Pigmented leukocytes are reported to be associated with severe malaria (SM). Blood smears from a case-control study of SM conducted in Apac Hospital in Northern Uganda were examined for pigmented leukocytes to investigate their association with measures of disease and clinical immunity in children less than 5 years old. Pigmented leukocytes, predominated by monocytes, were significantly greater in number in SM by comparison with uncomplicated malaria (UM). SM children with no pigmented leukocytes had significantly elevated hemoglobin, packed cell volumes, and titers of IgG anti-SERA5 by comparison with SM children with pigmented leukocytes. These differences were not observed in UM. A Spearman rank correlation analysis showed, in addition, a negative but weak correlation between pigmented monocytes and titers of IgG anti-Plasmodium falciparum lysate and IgG anti-EBA-175 in both SM and UM children. Thus, numbers of pigmented monocytes might be negative correlates of clinical immunity in a region of holoendemic malaria.

Fusarium oxysporum f. sp. cubense (Foc) is one of the major threats to dessert banana (Musa spp.) production. In Uganda, 'Sukali Ndiizi' is one of the most popular dessert banana cultivars and it is highly susceptible to Fusarium wilt. Development of resistant cultivars through transgenic approaches has shown to offer one of the most effective control options for most diseases. The transgenic approaches for providing plant disease resistance have mainly been through either enzymatic destruction of pathogen structures, neutralization of pathogen and its products or production of metabolites that eventually kill the pathogen. However in recent years, methods that prevent cell death of host plant after infection especially for necrotrophic pathogens like F. oxysporum have registered success in providing resistance in several crops. We investigated whether the transgenic expression of a programmed cell death inhibition gene in Sukali Ndiizi could be used to confer Fusarium resistance to Foc race 1. Embryogenic cell suspensions of cv. 'Sukali Ndiizi, were stably transformed with a synthetic, plant-codon optimise mCed-9 gene. Twenty-eight independently transformed plant lines were regenerated. The lines were inoculated with Foc race 1 and observed for 13 weeks in small-plant glasshouse. Three transgenic lines showed significantly lower internal and external disease symptoms than the wild-type susceptible 'Sukali Ndiizi' banana plants used as controls. This is the first report from Africa on the generation of Fusarium wilt tolerant transgenic 'Sukali Ndiizi', a very popular but rapidly diminishing African dessert banana.

Coffea canephora has high but inadequately exploited genetic diversity. This diversity, if well exploited, can sustain coffee productivity amidst climate change effects. Drought and heat stress are major global threats to coffee productivity, quality, and tradable volumes. It is not well understood if there is a selectable variation for drought stress tolerance in Robusta coffee half-sibs as a result of watering deficit pre-exposure at the germination stage. Half-sib seeds from selected commercial clones (KR5, KR6, KR7) and a pipeline clone X1 were primed with deficit watering at two growth stages followed by recovery and later evaluated for tolerance to watering deficit stress in three different temperature environments by estimation of plant growth and wilt parameters. Overall, the KR7 family performed the best in terms of the number of individuals excelling for tolerance to deficit watering. In order of decreasing tolerance, the 10 most promising individuals for drought and heat tolerance were identified as: 14.KR7.2, 25.X1.1, 35.KR5.5, 36.KR5.6, 41.KR7.5, 46.KR6.4, 47.KR6.5, 291.X1.3, 318.X1.3, and 15.KR7.3. This is the first prospect into the potential of C. canephora half-sibs’ diversity as an unbound source of genetic variation for abiotic stress tolerance breeding.

Gene transfer into the plant cell is a key step towards its successful genetic modification and its efficiency is heavily dependent on plant and bacterial cell biological status and a wide array of physical conditions. Gene transfer efficiencies in East African Highland Banana (EAHB) cell lines remains low compared to other monocotyledonous crops like rice and wheat due to factors such as high oxidative stress. The use of antioxidants is fundamental in influencing gene transfer events during Agrobacterium-plant cell co-cultivation. Here we report significant enhancement of gene transfer efficiency in the EAHB cultivar 'Nakinyika' (EA-AAA) by supplementing co-cultivation medium with antioxidants; ascorbic acid (AA), glutathione (GSH), tocopherol (TOC) and silver nitrate (SN). The most enhancing antioxidant by number of blue foci after histochemical assay, as a parameter of gene transfer efficiency, was ascorbic acid (174 cells) at a concentration of 40 mg/L, followed by glutathione (91 cells) and tocopherol (91 cells) both at 50 mg/L. The least enhancement was observed when ascorbic acid (39 cells), silver nitrate (41 and 31 cells) were used at concentrations of 20, 4 and 6 mg/L compared to 72 cells in controls (no anti-oxidants). Regeneration efficiency increased from 29 cells in controls to 46% for SN at 8 mg/L; 43% for GSH at 100 mg/L; 30% for TOC at 75 mg/L; and 48% for AA at 20 mg/L. Polymerase chain reaction (PCR) results using gusA specific primers showed that these regenerants were putative transformants and grew normally during regeneration, rooting and multiplication. GSH and TOC significantly enhanced gene transfer efficiency while AA and SN showed significant increases in shoot regeneration compared to controls. The current results show that antioxidants significantly enhance gene transfer and regeneration efficiency in recalcitrant banana cell lines and could significantly enhance the overall transformation efficiencies in cases where numerous transgenic lines are required in a short time.