The Moral acceptability of genetically modified foods (gmo’s)

9TH Annual ethics conference. Theme : Bioethics medical, legal, environmental and cultural aspects in healthcare ethics at STRATHMORE UNIVERSITY, 25-26 OCTOBER 2012.There is belief that the use of biotechnologies in combination with conventional plant breeding, can contribute to the food security of Africa. Some of these potential benefits of genetically modified biotech crops include tolerance to salinity, resistance to pests, and enhanced nutritional value. Nutritionally enhanced crops are important in developing countries to fight malnutrition and its related diseases. On the other hand the advent of biotech crops has been met with skepticism by different sectors of the public. People want to know whether these crops are safe, cheaper and more nutritious. However, informed decisions about their use have been left to individual countries. In Kenya, Genetically modified maize has been imported into the country to meet the current shortfall in the maize crop. This has been met with public outcry. The purpose of this study was to examine the moral acceptability of genetically modified foods using the Aristotelian understanding of Ethics. This is method looks at the elements involved in any free human act and analyses the object, intention and circumstances surrounding such an act. In the case of genetic modification this is to ascertain whether such an action enhance the nature of man and his common good. The approach used was to make use of secondary data source in order to understand the ethicalness of modifying GM foods based on Aristotelian Ethics Results were analysed based on different scenarios labeled A-H. The moral object analysed in all the scenarios were the GM foods inserted with genes from plants,animals,bacteria or viruses so as to confer advantages to the modified crops such as drought, disease and pest resistance. The intentions were varied. For instance the intention of scientists would be to engineer food crops so as to acquire food security. This can be a morally good action since it enhances the human dignity. The circumstances surrounding such an action could be that some of these genes might be harmful to human beings and the environment because most times these genes are coming from non plants. The moral value of such an action is bad because it will affect human health negatively and hence go against the human nature. The implications of this study indicate that the human aspect in Gm foods must be taken into consideration because it is the human person who adds to any aspect the ethical or moral dimension. Also Universities like Strathmore University, which has a strong background in Ethics should team up with other research institutes engaged in the production of GM products and ensure that these products are not only economically and technologically sound but also morally sound.There is belief that the use of biotechnologies in combination with conventional plant breeding, can contribute to the food security of Africa. Some of these potential benefits of genetically modified biotech crops include tolerance to salinity, resistance to pests, and enhanced nutritional value. Nutritionally enhanced crops are important in developing countries to fight malnutrition and its related diseases. On the other hand the advent of biotech crops has been met with skepticism by different sectors of the public. People want to know whether these crops are safe, cheaper and more nutritious. However, informed decisions about their use have been left to individual countries. In Kenya, Genetically modified maize has been imported into the country to meet the current shortfall in the maize crop. This has been met with public outcry. The purpose of this study was to examine the moral acceptability of genetically modified foods using the Aristotelian understanding of Ethics. This is method looks at the elements involved in any free human act and analyses the object, intention and circumstances surrounding such an act. In the case of genetic modification this is to ascertain whether such an action enhance the nature of man and his common good. The approach used was to make use of secondary data source in order to understand the ethicalness of modifying GM foods based on Aristotelian Ethics Results were analysed based on different scenarios labeled A-H. The moral object analysed in all the scenarios were the GM foods inserted with genes from plants,animals,bacteria or viruses so as to confer advantages to the modified crops such as drought, disease and pest resistance. The intentions were varied. For instance the intention of scientists would be to engineer food crops so as to acquire food security. This can be a morally good action since it enhances the human dignity. The circumstances surrounding such an action could be that some of these genes might be harmful to human beings and the environment because most times these genes are coming from non plants. The moral value of such an action is bad because it will affect human health negatively and hence go against the human nature. The implications of this study indicate that the human aspect in Gm foods must be taken into consideration because it is the human person who adds to any aspect the ethical or moral dimension. Also Universities like Strathmore University, which has a strong background in Ethics should team up with other research institutes engaged in the production of GM products and ensure that these products are not only economically and technologically sound but also morally sound

An examination into the ethical acceptability of genetically modified foods in Kenya principled on Aristotelian Ethics

