Genetic diversity and differentiation among Korean-Holstein, Hanwoo, and Uganda-Holstein breeds

The aim of this research was to assess genetic diversity of Korean-Holstein, Korean Hanwoo, and Ugandan-Holstein dairy cattle. DNA was extracted from either blood or hair of Korean-Holstein (n=74), Korean-Hanwoo (n=75) and Ugandan-Holstein (N=77) using AccuPrep® PCR purification kit. The DNA samples were amplified by multiplex polymerase chain reaction, using GeneTrackTM Hanwoo genotyping kit and assayed using ABI genetic analyser 3130XL. Number of alleles, expected heterozygosity (He), observed heterozygosity (Ho), and the polymorphism information content (PIC) were estimated from 10 microsatellite loci in the three breeds. In addition, F-statistics for each of the 10 microsatellites in the three cattle breeds were estimated using fstat version 2.9.3.2 computer program. GENETIX (v.4.02) was used to perform factorial correspondence analysis (FCA) from the allele frequencies and multi-locus clustering was done using STRUCTURE analyses. A total of 124 alleles were detected. The number of alleles per locus varied from eight (TGLA126) to 22 (TGLA122), with an overall mean of 12.2. Expected heterozygosity ranged from 0.617 (SPS115) to 0.854 (TGLA53) and averaged 0.761. Observed heterozygosity ranged from 0.6 (SPS115) to 0.859 (TGLA53); and averaged 0.761. The mean PIC was 0.723; and means of the F-statistics FIT, FST and FIS were 0.077, 0.076 and 0.001 respectively. Although FCA revealed clear differentiation of Uganda-Holstein, Korean-Holstein, and Hanwoo, clustering assignments showed genetic admixture between Ugandan dairy cattle (Uganda-Holstein) and Hanwoo. In conclusion, the allelic variation present at the 10 loci was sufficient to categorize these cattle into distinct breed groups. Keywords: dairy cattle, genetic differentiation, F-statistics, heterozygosity, microsatellit

Characterization of Ugandan Isolates of Exserohilum turcicum from Maize

Four representative isolates of Exserohilum turcicum from four major maize growing districts in Uganda were assessed with respect to their cultural variability and pathogenicity towards an isogenic maize series containing the Ht genes for resistance. Two other isolates, one from Zimbabwe and a race 2N isolate from Hawaii, USA, were included for comparative purposes. The isogenic line (H4460), without the Ht gene, developed typical necrotic susceptible lesion type following inoculation with all isolates, whilst H4460Ht1, H4460Ht2 and H4460Ht3 exhibited the resistant chlorotic lesion type. These results indicated that the Ugandan isolates comprised race 0. In vitro studies showed that radial growth rates differed significantly among the isolates, the Ugandan isolates tending to have higher temperature optima than the Zimbabwean one

Characterization of Ugandan isolated of exserohilum turcicumfrom maize

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Characterization of Ugandan Isolates of Exserohilum turcicum from Maize

Four representative isolates of Exserohilum turcicum from four major maize growing districts in Uganda were assessed with respect to their cultural variability and pathogenicity towards an isogenic maize series containing the Ht genes for resistance. Two other isolates, one from Zimbabwe and a race 2N isolate from Hawaii, USA, were included for comparative purposes. The isogenic line (H4460), without the Ht gene, developed typical necrotic susceptible lesion type following inoculation with all isolates, whilst H4460Ht1, H4460Ht2 and H4460Ht3 exhibited the resistant chlorotic lesion type. These results indicated that the Ugandan isolates comprised race 0. In vitro studies showed that radial growth rates differed significantly among the isolates, the Ugandan isolates tending to have higher temperature optima than the Zimbabwean one

Reaction of maize, sorghum and Johnsongrass to Peronosclerospora sorghi

Development of sorghum downy mildew, incited by Peronoscleospora sorghi (Weston and Uppal) C.G. Shaw, on maize, sorghum and Johnson grass was investigated at two locations in Uganda during three seasons (1994 and 1995). More sorghum downy mildew developed on the Johnson grass and sorghum than on the maize at all locations and in all seasons. No significant differences were observed in sporulation of P. soghi on the three hosts. Leaf shredding occurred on the three hosts but was the least on maize. Cross-inoculation with both conidia and oospores was achieved on the three hosts. Since the fungal population formed oospores and sporulated readily on the three hosts, which is typical of the sorghum strain, the disease in Uganda is attributed to the sorghum strain

Germplasm enhancement through cooperative research and breeding using elite tropical and U.S. corn belt maize germplasm

