Browsing by Author "Ochwo- Ssemakula, Mildred"

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    Genetic diversity and population structure of Peronosclerospora sorghi isolates of Sorghum in Uganda
    (International Journal of Environment, Agriculture and Biotechnology (IJEAB), 2018) Kumi, Frank; Agbahoungba, Symphorien; Badji, Arfang; Mwila, Natasha; Ibanda, Angele; Anokye, Michael; Odong, Thomas; Wasswa, Peter; Ochwo- Ssemakula, Mildred; Tusiime, Geoffrey; Biruma, Moses; Kassim, Sadik; Rubaihayo, Patrick
    Sorghum is the third most important staple cereal crop in Uganda after maize and millet. Downy mildew disease is one of the most devastating fungal diseases which limits the production and productivity of the crop. The disease is caused by an obligate fungus, Peronosclerospora sorghi (Weston & Uppal) with varying symptoms. Information on the genetic diversity and population structure of P.sorghi in sorghum is imperative for the screening and selection for resistant genotypes and further monitoring possible mutant(s) of the pathogen. Isolates of P. sorghi infecting sorghum are difficult to discriminate when morphological descriptors are used. The use of molecular markers is efficient, and reliably precise for characterizing P. sorghi isolates. This study was undertaken to assess the level of genetic diversity and population structure that exist in P. sorghi isolates in Uganda.
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    Molecular diagnostics of groundnut rosette disease agents in Uganda: Implications on epidemiology and management of groundnut rosette disease
    (Journal of plant breeding and crop science, 2017) Kalule Okello, David; Adrogu Ugen, Michael; Tukamuhabwa, Phinehas; Ochwo- Ssemakula, Mildred; Lapaka Odong, Thomas; Adriko, John; Kiconco, Faith; Male, Allan; Deom, Carl Michael
    The objective of this study was to use molecular diagnostic tools to detect the agents of groundnut rosette disease (GRD) to guide in varietal development and disease management. Samples were collected from both GRD infected and healthy plants and sites geo-referenced. RNA extraction, cDNA synthesis, polymerase chain reaction (PCR) amplification, electrophoresis, staining and visualization were performed according to standard procedures. Molecular diagnosis of the samples showed various combinations of the GRD agents, some in isolation and others a combination of two or three agents. This distribution is attributed to dependence on the aphid feeding behaviour and pathogenicity of GRD agents. Chlorotic and green rosette symptoms were observed throughout the sampling sites signifying the presence of satellite RNA (sat-RNA) variants. Some plants showing GRD symptoms tested negative for GRD, whereas some healthy-looking plants tested positive for the GRD complexes pointing to the ineffectiveness of phenotypic screening and the need for a molecular diagnostic tool that detects all three GRD agents both in absence or presence of disease symptoms. The absence of groundnut rosette assistor virus (GRAV) in some symptomatic samples signifies that they are epidemiologically dead end sources since GRV and sat-RNA must be packaged within the GRAV coat protein to be aphid transmissible. Oyado (Cassia obtusifolia) tested positive for all the GRD agents making it a potential alternative host. There is an urgent need for validation of the phenotypic screening with molecular tools in efficient diagnosis of the multi-pathogenic GRD in guiding both plant breeding and pathology work.