Conference paperEthics is a branch of Philosophy which studies free human acts from the point of view of their moral value (goodness or badness) in relation with the last end of man( Debeljuh,2006). Ethics is able to ascertain what man‘s final goal is and to determine the type of behaviour that will lead him to that final goal which ultimately should give him happiness. In this paper I would like to examine the ethical acceptability of GM foods in Kenya using the Aristotelian understanding of ethics. For Aristotle, ethics is based on achieving the chief good for man which he called eudaimonia (‗happiness‘). He said that eudaimonia is something that is ―final and self sufficient and is the end that our human action tends toward. Aristotle discovered that this happiness if found by man exercising his rational nature which gives him the capacity to direct himself to the good in every action. Looking at the GM foods from this point of view, the paper will try to examine if GM foods enhance the nature of man by taking into consideration his rational nature as well as promoting the common good of man. Anything that goes against his nature would be considered morally unacceptable. Aristotle defines the common good as the perfect goal of the state which requires an admission of the individual's basic right in society. This basic right means the right of everyone to the opportunity to freely shape his life by responsible action, in pursuit of virtue and in accordance with the natural moral law.Ethics is a branch of Philosophy which studies free human acts from the point of view of their moral value (goodness or badness) in relation with the last end of man( Debeljuh,2006). Ethics is able to ascertain what man‘s final goal is and to determine the type of behaviour that will lead him to that final goal which ultimately should give him happiness. In th is paper I would like to examine the ethical acceptability of GM foods in Kenya using the Aristotelian understanding of e thics. For Aristotle , e thics is based on achieving the chief good for man which he called eudaimonia ( ̳happiness‘). He said that eudaim onia is something that is ―final and self sufficient and is the end that our human action tends toward. Aristotle discovered that this happiness if found by man exercising his rational nature which gives him the capacity to direct himself to the good in ev ery action. Looking at the GM foods from this point of view, the paper will try to examine if GM foods enhance the nature of man by taking into consideration his rational nature as well as promoting the common good of man. Anything that goes against his na ture would be considered morally unacceptable. Aristotle defines the common good as the perfect goal of the state which requires an admission of the indiv idual's basic right in society. This basic right means the right of everyone to the opportunity to fre ely shape his life by responsible action, in pursuit of virtue and in accordance with the natural moral law

Enhancing the careers of East African women scientists

Profiles of the G&D-Rockefeller fellowship winners.A Three-Year Program supported by The Rockefeller Foundation and implemented by the Gender and Diversity Program (G&D) of the Consultative Group on International Agricultural Research (CGIAR)A Three-Year Program supported by The Rockefeller Foundation and implemented by the Gender and Diversity Program (G&D) of the Consultative Group on International Agricultural Research (CGIAR

Analysis of diversity among East African sweet potato cultivars (ipomoea batatas) using morphological and simple sequence repeats dna markers

