BC-Department of Plant and Microbial Sciences

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    Coffee
    (Taylor & Francis, 2005) Gathaara, M. P. H.; Njoroge, J. M.; Agwanda, C. O.; Kingori, P. N.; Karanja, A. M.
    Information on the agronomy, trade, and future outlook of coffee is presented. Other subjects include: (1) historical background; (2) genetic resources; (3) breeding and selection; (4) breeding programmes; (5) field management; (6) diseases; (7) pests; (8) effects of consumer needs on adaptation; and (9) research and development organizations. The genus Coffea consists of more than 80 species. Coffea arabica is a native of Central Africa (Congo and Zaire). Coffea canephora (Robusta coffee) was introduced to India from Indonesia and Sri Lanka in the late 19th century when C. arabica started showing severe incidence of leaf rust. Coffea congensis, which has a compact bush habit and seeds of better quality, was introduced in India in the 1930s. At present, the Central Coffee Research Institute in Karnataka, India, has a collection of 18 species that belong to Coffea and the closely related genus Psilanthus. With an annual turnover of US$ 10 billion, coffee is the second most traded commodity after petroleum. Currently, world prices are under pressure by large quantities of poor quality coffees from countries such as Vietnam.
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    The Coffee Exporter's Guide - Third Edition
    (International Trade Centre, 2011) Gathaara, M. P. H.
    Guide providing information on trade practices relating to exporting coffee – presents an overview of the world coffee trade and markets; deals with international coffee contracts (Europe and United States), logistics, insurance, dispute resolution, futures markets, risk management and hedging, trade financing, and related management issues; covers coffee quality with a special emphasis on quality control aspects; outlines new trends in the coffee trade such as electronic commerce, niche markets, organic certification, fair trade labelling, and other sustainability schemes; highlights climate change and environmental issues relevant to the coffee industry; includes a list of frequently asked questions from coffee producers and the respective answers.
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    Enhancement of coffee quality in Kenya by prevention of mould current status and future outlook.
    (Association Scientifique Internationale du Café, 2001-05) Gathaara, M. P. H.
    A survey was conducted to find out the likely risk areas in the production chain namely, the primary and secondary processing facilities and in green coffee warehouses of the marketing body. Results indicated that there were conditions such as leaking roofs, crevices in the tools, and long storage periods that could favour growth of moulds. The recommended processing procedures, the survey, and the activities proposed as Kenya's contribution to the global project on coffee quality improvement thorough prevention of mould growth are described.
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    Ethnobotanical survey and efficacy of antituberculosis medicinal plants around the Lake Victoria region of Kenya.
    (IUCEA, 2012) Okemo, P. O.; Mariita, Richard M.; Orodho, John Aluko
    In Africa, more than 70% of the people use ethnomedicine for their healthcare. With the emergence of new diseases and drug resistance to infections, traditional medicine should be given more attention in modern research and development. The aim of the study was to carry out an Ethnobotanical survey on the antimycobacterial plants used by the communities living around the Lake Victoria Basin of Kenya, and to screen their crude extracts against various mycobacteria strains. From the survey, 17 medicinal plants were collected. They were identified at the Department of Pharmacy and Complimentary Alternative Medicine, Kenyatta University, Nairobi, Kenya, in whose herbarium voucher specimens were deposited. Methanolic extracts from the plants were tested against four strains of Mycobacteria (Mycobacteria tuberculosis, M. kansasii, M. fortuitum, and M. smegmatis), which were obtained from Kenya Medical Research Institute (KEMRI), Nairobi, Kenya. A BACTEC MGIT 960 system was used to bioassay the extracts. All the plant extracts inhibited mycobacterial growth at 2.0 mg/mL. Aloe secundiflora gave strong antimycobacterial activity (zero GUs) against M. kansasii, at all concentrations used. Entada abysinnica was active (zero GUs at all concentrations used) against M. tuberculosis. Carissa edulis and Vernonia amygdalina were the most potent against M. smegmatis and M. fortuitum, completely inhibiting their growth (Zero GUs) at all concentrations used. Similarly, Toddalia asiatica had high inhibitory activity (Zero GUs) against M. tuberculosis and M. kansasii at all concentrations used. The results provide an indication that some of the tested plants may contain compounds that could be used against tuberculosis.
