Mapping QTL with Molecular Markers

Application of Molecular Markers to Selection

What Is A Quantitative Trait Locus?

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Application of Molecular Markers to Selection

Once markers have been detected that are associated with QTLs, the logical next step is to perform selection on lines within a population. The obvious method would be to only advance those lines which contain those alleles with a positive effect on the quantitative trait. This type of experiment has not been performed yet, but analogous experiments may give us an indication of what we might expect from such selection experiments.

Stuber et al. (1982; Crop Sci 22:737-740) developed a high-yielding maize population by selecting over ten cycles for increased yield. They next determined the allelic frequencies for eight isozyme loci that had been shown to be associated with yield. These frequencies gave them a base-line from which a new population could be constructed. The new population had essentially the same allelic frequencies as the high yielding population developed by selection. Next the yield and ears/plant were measured in the base population, the high-yielding population developed via selection, and the population constructed based on isozyme frequencies. Data from this replicated experiment grown in several locations suggested that the gain realized by simply pooling on allelic frequencies of the high-yield population was equal to two cycles of selection for yield and one and a half cycles of selection for ears/plant. These results suggest that modest gains may be realized by simply selecting based on the molecular marker genotype.

Copyright © 1998. Phillip McClean