A Thesis submitted in partial fulfillment of the requirements for the degree of master of science in molecular biology of Makerere University, Kampala. Full thesis.East Africa is considered to be a secondary centre of origin of sweet potato and it is suspected that the wide morphological variation observed indicates wide genetic diversity in the region. To conserve and utilize the germplasm, it is important that proper assessment of the diversity of the East African sweet potato germplasm be made.Identification by molecular technologies is more commonly used over morphological characters since the latter can be influenced by environmental factors. In this study, we used molecular and morphological markers to study the genetic diversity of the germplasm in the region. Collections of cultivars were made from selected locations of Uganda, Kenya and Tanzania and subsequently established in pots in a screen house at Makerere University. A total of 266 cultivars were collected. After 3 weeks, the cultivars were screened for morphological characters using the CIP Research Guide. Cluster analysis was done using UPGMA in Treecon (Version 1.3). Based on morphological grouping, 57 cultivars, which were morphologically diverse, were randomly selected for DNA extraction and further analysis was done. Cluster analysis revealed only two major groupings (A & B) of sweet potatoes with very low bootstrap support of 0-54 %. The key distinguishing morphological markers were triangular leaf outline and a cordate shaped leaf outline for group A & B respectively. In addition, there were no geographical distinct morphological types identified. No population structure was detected. However, within each country, a high variation was observed (97.65%), suggesting that a wide range of cultivars is being grown in each country. Microsatellite (SSR) reactions were performed using four SSR primer combinations. The polymerase chain reaction (PCR) products were resolved using a high resolution metaphor agarose gel electrophoresis. Genetic distance data matrices were subjected to Unweighted pair-group method of arithmetic averages (UPGMA) clustering using TREECON phylogenetic program Version 1.3 b. Two major sub-clusters were found by UPGMA at a bootstrap value of 54 %. Low bootstrap values (0-55 %) indicate absence of clusters and close genetic relationships among the cultivars. The majority of cultivars were in the range of 0.1-0.3 Nei's genetic distance from each other, which also shows close genetic relatedness. The clustering of sweet potato cultivars based on SSR markers showed that cultivars from Kenya, Uganda and Tanzania were grouping in group A. In sub-cluster B the cultivars were from Uganda and they seemed to form a unique group. However the Tanzanian cultivars seem to cluster closely together in various sub-clusters. Analysis of Molecular Variance (AMOVA) indicated that there is statistically measurable divergence between the sweet potato of Uganda-Kenya and the other East-African country, Tanzania with detectable difference between the cultivars of the three sources. The largest source of diversity comes from within-population variation, which accounts for 88.91 % of the total variance. The data from AMOVA analysis also indicated an F st value >0.05 which seems to suggest great genetic differentiation amongst the cultivars in the East African region and hence presence of a population structure. The gene flow values > 1 shows that there is high genetic drift amongst the cultivars in this region. In this study, the morphological analysis of sweet potato landraces indicated that there was not much variation in the East African sweet potato. However the investigation at genome level using PCR-based SSR markers was able to identify significant variation amongst the landraces and existence of a population structure. The major results in this study indicate that SSR markers are appropriate for the genotyping and revealing genetic relationship of East African sweetpotato cultivars. In addition, morphological characterisation should be complemented with DNA –based characterisation using SSR markers to reveal genetic diversity of East African sweet potato cultivars.East Africa is considered to be a secondary centre of origin of sweet potato and it is suspected that the wide morphological variation observed indicates wide genetic diversity in the region. To conserve and utilize the germplasm, it is important that proper assessment of the diversity of the East African sweet potato germplasm be made.Identification by molecular technologies is more commonly used over morphological characters since the latter can be influenced by environmental factors. In this study, we used molecular and morphological markers to study the genetic diversity of the germplasm in the region. Collections of cultivars were made from selected locations of Uganda, Kenya and Tanzania and subsequently established in pots in a screen house at Makerere University. A total of 266 cultivars were collected. After 3 weeks, the cultivars were screened for morphological characters using the CIP Research Guide. Cluster analysis was done using UPGMA in Treecon (Version 1.3). Based on morphological grouping, 57 cultivars, which were morphologically diverse, were randomly selected for DNA extraction and further analysis was done. Cluster analysis revealed only two major groupings (A & B) of sweet potatoes with very low bootstrap support of 0-54 %. The key distinguishing morphological markers were triangular leaf outline and a cordate shaped leaf outline for group A & B respectively. In addition, there were no geographical distinct morphological types identified. No population structure was detected. However, within each country, a high variation was observed (97.65%), suggesting that a wide range of cultivars is being grown in each country. Microsatellite (SSR) reactions were performed using four SSR primer combinations. The polymerase chain reaction (PCR) products were resolved using a high resolution metaphor agarose gel electrophoresis. Genetic distance data matrices were subjected to Unweighted pair-group method of arithmetic averages (UPGMA) clustering using TREECON phylogenetic program Version 1.3 b. Two major sub-clusters were found by UPGMA at a bootstrap value of 54 %. Low bootstrap values (0-55 %) indicate absence of clusters and close genetic relationships among the cultivars. The majority of cultivars were in the range of 0.1-0.3 Nei's genetic distance from each other, which also shows close genetic relatedness. The clustering of sweet potato cultivars based on SSR markers showed that cultivars from Kenya, Uganda and Tanzania were grouping in group A. In sub-cluster B the cultivars were from Uganda and they seemed to form a unique group. However the Tanzanian cultivars seem to cluster closely together in various sub-clusters. Analysis of Molecular Variance (AMOVA) indicated that there is statistically measurable divergence between the sweet potato of Uganda-Kenya and the other East-African country, Tanzania with detectable difference between the cultivars of the three sources. The largest source of diversity comes from within-population variation, which accounts for 88.91 % of the total variance. The data from AMOVA analysis also indicated an F st value >0.05 which seems to suggest great genetic differentiation amongst the cultivars in the East African region and hence presence of a population structure. The gene flow values > 1 shows that there is high genetic drift amongst the cultivars in this region. In this study, the morphological analysis of sweet potato landraces indicated that there was not much variation in the East African sweet potato. However the investigation at genome level using PCR-based SSR markers was able to identify significant variation amongst the landraces and existence of a population structure. The major results in this study indicate that SSR markers are appropriate for the genotyping and revealing genetic relationship of East African sweetpotato cultivars. In addition, morphological characterisation should be complemented with DNA –based characterisation using SSR markers to reveal genetic diversity of East African sweet potato cultivars

