In addition to permitting comparisons of sequence homology across species and genera, this will permit our laboratories to determine whether QTL loci, like their cognate RFLP markers, tend to map to homoeologous locations across The Talbert lab has focused its efforts on molecular genetic analysis of wheat. Cultivated wheat and its relatives have evolved through divergence at the diploid level, followed by evolutionary convergence via polyploidy. This type of reticulate evolution has led to immense variability in the wheat tribe, but also to difficulties in evolutionary analysis. Most evolutionary inferences in the wheat tribe have come from studies of chromosome pairing in hybrids. Thus, a concern regards whether or not germplasm groups can be adequately sampled.
Molecular approaches have the advantage of allowing a larger number of individuals to be assayed.
We are developing molecular markers to test the hypothesis that crossing among polyploid wheats with a common genome is an important evolutionary process. Thus, our focus is on developing multiple PCR markers for low copy sequences on each of the chromosome arms of wheat and using these to compare allopatric and sympatric accessions of polyploid wild wheats. Our basic hypothesis is that sympatric accessions will share more sequences than allopatric accessions if introgression is a common event. Preliminary results suggest that introgression among the polyploid wild wheats may be less common than previously supposed. This latter aspect includes evaluating alternative hypotheses that invoke over-water dispersal from the paleotropics to the neotropics, migration from South America since the formation of the Panamanian Isthmus, and migration from Eurasia prior to the dissolution of the North Atlantic land bridge.