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    Exploiting Arbuscular Mycorrhizal Fungi-Rhizobia-Legume Symbiosis to Increase Smallholder Farmers’ Crop Production and Resilience Under a Changing Climate
    (Springer, 2020) Njeru, Ezekiel Mugendi; Muthini, Morris; Muindi, Mercy Martha; Ombori, Omwoyo; Nchore, Shem Bonuke; Runo, Steve; Maingi, John M.
    Beneficial soil microbiota, such as arbuscular mycorrhizal fungi (AMF) and rhizobia, provide essential agroecosystem services in smallholder farming systems. Such microorganisms have great potential to promote crop production and resilience under a changing climate in sub-Saharan Africa. However, their function is affected by agronomic management practices, crop genotype and soil quality, among other factors. In this work, we sought to determine the effect of soil quality and crop genotype on nodulation, percentage mycorrhizal colonization and growth of maize and cowpea crops. Soil samples were obtained from ten smallholder farms with known management history in Embu and Kitui counties of Kenya and analysed for physicochemical parameters. Greenhouse bioassays were then carried out, where the samples were put in sterilized pots in four replicates and maintained in a completely randomized design. Four cowpea and maize genotypes (locally grown landraces and recommended genotypes from Kenya Agricultural and Livestock Research Organization) were grown in pots for 40 days. After harvesting, nodulation in the case of cowpea, shoot dry weights and mycorrhizal root colonization were determined. Remarkably, cowpea genotypes differed significantly (p < 0.0001) in nodule number. The locally cultivated landrace (C2) recorded the lowest nodulation with 30.4 nodules plant−1, compared to the open pollinated varieties (OPVs): C1, 39.15; C3, 43.70; and C4, 40.6 nodules plant−1. Among the maize genotypes, the locally cultivated landrace (M3) recorded a significantly (p = 0.008) higher percentage of mycorrhizal root colonization (68.9%) compared to the OPVs: M1 58.1% and M2 65.3%, while the hybrid (M4) had the lowest root colonization of 57.8%. Soil characteristics influenced nodulation and mycorrhizal colonization, where soil P was positively correlated to cowpea nodulation. Soil organic matter, nitrogen, pH and calcium positively correlated with AMF maize root colonization. Our results demonstrate the strong effect of soil quality and crop genotype on AMF-rhizobia-legume symbiosis, which affects overall crop growth and production. These factors should therefore be critically considered during the development of efficient low-cost inocula for enhanced smallholder farmers’ crop production.
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    Phylogenetic analysis of the envelope HIV-1 type 1 isolates among Kenyan cohort
    (American Society for Microbiology, 1999-05) Nyamache, A. K.; Muigai, A.W.T.; Khamadi, Samoel A.
    In sub-Saharan Africa, where the effects of human immunodeficiency virus type 1 (HIV-1) have been most devastating, there are multiple subtypes of this virus. The distribution of different subtypes within African populations is generally not linked to particular risk behaviors. Thus, Africa is an ideal setting in which to examine the diversity and mixing of viruses from different subtypes on a population basis. In this setting, it is also possible to address whether infection with a particular subtype is associated with differences in disease stage. To address these questions, we analyzed the HIV-1 subtype, plasma viral loads, and CD4 lymphocyte levels in 320 women from Nairobi, Kenya. Subtype was determined by a combination of heteroduplex mobility assays and sequence analyses of envelope genes, using geographically diverse subtype reference sequences as well as envelope sequences of known subtype from Kenya. The distribution of subtypes in this population was as follows: subtype A, 225 (70.3%); subtype D, 65 (20.5%); subtype C, 22 (6.9%); and subtype G, 1 (0.3%). Intersubtype recombinant envelope genes were detected in 2.2% of the sequences analyzed. Given that the sequences analyzed represented only a small fraction of the proviral genome, this suggests that intersubtype recombinant viral genomes may be very common in Kenya and in other parts of Africa where there are multiple subtypes. The plasma viral RNA levels were highest in women infected with subtype C virus, and women infected with subtype C virus had significantly lower CD4 lymphocyte levels than women infected with the other subtypes. Together, these data suggest that women in Kenya who are infected with subtype C viruses are at more advanced stages of immunosuppression than women infected with subtype A or D. There are at least two models to explain the data from this cross-sectional study; one is that infection with subtype C is associated with a more rapid disease progression, and the second is that subtype C represents an older epidemic in Kenya. Discriminating between these possibilities in a longitudinal study will be important for increasing our understanding of the role of specific subtypes in the transmission and pathogenesis of HIV-1.