Ultrastructure of the infection of sorghum bicolor and zea mays by pythium species

Research PaperThe practice of cultivating mixed crops is common in Tropical Africa and elsewhere especially in areas of high population density. The practice of mixed cropping can promote disease spread especially in multi-host pathosystems. Pythium is a soil borne oomycete with a wide host range affecting both cereal and legumes. In this paper we examine pathogenesis by Pythium species in maize and sorghum, crops commonly included as intercrops in south western Uganda. In this study, both electron and light microscopy were used to study infection process using bean derived Pythium species-Pythium ultimum (MS 61) and Pythium irregulare (DFD 47) on beans, maize and sorghum. Electron microscopy revealed that on maize P.irregulare hyphae remained extracellular while P. ultimum hyphae in epidermis underwent necrosis after 9 days. In sorghum on the contrary, P. ultimum and P. irregulare extensively colonised both the epidermis and endodermis. In this study, P. ultimum also had two types of hyphae which mediated infection thus making it more virulent than P. irregulare. The results of this study confirm that Pythium spp. are pathogenic on sorghum and therefore the role of sorghum in Pythium inoculum build-up in bean fields cannot be precluded.The practice of cultivating mixed crops is common in Tropical Africa and elsewhere especially in areas of high population density. The practice of mixed cropping can promote disease spread especially in multi-host pathosystems. Pythium is a soil borne oomycete with a wide host range affecting both cereal and legumes. In this paper we examine pathogenesis by Pythium species in maize and sorghum, crops commonly included as intercrops in south western Uganda. In this study, both electron and light microscopy were used to study infection process using bean derived Pythium species-Pythium ultimum (MS 61) and Pythium irregulare (DFD 47) on beans, maize and sorghum. Electron microscopy revealed that on maize P.irregulare hyphae remained extracellular while P. ultimum hyphae in epidermis underwent necrosis after 9 days. In sorghum on the contrary, P. ultimum and P. irregulare extensively colonised both the epidermis and endodermis. In this study, P. ultimum also had two types of hyphae which mediated infection thus making it more virulent than P. irregulare. The results of this study confirm that Pythium spp. are pathogenic on sorghum and therefore the role of sorghum in Pythium inoculum build-up in bean fields cannot be precluded

The Role of mixed cropping systems on bean root rot epidemics in south western Uganda

Research PaperIn south western Uganda, beans are largely grown as intercrops with sorghum, maize, sweet potato and potato . Continuous cropping of beans, has increased bean root rot epidemics. Since some of the root rot causing organisms are known to affect other crops, there was need to investigate the role they may be playing in the current root rot epidemics. Surveys were carried out in Kabale district in order to establish the incidence of root rot on other crops grown in association with beans. Plant samples for isolation of Pythium, the main causative agent of root rot were also collected. Results indicated that potato had a high root rot incidence while maize had a low root rot incidence. Also, sorghum and peas had root rot symptoms. Out of the 142 Pythium isolates collected, 21 different Pythium species were identified by ITS-DNA sequencing. Fifteen new Pythium species not previously identified in the region were found. This study finds evidence that diverse crop species associated with beans may be playing a role in bean root rot epidemics.In south western Uganda, beans are largely grown as intercrops with sorghum, maize, sweet potato and potato . Continuous cropping of beans, has increased bean root rot epidemics. Since some of the root rot causing organisms are known to affect other crops, there was need to investigate the role they may be playing in the current root rot epidemics. Surveys were carried out in Kabale district in order to establish the incidence of root rot on other crops grown in association with beans. Plant samples for isolation of Pythium, the main causative agent of root rot were also collected. Results indicated that potato had a high root rot incidence while maize had a low root rot incidence. Also, sorghum and peas had root rot symptoms. Out of the 142 Pythium isolates collected, 21 different Pythium species were identified by ITS-DNA sequencing. Fifteen new Pythium species not previously identified in the region were found. This study finds evidence that diverse crop species associated with beans may be playing a role in bean root rot epidemics

