Plant Genome III Conference Plant Genome III Conference
The ability to produce extensive genotypic information for a population segregating for phenotypic characters has led to the development of extensive linkage maps on which can be placed the locations of Quantitative Trait Loci (QTLs). The difficulty often encountered is presenting, in a concise way, all necessary information concerning the size, position, allelic nature, and gene action for the numerous loci detected. At CIMMYT, we have tried many different methods for presenting this information and are currently utilizing a series of elliptical balloons, whose size is proportional to the effect of the QTL regions. Neighboring these balloons are histograms of genotypic class means, which provide information on the gene action, allele contribution and effect. By overlaying such displays, one can begin to determine the allelic and locus variation detected when the same phenotypic trait is analyzed across environments and germplasm. Results from studies of two traits in three different tropical maize populations across two different environments and several years will be used as an example. Finally, the application of these genomic locations of QTLs - marker assisted selection - requires integrating information regarding the size of each segment, the effect of each segment on the trait of interest, the effect of the segment on yield, and the economic threshold that must be targeted. Together this information defines the optimal segments to be selected.