Identification of F1 cassava (Manihot esculenta Crantz) progeny using microsatellite markers and capillary electrophoresis

Generation of genetic diversity is necessary in improving on the potential of cassava when faced with various biotic and abiotic challenges. Presently, cassava breeders are breeding for a number of traits, such as drought tolerance, early root bulking, yield, starch, beta-carotene, protein, dry matter, pest and disease resistance, by relying on genetic diversity that exists in manihot esculenta germplasm. Controlled pollination is one of the main methods used to generate genetic diversity in cassava. However, the process of controlled pollination especially in an open field is prone to contamination by illegitimate pollen right from the time of pollination, seed collection, nursery bed establishment to planting of the trials. Therefore, authentication of the progeny obtained from cas-sava crosses is very important for genetic studies. Twelve informative microsatellite markers were used to verify the authenticity of 364 F1 progeny thought to come from four controlled parental crosses. The transmission of each allele at nine microsatellite loci was tracked from parents to progeny in each of the four Namikonga-derived F1 cassava families. Out of the 364 F1 progeny, 317 (87.1%) were true-to-type, 44 (12.1%) were a product of self-pollination and 3 (0.8%) were a product of open pollination. The consistency of the results obtained using microsatellite markers makes this technique a reliable tool for assessing the purity of progeny generated from cassava crosses

Effectiveness of pruning and waxing in reducing postharvest physiological deterioration in Uganda local cassava varieties.

Cassava ( Manihot esculenta Crantz) roots in the fresh form, are susceptible to postharvest physiological deterioration (PPD), thus reducing their economic value and farmer benefits. The objective of this study was to evaluate the effectiveness of pruning and waxing on fresh root storability among cassava varieties in Uganda. Sixteen cassava plants per variety (TME 14, NASE 14, Nyaraboke, Kirimumpale, and Bukalasa) were pruned seven days before harvest, leaving the rest as unpruned controls. After harvest, roots were divided into two portions and one portion was waxed using food grade wax. Pruning alone reduced PPD of stored roots by 23% at day 14 of storage; and by 19% at day 28 compared with the control. Pruning as a treatment resulted into increased sugar content, ranging 9-30%), and significant (P<0.05) losses in starch yield. Pruning combined with waxing, resulted in a reduction of up to 43% in PPD by day 14, and up to 67 at day 28. Reduction in carbohydrate (starch) was not significant (P>0.05) under the pruning and waxing treatment, which had minor effects on stored root composition. The results indicate that pruning is appropriate for the short-term storage of fresh cassava roots for up to 14 days. Waxing, combined with pruning, is suitable for longer term storage up to 28 days under Uganda conditions.Les racines de manioc ( Manihot esculenta Crantz) \ue0 l\u2019\ue9tat frais sont sensibles \ue0 la d\ue9t\ue9rioration physiologique apr\ue8s la r\ue9colte, r\ue9duisant ainsi leur valeur \ue9conomique et les avantages pour les agriculteurs. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer l\u2019efficacit\ue9 d\u2018 \ue9laguer et de cirer sur la capacit\ue9 de stockage des racines fra\ueeches parmi les vari\ue9t\ue9s de manioc en Ouganda. Seize plants de manioc par vari\ue9t\ue9 (TME 14, NASE 14, Nyaraboke, Kirimumpale et Bukalasa) ont \ue9t\ue9 \ue9lagu\ue9s sept jours avant la r\ue9colte, les autres \ue9tant des t\ue9moins non \ue9lagu\ue9s. Apr\ue8s la r\ue9colte, les racines ont \ue9t\ue9 divis\ue9es en deux parties et une partie a \ue9t\ue9 cir\ue9e avec de la cire de qualit\ue9 alimentaire. L\u2019\ue9lagage seul r\ue9duisait la PPD des racines stock\ue9es de 23% au 14e jour de stockage; et de 19% au 28e jour compar\ue9 au t\ue9moin. L\u2019\ue9lagage en tant que traitement a entra\ueen\ue9 une augmentation de la teneur en sucre (comprise entre 9 et 30%) et une perte significative (P <0,05) du rendement en amidon. La combinaison d\u2018 \ue9laguer et de cirer a entra\ueen\ue9 une r\ue9duction de la PPD de 43% au 14e jour et de 67 ans au 28e jour. La r\ue9duction de la teneur en glucides (amidon) n\u2019\ue9tait pas significative (P> 0,05) dans le cadre des traitements d\u2018 \ue9laguer et de cirer a eu des effets mineurs sur la composition des racines stock\ue9es. Les r\ue9sultats indiquent que l\u2018\ue9laguage convient au stockage \ue0 court terme de racines de manioc fra\ueeches pendant 14 jours au maximum. La combinaison d\u2018 \ue9laguer et de cirer convient au stockage \ue0 long terme jusqu\u2019\ue0 28 jours dans les conditions ougandaises