Pathogenicity of pythium species on hosts associated with bean-based cropping system in south western Uganda

Research PaperA pathosystem is a subsystem of an ecosystem and is characterised by the phenomenon of parasitism. The bean-Pythium pathosystem consists of the host (bean), the pathogen (Pythium) and their host-pathogen relation. Of interest is how the pathogen causes pathogenicity on other crops and beans. To investigate this, screen house experiments were set up to test the pathogenicity of Pythium species derived from bean and other crops grown in association with beans. Pathogenicity was tested on maize (Zea mays), millet (Eleusine corcana), sorghum (Sorghum bicolor), peas (Pisum satium), susceptible bean variety (CAL 96) and resistant bean variety (RWR 719). The results indicated that distinct symptoms were observed in the roots and shoots of test crop species which are characteristic of Pythium infection. For instance peas had brownish watery stems and roots Also bean-derived pathogenic Pythium spp. were found to be more virulent than Pythium spp. derived from other crop species.Sorghum and peas had the highest disease scores upon infection by Pythium spp. We can conclude that there is cross pathogenicity among Pythium spp. especially affecting sorghum and peas. This phenomenon may account for the current root rot epiphytotics in south western Uganda and other similar agroecologies. An integrated disease management strategy that will deploy multi-non hosts to Pythium root rot is recommended.A pathosystem is a subsystem of an ecosystem and is characterised by the phenomenon of parasitism. The bean-Pythium pathosystem consists of the host (bean), the pathogen (Pythium) and their host-pathogen relation. Of interest is how the pathogen causes pathogenicity on other crops and beans. To investigate this, screen house experiments were set up to test the pathogenicity of Pythium species derived from bean and other crops grown in association with beans. Pathogenicity was tested on maize (Zea mays), millet (Eleusine corcana), sorghum (Sorghum bicolor), peas (Pisum satium), susceptible bean variety (CAL 96) and resistant bean variety (RWR 719). The results indicated that distinct symptoms were observed in the roots and shoots of test crop species which are characteristic of Pythium infection. For instance peas had brownish watery stems and roots Also bean-derived pathogenic Pythium spp. were found to be more virulent than Pythium spp. derived from other crop species.Sorghum and peas had the highest disease scores upon infection by Pythium spp. We can conclude that there is cross pathogenicity among Pythium spp. especially affecting sorghum and peas. This phenomenon may account for the current root rot epiphytotics in south western Uganda and other similar agroecologies. An integrated disease management strategy that will deploy multi-non hosts to Pythium root rot is recommended

Influence of farming systems and crop host varieties on pythium root rot epidemics in a highland agroecology of South Western Uganda

