Validation of KASP markers associated with cassava mosaic disease resistance, storage root dry matter and provitamin A carotenoid contents in Ugandan cassava germplasm

Open Access Journal; Published online: 23 Nov 2022Introduction The intrinsic high heterozygosity of cassava makes conventional breeding ineffective for rapid genetic improvement. However, recent advances in next-generation sequencing technologies have enabled the use of high-density markers for genome-wide association studies, aimed at identifying single nucleotide polymorphisms (SNPs) linked to major traits such as cassava mosaic disease (CMD) resistance, dry matter content (DMC) and total carotenoids content (TCC). A number of these trait-linked SNPs have been converted to Kompetitive allele-specific polymerase chain reaction (KASP) markers for downstream application of marker assisted selection. Methods We assayed 13 KASP markers to evaluate their effectiveness in selecting for CMD, DMC and TCC in 1,677 diverse cassava genotypes representing two independent breeding populations in Uganda. Results Five KASP markers had significant co-segregation with phenotypes; CMD resistance (2), DMC (1) and TCC (2), with each marker accounting for at least 30% of the phenotypic variation. Markers located within the chromosomal regions for which strong marker-trait association loci have been characterised (chromosome 12 markers for CMD, chromosome 1 markers for DMC and TCC) had consistently superior ability to discriminate the respective phenotypes. Discussion The results indicate varying discriminatory abilities of the KASP markers assayed and the need for their context-based use for MAS, with PSY2_572 particularly effective in selecting for high TCC. Availing the effective KASP markers on cost-effective genotyping platforms could facilitate practical implementation of marker-assisted cassava breeding for accelerated genetic gains for CMD, DMC and provitamin A carotenoids

Population pharmacokinetics of antimalarial naphthoquine in combination with artemisinin in Tanzanian children and adults: dose optimization

The combination antimalarial therapy of artemisinin-naphthoquine (ART-NQ) was developed as a single-dose therapy, aiming to improve adherence relative to the multiday schedules of other artemisinin combination therapies. The pharmacokinetics of ART-NQ has not been well characterized, especially in children. A pharmacokinetic study was conducted in adults and children over 5 years of age (6 to 10, 11 to 17, and >/=18 years of age) with uncomplicated malaria in Tanzania. The median weights for the three age groups were 20, 37.5, and 55 kg, respectively. Twenty-nine patients received single doses of 20 mg/kg of body weight for artemisinin and 8 mg/kg for naphthoquine, and plasma drug concentrations were assessed at 13 time points over 42 days from treatment. We used nonlinear mixed-effects modeling to interpret the data, and allometric scaling was employed to adjust for the effect of body size. The pharmacokinetics of artemisinin was best described by one-compartment model and that of naphthoquine by a two-compartment disposition model. Clearance values for a typical patient (55-kg body weight and 44.3-kg fat-free mass) were estimated as 66.7 L/h (95% confidence interval [CI], 57.3 to 78.5 L/h) for artemisinin and 44.2 L/h (95% CI, 37.9 to 50.6 L/h) for naphthoquine. Nevertheless, we show via simulation that patients weighing >/=70 kg achieve on average a 30% lower day 7 concentration compared to a 48-kg reference patient at the doses tested, suggesting dose increases may be warranted to ensure adequate exposure. (This study has been registered at ClinicalTrials.gov under identifier NCT01930331.)

Interaction patterns determining improved information and knowledge sharing among smallholder farmers

Limited access to timely and adequate information has been identified as a major hindrance to smallholder agriculture in most parts of sub-Saharan Africa. This has negatively affected the socio-economic welfare of smallholder farmers, resulting in high numbers of foodinsecure households. This paper explores the potential value of social interactions between smallholder farmers in improving integrated soil fertility management (ISFM) information and knowledge access and sharing, in the context of field-based learning alliances. With a particular focus on understanding the structural layout of the smallholder social network, the study quantified the connectedness of smallholder farmers along an innovation learning cycle. The study revealed that smallholder farmers within learning alliances had a denser network structure of social interactions. The magnitude of communication efficiency was generally higher for learning alliance participants than non-participants. Field-based learning alliances facilitated improved social interactions, subsequently shortening the innovation dissemination horizon and hence increasing the likelihood of ISFM adoption