Relationship between malaria infection intensity and rainfall pattern in Entebbe peninsula, Uganda

Background: This study was to assess malaria prevalence in relation to rainfall pattern in different localities of Entebbe Municipality, Uganda. A cross sectional study was conducted amongst the local community residing in the area from January 2003 to January 2004 to investigate the incidence and intensity of malaria infection. Methods: Thick and thin blood smears were made from each patient with fever (body temperature &#8805; 37.5° C). The slides were examined microscopically for malaria parasites. A total of 616 residents aged 2 to 50 years were registered in the study by name, age, sex and residential location. Spearman correlation coefficient (r) was used to evaluate relationship between parasite density, age and body temperature on one hand and rainfall plus parasite density on the other hand. Results: A direct relationship was observed between malaria transmission and monthly rainfall in Entebbe Municipality. About 69.8% of the patients had fever. Parasite density fluctuated according to monthly rainfall pattern. Two peaks of high parasite density was observed, each peak coinciding with a peak rainfall pattern of the bimodal annual rain seasons. There was a negative but significant correlation (r = -0.09271; p < 0.0214) between parasite density and age, suggesting that mature individuals clear parasites more effectively than children. Furthermore, we observed a bimodal peak of mean parasite density in children and adults; peak in children is higher than of adults, each peak coinciding with rainfall pattern. There is also a significant positive correlation between parasite density and body temperature (r = 0.1927; p = 0.0001). However, there is no significant variation in mean parasite densities in the different locations of Entebbe Municipality. Conclusions: Our study confirms rainfall pattern and age influence parasite density and are important determinants of malaria infection and transmission in Entebbe Municipality. Increased parasite density in children is a useful indicator for monitoring intensity of infection. This information is valuable in policy formulation for control of malaria during periods of intense transmission African Health Sciences Vol. 5 (3) 2005: pp. 235-24

Relationship between malaria infection intensity and rainfall pattern in Entebbe peninsula, Uganda

Background: This study was to assess malaria prevalence in relation to rainfall pattern in different localities of Entebbe Municipality, Uganda. A cross sectional study was conducted amongst the local community residing in the area from January 2003 to January 2004 to investigate the incidence and intensity of malaria infection. Methods: Thick and thin blood smears were made from each patient with fever (body temperature ≥ 37.5° C). The slides were examined microscopically for malaria parasites. A total of 616 residents aged 2 to 50 years were registered in the study by name, age, sex and residential location. Spearman correlation coefficient (r) was used to evaluate relationship between parasite density, age and body temperature on one hand and rainfall plus parasite density on the other hand. Results: A direct relationship was observed between malaria transmission and monthly rainfall in Entebbe Municipality. About 69.8% of the patients had fever. Parasite density fluctuated according to monthly rainfall pattern. Two peaks of high parasite density was observed, each peak coinciding with a peak rainfall pattern of the bimodal annual rain seasons. There was a negative but significant correlation (r = -0.09271; p < 0.0214) between parasite density and age, suggesting that mature individuals clear parasites more effectively than children. Furthermore, we observed a bimodal peak of mean parasite density in children and adults; peak in children is higher than of adults, each peak coinciding with rainfall pattern. There is also a significant positive correlation between parasite density and body temperature (r = 0.1927; p = 0.0001). However, there is no significant variation in mean parasite densities in the different locations of Entebbe Municipality. Conclusions: Our study confirms rainfall pattern and age influence parasite density and are important determinants of malaria infection and transmission in Entebbe Municipality. Increased parasite density in children is a useful indicator for monitoring intensity of infection. This information is valuable in policy formulation for control of malaria during periods of intense transmission