study, we carried out greenhouse and field experiments to evaluate symbiotic efficiency, compare the effect of native rhizobia and commercial inoculant on nodulation, growth and yield parameters of mid-altitude climbing bean (MAC 13 and MAC 64) varieties. The greenhouse experiment included nine native rhizobia isolates, a consortium of native isolates, commercial inoculant Biofix, a mixture of native isolates + Biofix, nitrogen treated control and a non-inoculated control. In the field experiments, the treatments included the best effective native rhizobia isolate ELM3, a consortium of native isolates, a commercial inoculant Biofix, a mixture of native isolates + Biofix, and a non-inoculated control. Remarkably, four native rhizobia isolates ELM3, ELM4, ELM5, and ELM8 showed higher symbiotic efficiencies compared to the Biofix. Interestingly, there was no significant difference in symbiotic efficiency between the two climbing bean varieties. Field results demonstrated a significant improvement in nodule dry weight and seed yields of MAC 13 and MAC 64 climbing bean varieties upon rhizobia inoculation when compared to the non-inoculated controls. Inoculation with ELM3 isolate resulted to the highest seed yield of 4,397.75 kg ha−1, indicating 89% increase over non-inoculated control (2,334.81 kg ha−1) and 30% increase over Biofix (3,698.79 kg ha−1). Farm site significantly influenced nodule dry weight and seed yields. This study, therefore, revealed the potential of native rhizobia isolates to enhance delivery of agroecosystem services including nitrogen fixation and bean production. Further characterization and mapping of the native isolates will be imperative in development of effective and affordable commercial inoculants.
Modifying Surber sampling technique increases capture of freshwater crabs in African upland streams. Inland Waters. 2:11-15
(2017-04-03) Magana, Adiel; Dobson, Michael; Mathooko, Jude M.
We compared 2 methods for sampling the freshwater crab Potamonautes odhneri (Colosi) in Kenyan streams: standard Surber sampling, in which a sample is taken over a period of several minutes; and rapid Surber sampling, in which the process is reduced to around 10 seconds. Rapid Surber sampling caught more crabs than standard Surber sampling, This suggests that the crab species investigated is normally able to evade capture if sampling is carried out at an unhurried pace, but that if precision is sacrificed for speed, then capture efficiency increases. The size of crabs caught using the 2 techniques was similar, and use of baited traps set in the same locations showed that Surber sampling methods were not capturing larger individuals. Like all methods available to sample large benthic crustaceans, rapid Surber sampling has its limitations, but this study demonstrates that it can be used as a method for rapid assessment of crab presence and for comparative determination of population density, to significantly greater effect than the standard method of Surber sampling.
Habits of a highly successful cereal killer, Striga
(PLOS Pathogens, 2018-01-11) Runo, Steven; Kuria, Erick K.
Striga is a highly successful pathogen of cereal crops in sub-Saharan Africa. Also known as witchweed, Striga is an attractive parasitic plant whose beautiful flowers belie its noxiousness. Most cultivated cereals, including maize, millet, sorghum, and rice, are parasitized by at least one Striga species, leading to enormous economic losses. Control strategies are limited but include common agronomic practices of hand weeding, crop rotation, and general sanitization techniques. Striga-resistant crops, as well as tolerant ones, have also been used, but this resistance tends to break down with the emergence of new Striga variants. With limited and ineffective management options, Striga has continued to increase both its host range and area under infestation. In this article, we outline seven unique characteristics of Striga as a parasite of great economic importance, explore reasons for its success, and outline emerging control options.
Status of Opuntia invasions in the arid and semi-arid lands of Kenya
(CAB Reviews, 2018-03) Githae, Eunice W. *
Invasive alien species (IAS) are among the leading threats to biodiversity, food security and human well-being. Opuntia (prickly pear cactus) is one of the most widespread and naturalized in the arid and semi-arid areas of Kenya, with extreme effects on rural livelihoods and the environment. However, comprehensive information on the status of invasion in the country is lacking, which is crucial for developing strategies for prevention and management. This paper, therefore, provides an overview of the interacting factors that influence its invasion in Kenya in terms of species diversity, pathways of introduction, negative impacts and the effectiveness of regulations and control measures. Seven invasive species of Opuntia are present in the country with the most abundant (O. stricta) being under biocontrol trial. These species have the same habitat preferences, physiological traits, negative impacts, introduction pathways and management options. Invasion is mainly attributed to changes in land use and consequent land degradation. Introduction pathways are largely intentional for ornamental purposes but unintentional at a local scale through escape from gardens and natural dispersal. The most applied methods of managing Opuntia are mechanical and chemical methods that are unsustainable and labour-intensive at large scale. Effective policies are therefore needed to prevent an increase in the significant negative impacts caused by IAS including those that have a limited distribution.
Genetic Characterization and Diversity of Rhizobium Isolated from Root Nodules of Mid-Altitude Climbing Bean (Phaseolus vulgaris L.) Varieties.