Interaction patterns determining improved information and knowledge sharing among smallholder farmers participating in field-based learning alliances in eastern Zimbabwe

Limited access to timely and adequate information has been identified as a major impediment to the growth of smallholder agriculture in most parts of sub-Saharan Africa. This has negatively affected the socio-economic welfare of smallholder farmers resulting in high numbers of food insecure households. The potential of smallholder farmer social interactions for improved integrated soil fertility management (ISFM) information and knowledge access and sharing, was explored by understanding the smallholder social network structural layout and the role of social interactions on innovation learning cycle in the context of field-based learning alliances established by the Soil Fertility Consortium for Southern Africa (SOFECSA). Smallholder farmers within learning alliances had a denser network structure of social interactions. Closeness centrality indices were generally higher for participatory action research (PAR) participants than non-participants suggesting that field-based learning alliances facilitate improved social interactions subsequently shortening the innovation dissemination horizon

From a waste to a valuable resource : combined application of water treatment residual and compost improves maize productivity

Water treatment residual (WTR) is a by-product of municipal clean water treatment which is normally disposed to landfill. WTR production is anticipated to increase as the demand for potable water rises, especially in sub-Saharan Africa (SSA) due to rapid population growth and urbanisation; this has driven municipalities to look for alternative ways to utilise this product and to address SDG12 by reusing wastes in the circular economy. Although significant strides have been made into research on use of WTR as a soil amendment, there are mixed reports on its efficacy at improving either soil structure or plant yield. We do know that nutrients and specifically phosphorus (P) adsorption by both the aluminium (Al) and/or iron (Fe) oxides in WTR, have a deleterious effect on plant growth. We present results on the co-application of WTR with an organic plant based compost together with inorganic P additions in a 5 week greenhouse maize pot trial. There were no significant differences in maize growth and biomass production between the coamendment and sole compost amendments at P < 0.05. Addition of P further increased maize dry matter yield two fold in the co-amendment, a 403% increase compared to the unamended control. Preliminary findings show that WTR can be co-applied with another organic nutrient resource without incurring a yield penalty and thus could be a sustainable option for reusing WTR to enhance environmental protection

Waste to resource: use of water treatment residual for increased maize productivity and micronutrient content

Soil degradation, which is linked to poor nutrient management, remains a major constraint to sustained crop production in smallholder urban agriculture (UA) in sub-Saharan Africa (SSA). While organic nutrient resources are often used in UA to complement mineral fertilizers in soil fertility management, they are usually scarce and of poor quality to provide optimum nutrients for crop uptake. Alternative soil nutrient management options are required. This study, therefore, evaluates the short-term benefits of applying an aluminium-based water treatment residual (Al-WTR), in combination with compost and inorganic P fertilizer, on soil chemical properties, and maize (Zea mays L.) productivity and nutrient uptake. An eight-week greenhouse experiment was established with 12 treatments consisting of soil, Al-WTR and compost (with or without P fertilizer). The co-amendment (10% Al-WTR + 10% compost) produced maize shoot biomass of 3.92 ± 0.16 g at 5 weeks after emergence, significantly (p < 0.05) out-yielding the unamended control which yielded 1.33 ± 0.17 g. The addition of P fertilizer to the co-amendment further increased maize shoot yield by about twofold (7.23 ± 0.07 g). The co-amendment (10% Al-WTR + 10% C) with P increased maize uptake of zinc (Zn), copper (Cu) and manganese (Mn), compared with 10% C + P. Overall, the results demonstrate that combining Al-WTR, compost and P fertilizer increases maize productivity and micronutrient uptake in comparison with single amendments of compost and fertilizer. The enhanced micronutrient uptake can potentially improve maize grain quality, and subsequently human nutrition for the urban population of SSA, partly addressing the UN’s Sustainable Development Goal number 3 of improving diets

