Browsing by Author "Tukamuhabwa, Phinehas"
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Item Continuous Storage Root Formation and Bulking in Sweet potato(Gates Open Research, 2019) Bararyenya, Astere; Tukamuhabwa, Phinehas; Gibson, Paul; Grüneberg, Wolfgang; Ssali, Reuben; Low, Jan; Odong, Thomas; Ochwo-Ssemakula, Mildred; Talwana, Herbert; Mwila, Natasha; Mwanga, RobertSweetpotato (Ipomoea batatas (L.) Lam, family Convolvulaceae.) is one of the most important food crops worldwide, with approximately 106 million tons produced in almost 120 countries from an area of about 8 million ha and an average global yield of 11.1 tons/ha (FAO, 2016). Asia is the world’s largest sweetpotato producing continent, with 79 million tons, followed by Africa (FAOstat, 2016). About 75% of this global production is from China alone. A total of 21.3 million tons is produced in Africa, with 48% from the Great Lakes region. In East Africa, the crop is the second most important root crop after cassava and has played an important role as a famine-relief crop during its long history and has recently been reevaluated as a health-promoting food (Low et al., 2017). Uganda ranks as the fourth largest sweetpotato producer in the world after China, Nigeria and Tanzania, with a production of 2.1 million t. In Africa, Uganda is ranked third after Nigeria and Tanzania. Sweetpotato is one of the main staple crops in the food systems of Uganda, Rwanda, and Burundi with a per capita consumption of 50.9, 80.1 and 57.0 kg, respectivelyItem Evaluation of Cowpea Genotypes for Virus Resistance Under Natural Conditions in Uganda(Journal of Agricultural Science, 2014) Mbeyagala, Emmanuel K.; Mukasa, Blasio S.; Tukamuhabwa, Phinehas; Bisikwa, JenipherCowpea (Vigna unguiculata L. Walp) is an important grain legume in most parts of Sub Saharan Africa. However, viral diseases are a major limiting production factor causing significant yield losses. An experiment was conducted to evaluate the reaction of 105 different cowpea genotypes to viral infection in different agro-ecological zones of Uganda. The aim was to identify genotypes that could serve as sources of resistance to virus infection. Virus infection in these experiments occurred naturally through insect vectors. Results showed that there were significant differences in disease reaction among genotypes within and among agro-ecological zones in terms of Area Under Disease Progress Curve (AUDPC) and incidence. Interactions of genotype by season (GXS), genotype by location (GXL) and genotype by location by season (GXLXS) also significantly affected reaction to viral infection among genotypes. Introduced cowpea genotypes exhibited a more susceptible viral disease reaction compared to the landraces over the two seasons in the three locations. A number of landraces such as WC32, WC18, NE43, NE15, WC35B consistently showed resistance to virus infection in the three locations and therefore could be good sources of resistance. Low disease pressure (AUDPC) was also recorded on SECOW2W (released variety) as reported by previous studies. The landraces also gave consistently higher grain yield values compared to the introduced genotypes. Overall, data from this study showed that locally adapted cowpea genotypes offer resistance to virus infection and may be desirable germplasm for Ugandan cowpea breeding programs.Item Evaluation of the American Yam Bean (Pachyrhizus spp.) for Storage Root Yield Across Varying Eco-geographic Conditions in Uganda(Journal of Agricultural Science, 2019) Andiku, Charles; Tukamuhabwa, Phinehas; Mukasa Ssebuliba, James; Talwana, Hebert; Tumwegamire, Silver; Grüneberg, Wolfgang J.The American yam bean (Pachyrhizus spp.) is a legume crop that is exclusively used for its storage roots. The seeds are inedible due to presence of toxic rotenone. It produces high storage root yields comparable of major root crops like cassava or sweetpotato. And flower pruning more than doubles its root yield performance. Using twenty five yam bean accessions, the current study aimed to determine root yield stability and adaptability, and presence of yam bean production mega environments in Uganda. Trials were planted at three stations, Namulonge, Serere, and Kachwekano during two consecutive seasons of 2011. Fresh storage root yields were significantly different (p < 0.05) across locations with the ideal location being Namulonge (fresh storage root yield of 10.1 t ha-1), followed by Serere (8.0 t ha-1), and Kachwekano (3.1 t ha-1). Results of AMMI analysis indicated the presence of genotype-by-environment interaction for fresh storage root yield. Through AMMI estimates and GGE visual assessment, genotype 209017 was the highest yielding with mean yield of 20.7 t ha-1. Genotype 209018 with mean yield of 15.5 t ha-1 was the most stable and adapted accession in the entire discriminating environment in Uganda. From the environmental focusing plot, the six environments were grouped into two putative mega environments for yam bean production.Item Genetic Diversity and Population Structure Analysis of Tropical Soybean (Glycine Max (L.) Merrill) using single Nucleotide Polymorphic Markers(Global Journal of Science Frontier Research, 2020) Obua, Tonny; Sserumaga, Julius P.; Opiyo, Stephen O.; Tukamuhabwa, Phinehas; Odong, Thomas L.; Mutuku, Josiah; Yao, NasserSoybean (Glycine max (L.) Merrill) is among the most important crops worldwide due to its numerous uses in feed, food, biofuel, and significant atmospheric nitrogen fixation capability. To understand the genetic diversity and population structure of tropical soybean germplasm, 89 genotypes from diverse sources were analyzed using 7,962 SNP markers. The AMOVA results showed low diversity among and high within the populations, while the polymorphism information content (PIC) was 0.27. Both phylogenetic and principal component analysis grouped the 89 soybean genotypes into three major clusters, while population structure grouped the soybean genotypes into two subpopulations. On the other, the average Roger genetic distances within the study population was 0.34. The low diversity reported in the studied soybean germplasm pool is particularly worrying, considering the new trends of climate change and the emergence of new pests and diseases of soybean. Therefore, in order to address these challenges and develop soybean varieties with desirable traits, there is a need to broaden the genetic base of tropical soybean through the importation of germplasm from other countries.Item Genetic variation, Heritability estimates and GXE effects on yield traits of Mesoamerican common bean (Phaseolus vulgaris L) germplasm in Uganda(Plant Genetic Resources, 2018) Okii, Dennis; Mukankusi, Clare; Sebuliba, Sulaiman; Tukamuhabwa, Phinehas; Tusiime, Geoffrey; Talwana, Herbert; Odong, Thomas; Namayanja, Annet; Paparu, Pamela; Nkalubo, Stanley; Otim, Michael; Ugen, Michael; Buah, Stephen; Gepts, PaulGermplasm of common beans from the Mesoamerican gene pool races: Durango, Jalisco, Mesoamerica and Guatemala have highest genetic variation for the crop’s improvement. The objective was to assign 50 common bean germplasm in Uganda into its gene pool races based on analyses of population structure. Secondly, to estimate heritability and effects of genotype environment (GXE) interaction on common bean agronomic and yield traits in space and time. Sample genomic DNA was amplified in 2011 with 22 Simple sequence repeat markers (SSRs) and alleles separated using capillary electrophoresis. Field evaluations were conducted in 2010 and 2011 at NaCRRI and 2015 at CIAT – Kawanda. Multivariate analyses of SSRs data identified four subgroups within the germplasm: K4.1–K4.4, with corresponding Wrights fixation indices (FST) as 0.1829 for K4.1, 0.1585 for K4.4, 0.1579 for K4.2 and least for K4.3 at 0.0678. Gene pool race admixtures in the population (14%) were notable and attributed to gene flow. Four superior parents currently used in improving resistance to major diseases grouped as; Jalisco for MLB49-89A; Mesoamerica for MCM5001 and G2333; Durango for MEXICO 54. Heritability values for yield traits estimated using phenotypic data from above fixed parents, was above 0.81. Season and location had significant effect (P < 0.05) on numbers of: flower buds per inflorescence, pod formation and weight of 100 seeds. The findings will improve understanding of co-evolutionary relationships between bean hosts and pathogens for better disease management and will broaden the germplasm base for improving other tropical production constraints.Item Genome-wide association study identified candidate genes controlling continuous storage