Isoenzymatic Identification of Quantitative Trait Loci in Crosses of Elite Maize Inbreds

Abstract

This study was conducted to determine if, in crosses among elite inbred lines of maize (Zea mays L.) that are more similar morphologically than the lines used in previous studies, sufficient variation is present to detect quantitative trait loci (QTLs) using marker‐facilitated procedures and to compare elite lines for sources of superior genes. Twenty‐two isozyme loci and one additional locus (P), scored by glume color on the cob, served as genomic markers for detecting QTLs affecting 21 quantitative traits in six F2 populations derived from five elite inbred lines (B73, Mo17, Oh43, Tx303 and T232). A significant effect was found to be associated with at least one chromosomal region for every trait analyzed in the six elite‐cross F2 populations. Despite the greater morphological similarity of the elite lines compared with lines used in previous studies, the number of significant associations detected was similar to results of previous studies, after accounting for differences in population size. Up to 15% of the total phenotypic variation could be explained by factors linked to a single marker locus. The type of gene action at each significant association was determined and the results showed that broad generalizations can be made regarding the gene action for groups of traits. Comparisons made between populations showed that certain areas of the genome consistently affected specific traits: i.e., ear length and grain weight at Amp3 on Chromosome 5 and ear circumference at Glul on Chromosome 10.