Maize breeding lines with suitable agronomic performance across macroenvironments, and resistance to infection by Cercospora zeae-maydis and Exserohilum turcicum, were selected from a cross between tropical maize inbreds Hi34 and Tzi17. Progenies with acceptable adaptation to Ohio, U.S.A. (41 degrees North latitude) were produced using early generation progeny selection for early maturity, lodging resistance, reduced plant and ear height, and disease resistance. Selected breeding lines were testcrossed with Corn Belt inbreds Mo17 and B73, allowing selection for yield and combining ability, and facilitating cooperative research on host resistance and breeding between U.S. and Ugandan researchers. Preliminary performance evaluations in Ohio, and at a mid-altitude location in Uganda, have revealed testcrosses that are resistant to Exserohilum turcicum and Cercospora zeae-maydis, and are of agronomic quality approaching that of local check varieties. The results of the germplasm enhancement programme demonstrate that the breeding value of this exotic, unadapted germplasm was enhanced by concomitant adaptation and selection of superior traits in a temperate environment, without first crossing to adapted germplasm. Key Words: Exotic germplasm, genetic diversity, germplasm utilisation, introgression, maize breeding Résumé Des lignées de maïs d'amélioration ayant des performances agronomiques favorables à travers des macroenvironnements et avec resistance à l'infection de Cercosporazea-maydis et Exsrohilum turcicum, ont été sélectionnées des croisements entre les familles de maïs tropicales Hi34 et Tzi 17. Des lignées ayant une adaptation acceptable à Ohio, USA (41° latitude Nord) ont été produites en utilisant une sélection de génération de progéniture précoce pour une maturité précoce, une résistance à la verse, une plante de taille réduite, la hauteur d'épi et la résistance aux maladies. Des lignées séléctionnées d'amélioration ont été croisées et crosstestées avec les lignées Corn Belt Mo17 et B13 permettant une sélection pour le rendement et l'aptitude à la combinaison et une recherche collaborative sur la résistance de l'hote et l'amé1ioration entre les chercheurs americains et Ugandais. Les évaluations préliminaries de performance dans la région d'Ohio et dans le région de moyenne altitude d' Uganda, ont montré que les croisements cross tests sont résistants à Exsrohilum turcicum et au Cercosporazea-maydis et sont de bonne qualités agronomiques semblables à celles des variétés locales temoins. Les résultats du programme de renfercement du germoplasme montrent que la valeur d'amélioration du germoplasme éxotique non adapté a été renforcée par une adaptation concommittante et la sélection des traits supérieurs dans un environement temperé sans faire d'abord faire le premier croisement avec le germoplasme adapté. Mots Clés: Gremoplasme éxotique, divesité génétique, utilisation du germoplasme, intogression, amélioration du maïs (African Crop Science Journal, 8(4) 2000: 345-353

Use of IPM in the control of multiple diseases in maize: Strategies for selection of host resistance

Maize (Zea mays) production in sub-Saharan Africa is constantly threatened by the potential outbreak of multiple foliar diseases such as maize streak, northern leaf blight, gray leaf spot, and rust. Improvement of host resistance to these diseases can provide an important component of integrated pest management (IPM). In this paper, conventional and molecular marker-assisted breeding approaches are reviewed and strategies for improvement of host resistance are presented. Pyramiding of quantitative resistance factors using molecular breeding techniques will be facilitated through cooperative research efforts and adoption of appropriate experimental designs. Key Words: Cercospora zeae-maydis, Exserohilum turcicum, gene pyramiding, molecular breeding, resistance breeding, Setosphaeria turcica Résumé La production du maïs (Zea mays) en Afrique au sud du sahara est constamment menacée par l'apparution de multiple infections des feuilles par le streak, le mildiou, le brunissement des feuilles et moisissures. L'augmentation de la résistance a cette maladie peut apporter une importante composante de gestion intégrée de la peste (IPM). Dans cet article, l'approche de croisement assiste des marqueurs conventionels et moléculaires sont présentés et les stratégies d'amélioration de la résistance de la plante hote sont présentées. Les facteurs de résistances pyramidiques et quantitatives utilisant la technique de croisement moléculaires seront facilités à travers les efforts de recherches coopératives et l'adoption d'une approache expérimentale appropriée. Mots Clés: Cercospora zeae-maydis, Exserohilum turcicum, gène pyramidique, croisement moléculaire, croisement résistant, Setosphaeria turcica (Af Crop Sci J 2003 Vol 11 No 3 pp189-198

Disease progress of Peronosclerospora sorghi on some Ugandan maize genotypes

The type and level of disease reaction of Ugandan maize genotypes to Peronosclerospora sorghi was characterized using several variables during the second season of 1994 at two locations, Nazaretti in Mpigi district and Ikulwe in Iganga district. Maize genotypes differed significantly (p 0.05) in susceptibility as determined by the rate of disease increase (r), area under disease progress curve, and disease incidience

Use of IPM in the Control of Multiple Diseases in Maize: Strategies for Selection of Host Resistance

Maize ( Zea mays ) production in sub-Saharan Africa is constantly threatened by the potential outbreak of multiple foliar diseases such as maize streak, northern leaf blight, gray leaf spot, and rust. Improvement of host resistance to these diseases can provide an important component of integrated pest management (IPM). In this paper, conventional and molecular marker-assisted breeding approaches are reviewed and strategies for improvement of host resistance are presented. Pyramiding of quantitative resistance factors using molecular breeding techniques will be facilitated through cooperative research efforts and adoption of appropriate experimental designs.La production du maïs ( Zea mays ) en Afrique au sud du sahara est constamment menacée par l'apparution de multiple infections des feuilles par le streak, le mildiou, le brunissement des feuilles et moisissures. L'augmentation de la résistance a cette maladie peut apporter une importante composante de gestion intégrée de la peste (IPM). Dans cet article, l'approche de croisement assiste des marqueurs conventionels et moléculaires sont présentés et les stratégies d'amélioration de la résistance de la plante hote sont présentées. Les facteurs de résistances pyramidiques et quantitatives utilisant la technique de croisement moléculaires seront facilités à travers les efforts de recherches coopératives et l'adoption d'une approache expérimentale appropriée