INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent npon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margin^ and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9” black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. A Bell & Howell information Company 300 North Zeeb Road. Ann Arbor. Ml 48106-1346 USA 313/761-4700 800/521-0600 GENETIC BASIS OF TOLERANCE IN MAIZE TO MAIZE STREAK VIRUS USING MOLECULAR MARKERS DISSERTATION Presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of The Ohio State University. By Denis Tumwesigye Kyetere B.Sc.(Hons), M.Sc. The Ohio State University 1995 Dissertation Committee Approved by Dr. Richard C. Pratt _____________________________ e ./g * - Adviser Dr. Michael D. McMullen Dr. Steven St. Martin Co-Adviser' Dr. Donald T. Gordon Department of Agronomy UMI Number: 9526050 UMI Microform 9526050 Copyright 1995, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 To my parents, wife Grade and son Emmanuel. ACKNOWLEDGMENTS I wish to express my sincere appreciation Jr. R.C. Pratt, my adviser, Dr. M.D. McMullen, my co-adviser, and members of my advisory committee Drs. S. St. Martin and D.T. Gordon for their consistent support throughout my studies and research. The technical assistance of Mark W. Jones, Brenda S. Schult in the laboratory, Bert Bishop and James Hacker with statistical analyses, and Dr. David Lohnes with the MAPMAKER program is highly acknowledged. I also thank Reiguang Ming with whom we shared the laboratory work load. Without the support of the Director, and the Maize Program team of Namulonge (NAARI), and Mr. W. Page of Natural Resources Institute, U.K., during my field and glasshouse work in Uganda I could not have gone far. Many thanks to Dr. V.O.A. Okoth, who was my in-country adviser in Uganda. I highly appreciate the support of Drs. D.C. Jewell, K.V. Pixley and S.R. Waddington of CIMMYT, Harare, Zimbabwe, and the CIMMYT support staff for providing the most wonderful working environment and happy stay while in Zimbabwe for my research. Without the seed from Dr. J. Brewbaker, I could not have carried out this work. My highest regards to you. I also thank Dr. R. Louie who advised on the glasshouse evaluation method and obtained the original TZi4 accession from the National Germplasm bank in Iowa. I could not have carried out this work without the financial and material support of the following: The Uganda Government, USAID/MFAD, The Rockefeller Foundation, and the World Bank. The support of Mr. M. Erbaugh and Dr. D. Hansen of IPA/OSU is highly appreciated. Thanks to Shelley Whitworth for assisting in putting this dissertation together. Without the support and encouragement of my wife Gracie and our son Emmanuel I could not have reached this stage. A million thanks. VITA October 9, 1956 ...........................Born, Mbarara, Uganda 1979 ............................................. B.Sc.(Hons), Makerere University, Uganda 1979-1983 ................................... Scientific Officer/Maize Agronomy, Kawanda Research Station, Uganda Dec. 81-May 8 2 ........................... Diploma Maize Production, CIMMYT, Mexico June 84-Dec. 8 4 ......................... Diploma Maize Breeding, IARI, New Delhi, India 1984-1993 ................................... Scientific Officer/Maize Breeder, Kawanda and later Namulonge Research Station 1986-1988 ................................... M.Sc. Plant Breeding, University of Wales, U.K. 1993-Present ............................... Senior Research Officer/Maize Breeder, Namulonge (NAARI) Institute FIELDS OF STUDY Major Field: Agronomy v TABLE OF CONTENTS DEDICATION......................................................................................................... ii ACKNOWLEDGMENTS.................................................................................... iii VITA ....................................................................................................................... v LIST OF TABLES.............................................................................................. vii LIST OF FIGURES................................................................................................ix GENERAL INTRODUCTION ................................................................................ 1 CHAPTER PAGE I. GENETIC ANALYSIS OF MAIZE STREAK VIRUS TOLERANCE IN MAIZE USING RESTRICTION FRAGMENT LENGTH POLYMORPHISM..............................................................33 Introduction ................................................................................ 33 Materials and Methods ................................................................37 Results and Discussion ..............................................................59 GENERAL DISCUSSION.................................................................................... 91 LIST OF REFERENCES...................................................................................... 98 APPENDIX 119 LIST OF TABLES TABLE PAGE 1. Mean MSV disease severity values (scale 1-5) of the parents, F1t and RILs in three experiments conducted in two locations .................. 60 2. Mean squares from analysis of MSV scores for disease assessment dates across three locations ..................................................................63 3. Pairwise comparison of location by genotype mean squares from analysis of MSV scores for the four dates across locations .................. 64 4. Response of genotypes to MSV infestation across time and locations .................................................................................................. 67 5. Pearson correlation coefficient of consecutive MSV ratings in each experiment .................................................................................... 68 6. Mean separation of average MSV scores of the parents, F1f and RILs across the four dates ............................................................. 69 7. AUDPC values of parents, F, and RILs of MSV scores of the four dates for each experiment ..............................................................70 8. Chromosomal location of 71 RFLP markers used in this study 71 9. Results from single factor analysis of variance showing loci significantly associated with MSV tolerance, on Chromosome 1, across dates in the three experiments ................................................... 76 10. Results from Knapp and Bridges interval mapping showing probability levels of loci on chromosome 1 associated with MSV to tolerance across dates in the three experiments .....................79 11. Results from MAPMAKER/QTL analysis showing marker intervals on Chromosome 1 detecting significant variation, peak LOD and percent variation (%) var.), for MSV tolerance .....................................84 12. Results from MAPMAKER/QTL analysis showing LOD scores and percent variation (% var.) at marker loci associated on Chromosome 1with MSV tolerance ..................................................... 89 13. MSV data of the RILs for the four ratings of each experiment 120 14. Agronomic traits of RILs taken at Namulonge and Agronomy Farm, Columbus..................................................................................124 viii LIST OF FIGURES FIGURES PAGE 1. Autoradiographs from parental and RIL blots ..........................................46 2. Bioassay method used in the greenhouse and MSV rating scale .... 53 3. MSV symptoms in the glasshouse in Namulonge (Top) and in the field, Harare experiment 2 (Bottom) ....................................................... 62 4. Bar graph showing distribution of RILs and the range where the parents and Ft are fou nd ....................................................................... 65 5. Loci mapped to Chromosome 1 in this stu d y ..........................................74 6. QTL likelihood maps indicating LOD scores, at the fourth rating, for MSV tolerance in the three experiments ...............................87 7. Chromosome 1 showing loci associated with MSV tolerance ...............93 GENERAL INTRODUCTION Occurrence of Maize Streak Maize streak geminivirus (MSV) disease, hereafter referred to as maize streak, was first described by Fuller (1901) as "mealie variegation" in South