root formation and bulking in hexaploid sweetpotato(BMC plant biology, 2020) Bararyenya, Astère; Olukolu, Bode A.; Tukamuhabwa, Phinehas; Grüneberg, Wolfgang J.; Ekaya, Wellington; Low, Jan; Ochwo-Ssemakula, Mildred; Odong, Thomas L.; Talwana, Herbert; Badji, Arfang; Kyalo, Martina; Nasser, Yao; Gemenet, Dorcus; Kitavi, Mercy; Mwanga, Robert O. M.Continuous storage root formation and bulking (CSRFAB) in sweetpotato is an important trait from agronomic and biological perspectives. Information about the molecular mechanisms underlying CSRFAB traits is lacking. Results: Here, as a first step toward understanding the genetic basis of CSRFAB in sweetpotato, we performed a genome-wide association study (GWAS) using phenotypic data from four distinct developmental stages and 33,068 single nucleotide polymorphism (SNP) and insertion-deletion (indel) markers. Based on Bonferroni threshold (pvalue < 5 × 10− 7), we identified 34 unique SNPs that were significantly associated with the complex trait of CSRFAB at 150 days after planting (DAP) and seven unique SNPs associated with discontinuous storage root formation and bulking (DCSRFAB) at 90 DAP. Importantly, most of the loci associated with these identified SNPs were located within genomic regions (using Ipomoea trifida reference genome) previously reported for quantitative trait loci (QTL) controlling similar traits. Based on these trait-associated SNPs, 12 and seven candidate genes were respectively annotated for CSRFAB and DCSRFAB traits. Congruent with the contrasting and inverse relationship between discontinuous and continuous storage root formation and bulking, a DCSRFAB-associated candidate gene regulates redox signaling, involved in auxin-mediated lateral root formation, while CSRFAB is enriched for genes controlling growth and senescence. Conclusion: Candidate genes identified in this study have potential roles in cell wall remodeling, plant growth, senescence, stress, root development and redox signaling. These findings provide valuable insights into understanding the functional networks to develop strategies for sweetpotato yield improvement. The markers as well as candidate genes identified in this pioneering research for CSRFAB provide important genomic resources for sweetpotato and other root crops.Item Genotype by environment effects on promiscuous nodulation in soybean (Glycine max L. Merrill)(Agriculture & Food Security, 2017) Agoyi, Eric E.; Odong, Thomas L.; Tumuhairwe, John B.; Chigeza, Godfree; Diers, Brian W.; Tukamuhabwa, PhinehasUnderstanding factors influencing the expression of a trait is key in designing a breeding program. Genotype by environment interaction has great influence on most quantitative traits. Promiscuous nodulation is a trait of importance for soybean production in Africa, because of the soil bacteria Bradyrhizobium japonicum not being indigenous in most African soils. Most soybean cultivars require B. japonicum for nodulation leading to the need for seed inoculation before sowing soybean in Africa. Few cultivars have capability to nodulate with Bradyrhizobia spp. that are different from B. japonicum and native in African soils. Such cultivars are termed “promiscuous cultivars.” Field experiments were conducted in six locations in Uganda for two seasons, to investigate the extent of environmental influences on the nodulation ability of promiscuous soybean genotypes. Results: Additive main effect and multiplicative interaction effects showed highly significant environment and genotype by environment (G × E) interaction effects on all nodulation traits. G × E interaction contributed more to the total variation than genotypes. The genotypes Kabanyolo I and WonderSoya were the most stable for nodules’ dry weight (NDW), which is the nodulation trait the most correlated with grain yield. Genotype UG5 was the most stable for nodules’ number (NN), and Nam II for nodules’ effectiveness (NE). The genotype NamSoy 4M had the highest performance for NN, NFW, and NDW, but was less stable. WonderSoya had the highest NE. Genotype and genotype by environment analysis grouped environments into mega-environments (MEs), and four MEs were observed for NDW, with NamSoy 4M the winning genotype in the largest ME, and Kasese B the ideal environment for that nodulation trait. Conclusion: This study provides