Browsing by Author "Mukasa, S.B."

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    Changes in Breeding Strategy for Needs in a Liberalized Cotton Industry in Uganda
    (SAARI, 2000) Serunjogi, L.K.; Mukasa, S.B.; Odeke, W.; Ochola, G.
    Commercial cotton (G. hirsutum L.) production has been based on BPA and SATU varieties, grown in two ecological zones. Both have had a strong world market, the stronger, longer and finer fiber BPA finding a different market niche. The collapse of the seed replacement system developed by the Department of Agriculture and liberalization of the cotton industry has resulted in problems of variety deterioration and mixing, leading to non-uniform and poor quality lint. These new challenges necessitated changes in breeding objectives and strategy. In 1993 breeding work was revived at SAARI with the strategy of developing a variety with good adaptation in the two zones for high yield, resistance to pests and high lint quality. Selections were made from existing and purified BPA and SATU stocks, and progenies arising from intraand inter-variety crosses. Variety checks and advanced lines of 9 SATU and 11 BPA stocks were compared, using single and combined analysis of variance over 8 locations and 3 years ordination and cluster analyses. At a three-group level, one group membership was consistent over the three seasons. The members expressed similar response patterns and good yield and constituted the elite entries. G x E interactions were not significant for yield but fiber characteristics of BPA entries were influenced by the environments. SATU and BPA lines performance was comparable except at locations of very low environmental index where SATU was better. Pattern analysis results indicate that the higher quality BPA which is also more bacterial blight resistant, can be grown in a wider range of environments than previously anticipated.
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    Fruit Set and Plant Regeneration in Cassava Following Inter specific Pollination with Castor Bean
    (African Crop Science Journal, 2019) Baguma, J.K.; Mukasa, S.B.; Kawuki, R.; Tugume, A.K.; Buttibwa, M.; Nalela, P.; Eyokia, M.; Oshaba, B.; Ceballos, H.; Lentini, Z.; Baguma, Y.
    The increasing demand for cassava (Manihot esculenta Crantz) for food and non-food uses in the tropics necessitates that its breeding for increased root productivity be made faster. The characteristic long breeding cycle and heterozygous nature of this crop, pose a major obstacle to its rapid genetic improvement. This study aimed at inter-pollinating cassava with castor bean (Ricinus communis), with a purpose of inducing and regenerating cassava doubled haploids (DHs). A total of 3,349 flowers from twelve elite cassava varieties were inter-pollinated with caster bean. A total of 803 fruits were harvested for early embryo rescue and/or ovule culture. Of these, three were dissected to obtain seven unique embryos, while 800 were dissected to obtain 1312 young ovules, all of which were cultured in vitro. Overall, 82 (6.25%) of the cultured ovules formed callus that originated from the embryosac region, which is haploid. Four out of seven rescued embryos (57.1%) regenerated into plantlets. Ploidy analyses of 24 samples using flow cytometry revealed that 23 of the analysed samples were diploid. However, one callus sample was anueploid. Only one sample had an exceptionally high level of homozygosity ( 84.2%). These findings lay a foundation for future research aimed at induction of haploids in cassava.
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    Portable PCR field-based detection of sweetpotato viruses
    (African Crop Science Journal, 2020) Ssengo, J.; Wasswa, P.; Mukasa, S.B.; Okiror, A.; Kyamanywa, S.
    Sweetpotato (Ipomoea batatas Lam.) production is greatly constrained by viral infections, especially Sweet potato feathery mottle virus and Sweet potato chlorotic stunt virus that synergistically cause a severe sweetpotato virus disease. The impact of viruses is aggravated by the vegetative nature of the crop and inaccessibility to dependable diagnostic tools in rural areas where sweetpotato production is done. This makes it hard for seed inspectors to perform quality checks prior to use of vines for planting. The objective of this study was to develop a procedure that allows for detection of sweetpotato viruses on-site. This involved modification of the Lodhi et al. (1994) nucleic acid extraction procedure, by omitting some of the laboratory specific steps and varying the incubation time in liquid nitrogen, instead of the freezer. Incubation in liquid nitrogen for only 1.5 hours yielded as high quality RNA compared to that of the original protocol, when incubation was done at 4°C overnight in a freezer. Reverse transcriptase (RT) was run using a portable miniPCR thermocycler; and the resulting cDNA was amplified using this miniPCR machine instead of using a laboratory stationed conventional PCR thermocycler. The cDNA was efficiently amplified and amplicons were similar to those obtained with the original extraction protocol and subsequent amplification by the conventional RT-PCR. Our protocol reduced extraction time from about 16 hours for the original protocol, to about 2 hours and 45 minutes. If this tool is utilised by the crop protection departments, we believe it will contribute greatly towards sustainable sweetpotato production through making timely recommendations.