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 Title: Identifying Dominant Alleles for Disease Resistance and Stalk Quality in Inbred Maize Author(s): Byrnes, Kenneth Joseph Department / Program: Plant Pathology Discipline: Plant Pathology Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Agriculture, Plant Pathology Abstract: A theory for identifying inbred lines (donor lines) containing dominant favorable alleles not contained in the parents of an F1 cross, was evaluated using both hypothetical and field data. The relative number of the loci containing dominant alleles in each donor line not present in the F1 is described by the statistic $\mu$G$\prime$. Donor lines with the highest $\mu$G$\prime$ values, would be used in a pedigree selection program to improve one or both parents of the F1 cross.Hypothetical data were developed using the assumptions of the theory for a 30 locus trait. Five F1 crosses were evaluated with four donor lines each. The $\mu$G$\prime$ statistic correctly distinguished donors with the highest and lowest values for $\mu$G$\prime$, though some intermediate donors were not properly ranked by $\mu$G$\prime$. When dominance was incomplete, $\mu$G$\prime$ underestimated the value of the dominant loci yet all donors maintained the same ranking as for complete dominance.Fourteen inbred maize (Zea maize L.) lines in a non-reciprocal diallel cross were evaluated for rind strength (RS) as measured by a rind penetrometer, Southern leaf blight (SLB) resistance, and anthracnose stalk rot (ASR) resistance. When five previously chosen F1 crosses were evaluated for $\mu$G$\prime$ values for RS, SLB and ASR the method worked best for the RS data, providing consistent solutions and reasonable results. The donor lines indicated as the best for RS were generally, though not necessarily, among the best lines both per se and for the mean of all possible crosses from the diallel. As the performance of the F1 cross being evaluated decreased, the number of favorable donor lines indicated by $\mu$G$\prime$ and the magnitude of $\mu$G$\prime$ increased. The SLB data would not provide solutions for $\mu$G$\prime$ in all cases. Therefore several different crosses were selected for analysis for SLB. For these crosses, the results were similar to those for RS, except the most negative $\mu$G$\prime$ values indicated the most favorable donor lines. The method was not suited for application to the ASR data since very few lines had ratings which permitted solutions for $\mu$G$\prime$. Issue Date: 1987 Type: Text Description: 70 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987. URI: http://hdl.handle.net/2142/70613 Other Identifier(s): (UMI)AAI8802990 Date Available in IDEALS: 2014-12-15 Date Deposited: 1987
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