information that can guide breeding strategies. The low genetic effect that led to high environmental and G × E interaction effects raised the need for multi-environments testing before cultivar selection and recommendation. The study revealed genotypes that are stable and others that are high performing for nodulation traits, and which can be used as parental lines in breeding programs.Item Identification and mapping of quantitative trait loci associated with soybean rust (Phakopsora pachyrhizi) resistance in genotype UG 5(African Journal of Biotechnology, 2018) Gebremedhn, Hailay Mehari; Msiska, Ulemu Mercy; Weldekidan, Miesho Belay; Abate Asmamaw, Fentaw; Winnifred, Akech; Onziga, Dramadri Isaac; Lapaka Odong, Thomas; Rubaihayo, Patrick; Tukamuhabwa, PhinehasSoybean rust, Phakopsora pachyrhizi, is one of the most serious and widespread foliar diseases of soybean causing high yield losses world-wide. The objective of this study was to identify and map quantitative trait loci (QTLs) resistant to soybean rust in genotype UG 5. Ninety-seven F2 mapping plants, obtained from a cross between Wondersoya and UG 5, were used for this study. Quantitative trait locus analysis using QTL IciMapping software identified three putative QTLs associated with soybean rust (SBR) on chromosomes 6, 9 and 18 with logarithms of odds (LOD) scores ranging from 3.47 to 8.23 and phenotypic variance explained by the QTLs ranging from 18.3 to 25.6%. The putative QTL detected on chromosome 9 is novel and has not been reported elsewhere. The putative QTLs identified in this study could help to facilitate SBR resistance breeding towards efficient marker assisted selection approach and gene pyramiding leading to the development of durable resistance.Item Influence of environment on soybean [Glycine max (L.) Merr.] resistance to groundnut leaf miner, Aproaerema modicella (Deventer) in Uganda(Journal of Plant Breeding and Crop Science, 2018) Pembele Ibanda, Angele; Karungi, Jeninah; Malinga, Geoffrey Maxwell; Adjumati Tanzito, Georges; Ocan, David; Badji, Arfang; Mwila, Natasha; Lapaka Odong, Thomas; Tukamuhabwa, Phinehas; Rubaihayo, PatrickGroundnut leaf miner (GLM) [Aproaerema modicella (Deventer)] is a serious problem for soybean cultivation in Uganda causing yield losses of up to 100%. The use of soybean [Glycine max (L.) Merr.] cultivars resistant to GLM attack is an important strategy in the integrated pest management program. The aim of this study was to determine the environment × genotype interaction influence on the soybean resistance traits to GLM attack. Eighteen soybean genotypes were evaluated for resistance to GLM attack. The experiment was set up using randomized complete block design replicated three times under natural pest infestation in Budaka (Eastern) and Arua (Northern) districts in Uganda. Data were subjected to analysis of variance, Pearson’s phenotypic correlation and cluster analysis. Highly significant (p < 0.001) differences among the genotypes were recorded for all the studied traits, except the number of pupae per plant which was significant (p < 0.05). GLM incidence and severity had significant negative correlations with rainfall and relative humidity. However, there were significant positive correlations between minimum temperature and GLM incidence as well as severity for most of the genotypes. Soybean genotypes VI046160 and VI046167 could be used as parents in breeding for resistance to GLM pest. Areas with high rainfall and humidity would be recommended for soybean production to minimize infestation by GLM.Item Influence of environment on soybean [Glycine max (L.) Merr.] resistance to groundnut leaf miner, Aproaerema modicella (Deventer) in Uganda(Journal of Plant Breeding and Crop Science, 2018) Pembele Ibanda, Angele; Karungi, Jeninah; Malinga, Geoffrey Maxwell; Adjumati Tanzito, Georges; Ocan, David; Badji, Arfang; Mwila, Natasha; Lapaka Odong, Thomas; Tukamuhabwa, Phinehas; Rubaihayo, PatrickGroundnut leaf miner (GLM) [Aproaerema modicella (Deventer)] is a serious problem for soybean cultivation in Uganda causing yield losses of up to 100%. The use of soybean [Glycine max (L.) Merr.] cultivars resistant to GLM attack is an important strategy in the integrated pest management program. The aim of this study was to determine the environment × genotype interaction