Browsing by Author "Tusiime, G."
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Item Banana field resistance to insect-vector transmission of bacterial wilt caused by Xanthomonas campestris p.v musacearum(African Journal of Agricultural Research, 2019) Mudonyi, B.; Vanhaelewyn, L.; Tusiime, G.; Ssekiwoko, F.; Kubiriba, J.; Tushemereirwe, W. K.; Changa, C. M.Banana, a major staple in East and Central Africa is constrained by banana Xanthomonas wilt (BXW) caused by Xanthomonas campestris pv. musacearum (Xcm). Xcm-infected plants are rapidly destroyed leading to 100% yield loss. Cultural controls are effective but laborious attracting laxity among farmers. This has led to epidemic resurgence in areas where BXW had been contained hence spread to new regions. Reliable control option would be planting Xcm-resistant varieties but extensive germplasm evaluation for their identification has not been conducted. Objective therefore was to determine existence of Xcm-resistance in banana by evaluating major banana cloneset representatives among indigenous cultivars plus introduced foreign Musa accessions. Potted plants were artificially inoculated with 0.5 ml (108CFU) of Xcm suspension. Promising selections from pot trial were later evaluated under natural transmission in field. Field trial plants were infected via insect vectors from spreader plants of highly susceptible cv Kayinja infected by spraying flowers with Xcm. Severity of Xcm-infection was semiquantified using scales 1-5 and 0-5 for pot and field screening trials respectively. This enabled calculation of disease index as a measure of resistance for each genotype. High index implied highly susceptible banana genotype and low index resistant genotype. Findings 44 days after artificial inoculation showed wild banana M. balbisiana had 0.0 disease index thus highly resistant. All other banana genotypes tested under similar conditions had disease index of 100 thus susceptible. In field (insect vector transmission), disease index varied significantly among various genotypes evaluated, some susceptible while others; M. balbisiana, Mbwazirume, M9 and M. Zebrina resistant throughout 360 days of observation. We recommend that heritable traits that confer resistance in M. balbisiana, Mbwazirume, M9 and M. zebrina to Xcm be identified for utilization in genetic modification of farmer preferred bananas. Varieties Mbwazirume and M9 should be promoted for farmer growing to complement cultural controls against BXW.Item Banana influences on differential expression of hypersensitive response and pathogenicity gene f (hrpf) in Xanthomonas campestris pv. musacearum(African Journal of Biotechnology, 2017) Mudonyi, B.; Tusiime, G.; Kubiriba, J.; Tushemereirwe, W. K.; Changa, C. M.Banana Xanthomonas wilt is a devastating disease of cultivated banana in East and Central Africa, manifesting as initial leaf wilting, premature fruit ripening and eventual death of all infected plants leading to total yield loss. In order to contribute towards development of effective disease control options, hrpf expression by Xanthomonas campestris pv musacearum (Xcm) during establishment of Xanthomonas wilt infection was determined. To successfully initiate infection, plant pathogenic bacteria deliver effector proteins into host cells using specialized protein transport system such as the Type III secretion system (TTSS). It is a syringe needle-like translocation apparatus essential for delivery of effector proteins into the host cells and hypersensitive response and pathogenicity gene f (hrpf) encodes one of the structural proteins for effector protein delivery. In this study, hrpf expression by Xcm during establishment of Xanthomonas wilt infection was determined in minimal medium amended with extracts from susceptible banana genotypes and banana host plants. Total RNA was isolated from Xcm recovered from inoculated plants and also from minimal medium amended with banana extracts; cDNA synthesised and hrpf amplified by PCR using gene specific primers. Findings showed that Xcm multiplied in susceptible host banana and minimal medium amended with their extracts but not in resistant M. balbisiana and its extract. hrpf gene was thus amplified from cDNA samples of susceptible banana genotypes and their extracts suggesting its expression and involvement in the successful establishment of Xanthomonas wilt disease by Xcm.Item Characterization and Evaluation of Potato Genotypes (Solanum tuberosum L) for Tolerance to Drought in Uganda(American Journal of Potato Research, 2016) Kesiime, V. E.; Tusiime, G.; Kashaija, I. N.; Edema, R.; Gibson, P.; Namugga, P.; Kakuhenzire, R.Potato production in Uganda is being affected by rainfall fluctuations in both timing and amount, resulting into inadequate soil moisture availability and low productivity. Also, potato production is expanding into locations at lower altitudes, where drought is more common. Therefore, drought stress mitigation measures and coping mechanisms need to be devised to face future challenges of climate change, particularly in developing countries to ensure steady supply of adequate quantities of quality food. This study thus, aimed at characterizing new potato clones from CIP (International Potato Center) for tolerance to drought under Ugandan conditions. Consequently a screen house experiment was conducted twice at Kachwekano Zonal Agricultural Research and Development Institute (KAZARDI) from October 2011 to February 2012 and April to July 2012 to evaluate and characterize eight potato genotypes; five of which were obtained from CIP’s breeding collection for drought tolerance and low altitude areas, and three locally released varieties from Uganda. These clones were tested for drought tolerance at three levels of simulated moisture deficit; 25 % field capacity, 50 % and 100 % field capacity (FC). Data were collected on leaf chlorophyll content, relative leaf water content, number of days to 50 % flowering, percent ground cover, leaf area, plant height, number of stems per plant, stem diameter, stress score, increment in plant height after imposing stress, tuber dry matter content and yield components. Of all the traits evaluated, yield and number of days to 50 % flowering contributed most to drought tolerance among the potato genotypes evaluated. There were significant (P ≤ 0.05) differences among genotypes for all evaluated traits. Results from both growth, physiological and yield parameters revealed that the new potato clones were less affected by drought stress compared to adapted varieties. Total tuber yield was 23 tons per hectare, 11.4 and 8.1 in plots at full field capacity, 50 % and 25 % moisture stressed plots respectively in the first experiment. A similar trend was obtained in the second experiment with 19 tons per hectare, 13.7 and 11.3 respectively. The new clones at highest moisture stress had significantly (P ≤ 0.05) higher yields than adapted varieties providing a promise for possible new varieties and breeding stock in extreme conditions of moisture deficit.Item Potential sources of high iron and zinc content in Ugandan bean germplasm(RUFORUM, 2012) Mukamuhirwa, F.; Tusiime, G.; Mukankusi, C.; Gibson, P.; Edema, R.The study was conducted at National Agricultural Research Laboratories (NARL) at Kawanda in order to identify potential sources of high iron and zinc content, Such varieties would contribute to improved health of bean (Phaseolus vulgaris) consumers, who, despite a high consumption of beans, suffer from anemia caused by micronutrient malnutrition (especially iron and zinc). One hundred and eighty seven genotypes from Uganda were screened for iron (Fe) and zinc (Zn) content. The mineral analysis revealed that there was significant (P=0.001) diversity in Fe and Zn content among the Ugandan genotypes with the range of 45 to 87mg/kg of iron and 22 to 40 mg/kg of zinc. Ten Ugandan bean varieties were identified as potential sources of both high iron and zinc content.