(2018-05-15) Koskey, Gilbert 1,; Mburu, Simon W. 1; Kimiti, Jacinta M. 2; Ombori, Omwoyo 3,; Maingi, John M. 1*; Njeru, Ezekiel M. 1
The increasing interest in the use of rhizobia as biofertilizers in smallholder agricultural farming systems of the Sub-Saharan Africa has prompted the identification of a large number of tropical rhizobia strains and led to studies on their diversity. Inoculants containing diverse strains of rhizobia have been developed for use as biofertilizers to promote soil fertility and symbiotic nitrogen fixation in legumes. In spite of this success, there is paucity of data on rhizobia diversity and genetic variation associated with the newly released and improved mid-altitude climbing (MAC) bean lines (Phaseolus vulgaris L.). In this study, 41 rhizobia isolates were obtained from the root nodules of MAC 13 and MAC 64 climbing beans grown in upper and lower midland agro-ecological zones of Eastern Kenya. Eastern Kenya was chosen because of its high production potential of diverse common bean cultivars. The rhizobia isolates were characterized phenotypically on the basis of colony morphology, growth and biochemical features. Rhizobia diversity from the different regions of Eastern Kenya was determined based on the amplified ribosomal DNA restriction analysis (ARDRA) of PCR amplified 16S rRNA genes using Msp I, EcoR I, and Hae III restriction enzymes. Notably, native rhizobia isolates were morphologically diverse and grouped into nine different morphotypes. Correspondingly, the analysis of molecular variance based on restriction digestion of 16S rRNA genes showed that the largest proportion of significant (p < 0.05) genetic variation was distributed within the rhizobia population (97.5%) than among rhizobia populations (1.5%) in the four agro-ecological zones. The high degree of morphological and genotypic diversity of rhizobia within Eastern Kenya shows that the region harbors novel rhizobia strains worth exploiting to obtain strains efficient in biological nitrogen fixation with P. vulgaris L. Genetic sequence analysis of the isolates and testing for their symbiotic properties should be carried out to ascertain their identity and functionality in diverse environments.
Reproduction of Globodera pallida on tissue culture-derived potato plants and their potential use in resistance screening process.
(2019-06-17) Mwangi, James M. 1,2; Niere, Björn 1; Daub, Matthias 1; Finckh, Maria R. 2; Kiewnick, Sebastian 1
Globodera pallida infestation on potato is responsible for huge yield losses globally. Screening of potato germplasm for resistance to the nematode at the early stages of a breeding programme can significantly enhance resistance-based management. This study assessed the suitability of tissue culture (TC)-derived potato plants as screening material for resistance to G. pallida. Reproduction of the nematode on TC plants was similar to the reproduction on tuber- and eye-plug-derived plants. The pot volume, inoculum density and inoculation time had a significant effect on the reproduction. A positive correlation was found between the mean number of white females on the root surface and the final number of nematode cysts after extraction. Resistance ranking using TC plants and the tubers yielded comparable results, thus justifying the use of TC in the screening process. Tissue culture plants have the potential of speeding up the screening process and reducing resource requirements, thus lowering breeding cost.
Characteristics of Waste Pickers in Nakuru and Thika Municipal Dumpsites in Kenya
(Journal of Applied Science and Technology, 2019-08-21) Kariuki, Joseph Maina; Bates, Margaret; Magana, Adiel
Dumpsite waste picking is prevalent in many developing countries of which Kenya is one. Waste pickers play an important role in waste recycling by recovering and providing materials to the waste recycling industry. Aim: The purpose of the study was to characterise the demographic and socio-economic factors of waste pickers in Nakuru and Thika municipal dumpsites. Study Design: The research design was a cross-sectional social survey and the sample size was 167. Place and Duration of Study: The study was carried out in the largest dumpsite in Nakuru and Thika towns found in Nakuru and Kiambu counties respectively. Methodology: The data was collected by use of structured questionnaire. The data was analysed using the Statistical Package for Social Sciences. Analysis was by frequency tables, χ2 test and ttest at 95% level of confidence. Results: The results show that there was parity by gender in Nakuru but in Thika the proportion of females was much higher than that of males. There was significant association between age and site of operation with waste pickers in Thika being on average younger than in Nakuru (χ = 12.605, d.f. = 3, p = 0.006). Waste pickers in Thika had on average attained a higher level of education than in Nakuru (χ2 = 12.352, d.f. = 3, p = 0.006). Most of the waste pickers (96%) only picked from exclusively from the dumpsite. Waste pickers in Thika spent an average of 10.26±0.23 hours daily in waste picking which was significantly higher (t=-3.709, n=160, p<.001) than at Nakuru (8.97±0.27 hours). The mean number of years of waste picking in Thika was significantly less than in Nakuru (t=4.627, d.f.=158, p<.001). Conclusion: In conclusion, waste pickers play an important role in waste recycling, with waste picking supporting hundreds of waste pickers in the study area, who are important in integrated waste management and need to be understood, appreciated and supported.
Effector gene vap1based DGGE fingerprinting to assess variation within and among Globodera species and populations.
(2019-11-12) Nuaima, Rasha Haj 1 , 2; Mwangi, James M. 3; Kiewnick, Sebastian 3; Heuer, Holger 1
Population-level genetic tools to study the epidemiology of potato cyst nematodes (PCN) are needed to evaluate their adaptive potential and validate management strategies. The effector gene vap1 is essential in early infection by PCN. We expected high allelic variation due to diversifying selection. A technique was developed specifically to amplify vap1 fragments of PCN, and electrophoretically separate variants in a denaturing gradient (DGGE). Sequenced gene variants differed in intron as well as exon regions. Siblings were more similar in vap1 pattern than juveniles from different cysts. Nearly all juveniles analysed had unique patterns with up to ten or five vap1 variants for Globodera pallida or G. rostochiensis, respectively. Patterns differed significantly among populations, with similarities increasing from between-species, within-species to within-pathotype comparisons. In conclusion, the method is suitable to determine the similarity of heterogeneous PCN populations for studies on their temporal change and spread.

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