influence on the soybean resistance traits to GLM attack. Eighteen soybean genotypes were evaluated for resistance to GLM attack. The experiment was set up using randomized complete block design replicated three times under natural pest infestation in Budaka (Eastern) and Arua (Northern) districts in Uganda. Data were subjected to analysis of variance, Pearson’s phenotypic correlation and cluster analysis. Highly significant (p < 0.001) differences among the genotypes were recorded for all the studied traits, except the number of pupae per plant which was significant (p < 0.05). GLM incidence and severity had significant negative correlations with rainfall and relative humidity. However, there were significant positive correlations between minimum temperature and GLM incidence as well as severity for most of the genotypes. Soybean genotypes VI046160 and VI046167 could be used as parents in breeding for resistance to GLM pest. Areas with high rainfall and humidity would be recommended for soybean production to minimize infestation by GLM.Item Inheritance of soybean resistance to soybean rust in Uganda’s soybean germplasm(International Journal of Agronomy and Agricultural Research, 2018) Gebremedhn, Hailay Mehari; Belay Weldekidan, Miesho; Msiska, Ulemu Mercy; Asmamaw, Fentaw Abate; Lapaka Odong, Thomas; Tukamuhabwa, Phinehas; Rubaihayo, PatrickUnderstanding the genetic mechanisms of soybean rust resistance is important for effective selection and breeding procedures. This study was hence conducted to determine the combining ability and gene action controlling soybean rust using a 10x10 half diallel mating design. The F2 segregating populations along with their parents were evaluated for rust severity and sporulation level at two reproductive stages (R4 and R6) in screen house and field conditions during the second season of 2016 and first season of 2017 at MUARIK using an alpha lattice design replicated thrice. Significant differences were observed among the parents and F2 generations for both disease severity and sporulation level. General and specific combining abilities were highly significant. The GCA/SCA ratio (1.50-2.30) and the Baker’s ratio (0.75-0.82) showed the predominance of additive gene action in the inheritance of soybean rust resistance. The broad-sense (0.94-0.99) and narrow-sense (0.73-0.82) heritability estimates indicated the possibility of improving resistance to soybean rust through selection in the early generations. UG 5, Maksoy 3N, Maksoy 4N and Maksoy 5N had negative GCA effects. The F2 populations derived from these parents crossed with Wonder soya and Nam 2 had also negative SCA effects. The use of these parents and F2 populations can, therefore, increase the response to selection for improving resistance to soybean rust.Item Mode of inheritance of promiscuous nodulation and combining abilities in soybean genotypes(International Journal of Agronomy and Agricultural Research (IJAAR), 2016) Agoyi, Eric E.; Mohammed, Khalid E.; Odong, Thomas L.; Tumuhairwe, John B.; Chigeza, Godfree; Tukamuhabwa, PhinehasKnowledge of the mode of inheritance of a trait can be a powerful decision-making tool in a breeding program, as it helps predicting selection gain, defining breeding strategy and choosing parental lines. This study aimed at estimating genetic parameters to infer the mode of inheritance of promiscuous nodulation in soybean. Half diallel crosses were made among nine parental lines. F2 progenies were field evaluated together with parents for nodulation characteristics and grain yield in response to Bradyrhizobium sp. strain USDA 3456. Data on nodule number (NN), percent of effective nodules (NE), fresh and dry weight of nodules (NFW and NDW), and grain yield were subjected to analysis of variance, and progenies’ means regression against parents’ was performed following Griffing’s Method2/Model 1. General and specific combining abilities, broad and narrow sense heritabilities, and Baker’s ratio were estimated. The study showed predominant GCA effect for all measured traits except NE. Broad and narrow sense heritabilities were high for grain yield and NDW, moderate for NN and NFW, and low for NE. Baker’s ratio was high for all measured traits except for NE. Overall, additive gene action was more important for all measured traits, except NE where