Use of RFLP markers in maize as an aid in selection during inbreeding
Zehr, Brent Eugene
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https://hdl.handle.net/2142/21148
Description
Title
Use of RFLP markers in maize as an aid in selection during inbreeding
Author(s)
Zehr, Brent Eugene
Issue Date
1990
Doctoral Committee Chair(s)
Dudley, John W.
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Agronomy
Biology, Biostatistics
Biology, Genetics
Language
eng
Abstract
Molecular markers can be used to detect alleles in donor genetic material for improvement of existing cultivars or hybrids. Restriction fragment length polymorphisms (RFLPs) were used as markers to detect favorable quantitative trait alleles in the maize (Zea mays L.) population BS11(FR)C7 which were not in the hybrid 'FRB73 x FRMo17'. Thirty-four RFLP loci representing 16 chromosome arms were used to determine marker genotypes for 220 (BS11(FR)C7 x FRMo17) F2 individuals. Statistical associations between marker loci and trait expression in F2 x FRB73 progeny were found for grain yield, stalk and root lodging, plant and ear height, maturity, and seven grain yield component traits. Many RFLP loci were associated with expression of multiple traits. RFLP alleles from BS11(FR)C7 were favorable over those from FRMo17 for some loci in all but one trait. Digenic epistasis and environmental effects also appeared to influence marker-trait associations.
If marker loci are to be useful in selection for quantitative traits, a method of weighting information from different loci is needed. Associations between RFLP loci and grain yield were used to develop indices for selection among F2 individuals, and within heterogeneous 54 families derived from F2 selections. Each index involved a matrix of genotypic weights within RFLP loci and a vector of weights among loci. The optimum RFLP index for selection among F2 individuals consisted of a matrix giving equal weight to homozygous and heterozygous favorable RFLP genotypes, and a vector of relative locus weights according to probability of association with grain yield. Indices using subsets of loci were as effective as indices based on fifteen loci for increasing the average frequency of favorable RFLP alleles over all loci in both F2 and S4 selections. Loci with low index weight had greater influence when RFLP selections were within S4 families. These results indicate that relatively few RFLP markers are needed to screen segregating populations for associated loci affecting expression of complex traits. However, RFLP selection at higher levels of inbreeding would require the use of more markers.
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