A Thesis submitted to the school of graduate studies in fulfillment for the requirements of the award of a Doctor of Philosophy of Makerere University. Full thesis.The bean crop is one of East African’s principal crops. It is grown primarily by small scale farmers who are mainly women, for home consumption and any excess is sold (Wortmann et al., 1998). The increase in severity and incidence of bean root rots has been associated with recent changes in farming systems, especially under high demographic pressure and decline in soil fertility (Rusuku et al., 1997). The importance of root rots in causing bean crop failures was recognised in Rwanda in 1988 and subsequently in Burundi, the Democratic Republic of Congo, Kenya and Uganda (CIAT,1992; Otsyula et al., 1998; Opio, 1998). Although bean root rot is caused by a number of soil borne pathogens depending on environmental conditions, Pythium spp. are the fungal pathogens most frequently associated with severe epidemics in eastern Africa (Rusuku etal., 1997).In south western Uganda, root rot is caused by a number of pathogens, which occur either singly or as complexes. These include Fusarium spp, Rhizoctonia solanii and Pythium spp. with the latter being the major pathogen (Opio, 1998). Studies on root rots have indicated that continuous cropping of beans, a common practice in eastern Africa exacerbates the problem (Rusuku et al., 1997). Due to population and land pressure in these high productive areas, beans are commonly cultivated with other crop plants. Yet Pythium species attack a number of crop species and other plants (Ampaire, 2003). There is a need therefore to investigate whether root rots occur in other crops in the bean based system and in addition, to characterise Pythium species responsible for these root rots.This information will provide evidence on whether novel Pythium species are implicated in the bean root rot epidemics and whether other crop species are influencing the root rot epidemics in south western Uganda. In the first part of the study, surveys were done in Kabale district so as to characterise root rots of non bean crops grown in association with beans. Molecular characteristation using the ITS-DNA sequences was also carried out on these crop species. Non bean crops in bean pathosystem of south western Uganda were found to be affected by root rots. The crops included Irish potato, sorghum and peas. This implys that beans are not the only crops in the pathosystem to be attacked by the disease. Using ITS-DNA sequences, 142 Pythium species were characterised from non bean crops. The most abundant of the Pythium species on these crops was Pythium ultimum. Also, a complex of pathogens were isolated from non bean crops and these included Pythium, Fusarium species and Veriticillium. The implication of this is that there is a host-pathogen selectivity as some Pythium species were found to affect leguminous crops and other solanaceous crops. In the second part of the study cross pathogenicity was done in the screen house. Bean derived and non bean derived Pythium species were use to test their pathogenicity on resistant and susceptible bean variety, cereals and legumes. Sorghum and peas were found to be susceptible to both bean derived and non bean derived Pythium species. Maize and millet were found to be resistant. These resistant crops may be able to produce biochemical reactions in their cells and tissues which are toxic to pathogen. Cereal crops having fibrous roots could counteract infection better than legumes which have tap roots. Hence cereals had a higher root mass compared to legumes. Symptoms charactersistic of Pythium infection such as wilting, stunting and chlorosis were observed. This arises due to Pythium species reducing water uptake to leaves therefore resulting in wilting.The third part of the study involved the use of light and electron microscopy techniques to investigate the pattern of infection of bean pathogenic Pythium species on sorghum and maize. Sorghum was found to be susceptible to bean pathogenic Pythium species.The infection pattern in sorghum was similar to susceptible bean variety (CAL 96).Maize was resistant to bean pathogenic Pythium species and the infection pattern was similar to resistant bean variety (AND 1062). This confirms that sorghum is an alternative host of Pythium. Pythium infection in crop species was mediated by the formation of appressoria-bearing hyphae. In the study, there was also evidence of hemibiotrophic infection found with Pythium ultimum possessing two kinds of hyphae. This suggests that virulence of P.ultimum is affected by these two hyphae. This study has therefore found evidence that th cultivation of beans in mixed cropping systems with non bean crop species may partly contribute to bean root rot epidemics.Sorghum and peas which are popular intercrops were found to be alternative hosts of pathogenic Pythium species implying that they contribute to pathogen inoculum load in the soil hence increased disease outbreaks. 2. Maize and millet were found to be resistant to Pythium species . This implies that these crops are poor hosts of pathogenic Pythium species therefore these crops could be included in bean rotations in south western Uganda so as to reduce Pythium soil inoculum load. 3. Differences in pathogenicity were found to occur within the pathogenic Pythium species.This phenomenon suggests the possibility for directional selection leading to increase in species or even pathotype abundances among Pythium pathogenic species. 4. Of the Pythium species isolated from bean and non bean hosts some were pathogenic others were not. Given the mulit- pathogenicity capacity of this genus, evolution of novel Pythium strains/ pathogens on both beans and non-bean hosts cannot be precluded. 