non-additive gene action was more important. The high to moderate heritabilities for most traits showed that substantial gain can be achieved through selection.Item 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 MichaelThe 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.Item Multi-Environmental Evaluation of Protein Content and Yield Stability among Tropical Soybean Genotypes Using GGE Biplot Analysis(Agronomy, 2021) Obua, Tonny; Sserumaga, Julius Pyton; Awio, Bruno; Nganga, Fredrick; Odong, Thomas L.; Tukamuhabwa, Phinehas; Tusiime, Geoffrey; Mukasa, Settumba B.; Nabasirye, MargaretThe yield and protein performance in a soybean genotype result from its interaction with the prevailing environmental conditions. This makes selecting the best genotypes under varied target production environments more complex. This study’s objectives were to determine protein content and protein stability of 30 elite soybean genotypes in major soybean-growing areas of Uganda, assess the yield performance and stability in soybeans and determine the relationship between the protein content and grain yield in soybeans. The genotypes were planted in a randomized complete block design of three replications for six seasons across eight locations in Uganda. Genotype and genotypeby- environment (GGE) biplot analyses classified the test locations into three mega-environments for soybean protein and grain yields. Genotype NII X GC 20.3 had the highest mean protein content of 43.0%, and BSPS 48A-9-2 and BSPS 48A-28 were superior for the mean grain yield (1207 kg ha1). Bulindi was the most discriminating and representative test environment for soybean yield. A weak and negative correlation (r = 0.1**, d.f. = 29) was detected between the protein content (%) and yield (kg ha1). The highest-yielding genotypes BSPS 48A-9-2, BSPS 48A-31, and Nam II GC 44.2 are recommended for further evaluation under farmers’ production conditions for selection and release as new soybean varieties in Uganda.Item Physicochemical Characteristics of Yam Bean (Pachyrhizus erosus) Seed Proteins(Journal of Food Research, 2014) Kisambira, Abbas; Muyonga, John H.; Byaruhanga, Yusuf B.; Tukamuhabwa, Phinehas; Tumwegamire, Silver; Gruenberg, WolfgangThis study sought to determine the physicochemical and functional properties of yam bean (Pachyrhizus erosus) seed proteins. Pachyrhizus erosus seeds from two accessions (UYB 06 and UYB 07) were milled into flours and then defatted. A portion of the defatted flour was used for production of protein isolates and protein fractions. The physicochemical and functional properties, in vitro digestibility and electrophoretic pattern of the flour and protein isolate were determined. The results showed that albumins (53.3%) were the dominant protein fraction followed by globulins (18.7%), glutelins (8.8%) and prolamins (2.7%). Regarding functional properties, the Pachyrhizus erosus seed protein isolates exhibited 8% of least gelation concentration, water absorption capacity of 3.0 g g-1, oil absorption capacity of 0.8 g g-1, protein solubility of 81.0%, foaming capacity of 37.1%, foam stability of 73.8%, emulsion activity of 13.8% and emulsion stability of 9.2%. In vitro protein digestibility of the raw and cooked beans was 87.6% and 84.3%, respectively. The electrophoretic pattern of Pachyrhizus erosus protein showed major bands corresponding to molecular weight 13.3, 15, 29.8, 54.4 and above 84.7 kDa. The results, suggest that Pachyrhizus erosus seed protein has potential for use in both food and non-food applications such as films and coating.Item Prediction of candidate genes associated with resistance to soybean rust (Phakopsora pachyrhizi) in line UG-5(Plant Breed, 2020) Gebremedhn, Hailay M.; Msiska, Ulemu M.; Weldekidan, Miesho B.; Odong, Thomas L.; Rubaihayo, Patrick; Tukamuhabwa, PhinehasOnline databases containing genetic information are crucial to extract new candidate genes from existing data and web-based resources. The objective of this study was, therefore, to predict putative candidate genes associated with resistance to SBR in line UG-5 and understand their functions using different bioinformatics tools from the online available databases. The physical positions for the flanking markers of the identified putative QTLs were searched on the SoyBase database genome