Assessment of raw cow milk quality in smallholder dairy farms in Pemba Island Zanzibar, Tanzania

Veterinary Medicine International Volume 2018, Article ID 1031726, 9 pagesMilk quality depends on the physicochemical characteristics, hygienic standards, and nutritional quality; however, animal husbandry practices, unhygienic harvesting and processing, may affect its quality. A cross-sectional study was conducted between August 2010 and July 2011 to assess the hygiene of cow milk production environment, raw cow milk physicochemical characteristics, and microbial quality and estimate the prevalence of antimicrobial residues using standard methods in Pemba Island. A total of 98 raw cow milk samples from selected smallholder dairy farms were analyzed, and the judgement on the quality used the East African Standards. Generally, the milk production chain was done under the unhygienic condition, and dirty plastic containers were used for collection and storage of milk under room temperature. Some milk samples had abnormal colour (2.1%), abnormal smell (7.1%), and pH below normal (35.7%), clotted on alcohol test (9.2%), and had the specific gravity below normal (13.3%). All the milk samples had mineral contents within the recommended range. Milk samples with butterfat below normal were 29.6%, while 14.3% had total solids below recommended values. The mean total viable count (TVC) of milk container surfaces was  log CFU/100 cm2, while total coliform count (TCC) was  log CFU/100 cm2. Up to 55.1% of milk had TVC beyond the recommended levels. The milk mean TVC was  log CFU/ml and TCC was  log CFU/ml. Up to 26.5% of milk samples had the TCC beyond levels. Results on physicochemical characteristics and nutritional analysis show that the raw cow milk in Pemba Island is of inferior quality. Microbiological results of this study imply heavy contaminations of milk. Antimicrobial residues were detected in 83% of the samples and most of them were from Wete District. Unhygienic milk production chain accelerates microbial contaminations, and antimicrobial residues in milk are a big problem that needs urgent attention from the responsible authority

Assessment of raw cow milk quality in smallholder dairy farms in Pemba Island Zanzibar, Tanzania

Veterinary Medicine International Volume 2018, Article ID 1031726, 9 pagesMilk quality depends on the physicochemical characteristics, hygienic standards, and nutritional quality; however, animal husbandry practices, unhygienic harvesting and processing, may affect its quality. A cross-sectional study was conducted between August 2010 and July 2011 to assess the hygiene of cow milk production environment, raw cow milk physicochemical characteristics, and microbial quality and estimate the prevalence of antimicrobial residues using standard methods in Pemba Island. A total of 98 raw cow milk samples from selected smallholder dairy farms were analyzed, and the judgement on the quality used the East African Standards. Generally, the milk production chain was done under the unhygienic condition, and dirty plastic containers were used for collection and storage of milk under room temperature. Some milk samples had abnormal colour (2.1%), abnormal smell (7.1%), and pH below normal (35.7%), clotted on alcohol test (9.2%), and had the specific gravity below normal (13.3%). All the milk samples had mineral contents within the recommended range. Milk samples with butterfat below normal were 29.6%, while 14.3% had total solids below recommended values. The mean total viable count (TVC) of milk container surfaces was  log CFU/100 cm2, while total coliform count (TCC) was  log CFU/100 cm2. Up to 55.1% of milk had TVC beyond the recommended levels. The milk mean TVC was  log CFU/ml and TCC was  log CFU/ml. Up to 26.5% of milk samples had the TCC beyond levels. Results on physicochemical characteristics and nutritional analysis show that the raw cow milk in Pemba Island is of inferior quality. Microbiological results of this study imply heavy contaminations of milk. Antimicrobial residues were detected in 83% of the samples and most of them were from Wete District. Unhygienic milk production chain accelerates microbial contaminations, and antimicrobial residues in milk are a big problem that needs urgent attention from the responsible authority