5. Resistant bean varieties ( RWR 719 & AND1062) and non bean crops such as maize had similar disease reaction to bean pathogenic Pythium infection ..The bean crop is one of East African’s principal crops. It is grown primarily by small scale farmers who are mainly women, for home consumption and any excess is sold (Wortmann et al., 1998). The increase in severity and incidence of bean root rots has been associated with recent changes in farming systems, especially under high demographic pressure and decline in soil fertility (Rusuku et al., 1997). The importance of root rots in causing bean crop failures was recognised in Rwanda in 1988 and subsequently in Burundi, the Democratic Republic of Congo, Kenya and Uganda (CIAT,1992; Otsyula et al., 1998; Opio, 1998). Although bean root rot is caused by a number of soil borne pathogens depending on environmental conditions, Pythium spp. are the fungal pathogens most frequently associated with severe epidemics in eastern Africa (Rusuku etal., 1997).In south western Uganda, root rot is caused by a number of pathogens, which occur either singly or as complexes. These include Fusarium spp, Rhizoctonia solanii and Pythium spp. with the latter being the major pathogen (Opio, 1998). Studies on root rots have indicated that continuous cropping of beans, a common practice in eastern Africa exacerbates the problem (Rusuku et al., 1997). Due to population and land pressure in these high productive areas, beans are commonly cultivated with other crop plants. Yet Pythium species attack a number of crop species and other plants (Ampaire, 2003). There is a need therefore to investigate whether root rots occur in other crops in the bean based system and in addition, to characterise Pythium species responsible for these root rots.This information will provide evidence on whether novel Pythium species are implicated in the bean root rot epidemics and whether other crop species are influencing the root rot epidemics in south western Uganda. In the first part of the study, surveys were done in Kabale district so as to characterise root rots of non bean crops grown in association with beans. Molecular characteristation using the ITS-DNA sequences was also carried out on these crop species. Non bean crops in bean pathosystem of south western Uganda were found to be affected by root rots. The crops included Irish potato, sorghum and peas. This implys that beans are not the only crops in the pathosystem to be attacked by the disease. Using ITS-DNA sequences, 142 Pythium species were characterised from non bean crops. The most abundant of the Pythium species on these crops was Pythium ultimum. Also, a complex of pathogens were isolated from non bean crops and these included Pythium, Fusarium species and Veriticillium. The implication of this is that there is a host-pathogen selectivity as some Pythium species were found to affect leguminous crops and other solanaceous crops. In the second part of the study cross pathogenicity was done in the screen house. Bean derived and non bean derived Pythium species were use to test their pathogenicity on resistant and susceptible bean variety, cereals and legumes. Sorghum and peas were found to be susceptible to both bean derived and non bean derived Pythium species. Maize and millet were found to be resistant. These resistant crops may be able to produce biochemical reactions in their cells and tissues which are toxic to pathogen. Cereal crops having fibrous roots could counteract infection better than legumes which have tap roots. Hence cereals had a higher root mass compared to legumes. Symptoms charactersistic of Pythium infection such as wilting, stunting and chlorosis were observed. This arises due to Pythium species reducing water uptake to leaves therefore resulting in wilting.The third part of the study involved the use of light and electron microscopy techniques to investigate the pattern of infection of bean pathogenic Pythium species on sorghum and maize. Sorghum was found to be susceptible to bean pathogenic Pythium species.The infection pattern in sorghum was similar to susceptible bean variety (CAL 96).Maize was resistant to bean pathogenic Pythium species and the infection pattern was similar to resistant bean variety (AND 1062). This confirms that sorghum is an alternative host of Pythium. Pythium infection in crop species was mediated by the formation of appressoria-bearing hyphae. In the study, there was also evidence of hemibiotrophic infection found with Pythium ultimum possessing two kinds of hyphae. This suggests that virulence of P.ultimum is affected by these two hyphae. This study has therefore found evidence that th cultivation of beans in mixed cropping systems with non bean crop species may partly contribute to bean root rot epidemics.Sorghum and peas which are popular intercrops were found to be alternative hosts of pathogenic Pythium species implying that they contribute to pathogen inoculum load in the soil hence increased disease outbreaks. 2. Maize and millet were found to be resistant to Pythium species . This implies that these crops are poor hosts of pathogenic Pythium species therefore these crops could be included in bean rotations in south western Uganda so as to reduce Pythium soil inoculum load. 3. Differences in pathogenicity were found to occur within the pathogenic Pythium species.This phenomenon suggests the possibility for directional selection leading to increase in species or even pathotype abundances among Pythium pathogenic species. 4. Of the Pythium species isolated from bean and non bean hosts some were pathogenic others were not. Given the mulit- pathogenicity capacity of this genus, evolution of novel Pythium strains/ pathogens on both beans and non-bean hosts cannot be precluded. 5. Resistant bean varieties ( RWR 719 & AND1062) and non bean crops such as maize had similar disease reaction to bean pathogenic Pythium infection .