browser based on Glyma 1.01 assembly. The putative candidate genes and annotated functions of the surrounding genes were discovered in the vicinity using SoyBase and Phytozome databases. A total of 18 putative candidate genes were predicted on approximately 482.7 kb region of QTL-3 (chromosome 18), among which, six putative candidate genes were found to encode leucine-rich repeat (LRR), Ser/Thr protein phosphatase, leucine-rich repeat receptor-like protein kinase (LRR-RLK) and chitinase- related proteins, which are associated with plant defence signalling pathways. Moreover, F-box and leucine-rich repeat, glycosyltransferase family member and serine/threonine-protein phosphatase 2A catalytic subunit coding genes were predicted on the novel putative QTL detected on chromosome 9. This information could, therefore, be used for further prediction and annotation of candidate genes from sequenced regions of line UG-5 as these putative candidate genes were predicted from the Glyma 1.01 assembly.Item Recombination fraction and genetic linkage among key disease resistance genes (Co-42/Phg-2 and Co-5/“P.ult”) in common bean(African journal of biotechnology, 2019) Okii, Dennis; Badji, Arfang; Odong, Thomas; Talwana, Herbert; Tukamuhabwa, Phinehas; Male, Allan; Mukankusi, Clare; Gepts, PaulAnthracnose (Colletotrichum lindemuthianum), Angular leaf spot (Pseudocercospora griseola) and Pythium root rot are important pathogens affecting common bean production in the tropics. A promising strategy to manage these diseases consists of combining several resistance (R) genes into one cultivar. The aim of the study was to determine genetic linkage between gene pairs, Co-42/Phg-2, on bean-chromosome Pv08 and Co-5/“P.ult” on-chromosome Pv07, to increase the efficiency of dual selection of resistance genes for major bean diseases, with molecular markers. The level of recombination was determined by tracking molecular markers for both BC3F6 and F2 generations. Recombination fraction r, among gene pairs, the likelihood of linkage, L(r), and logarithm of odds (LOD) scores were computed using the statistical relationship of likelihood which assumes a binomial distribution. The SCAR marker pair SAB3/PYAA19 for the gene pair Co-5/“P.ult” exhibited moderate linkage (r = 32 cM with a high LOD score of 9.2) for BC3F6 population, but relatively stronger linkage for the F2 population (r = 21 cM with a high LOD score of 18.7). However, the linkage among SCAR marker pair SH18/SN02, for the gene pair Co-42/Phg-2 was incomplete for BC3F6 population (r = 47 cM with a low LOD score of 0.16) as well as F2 population (r = 44 cM with a low LOD score of 0.7). Generally, the weak or incomplete genetic linkage between marker pairs studied showed that all the four genes mentioned earlier have to be tagged with a corresponding linked marker during selection. The approaches used in this study will contribute to two loci linkage mapping techniques in segregating plant populations.Item Responses to selection for yield traits and key diseases among common bean genetic pyramids across locations(Journal of Crop Improvement, 2019) Okii, Dennis; Badji, Arfang; Odong, Thomas; Talwana, Herbert; Tukamuhabwa, Phinehas; Magdalena, William; Gepts, Paul; Mukankusi, ClareKnowledge of response to selection (R) helps to analyze the efficiency of crop-improvement programs and devise appropriate selection strategies. The objective of this study was to determine response to selection of common bean (Phaseolus vulgaris L.) genetic pyramids for diseases and yield traits. Populations evaluated included pyramided parents, climbing pyramided progenies, and checks. The trial was planted in 2016 in Uganda (Kabale and Kawanda) and Northern-Tanzania (Maruku and Kitengule) in randomized incomplete blocks with three replications. Summarized data and appropriate parameters were incorporated into the breeder’s equation (R = ih2S). R was positive for mean days to flowering (5 days) and negative for mean number of pods per plant (−9.5 pods) and 100-seed weight (−1.9 g). Diseases (anthracnose, angular leaf spot, and bean common mosaic virus) had positive, undesirable R. Generally, pyramided lines segregated at BC3F9 for disease resistance and yield traits, and thus, superior bean lines should be identified in subsequent generations, such as BC3F11.