VAZQUEZ, M. LUCIA*, JEFF J. DOYLE, AND KEVIN C. NIXON. L. H. Bailey Hortorium, 462 Mann Library, Cornell University, Ithaca NY 14853. - Paralogous ITS loci in Mexican red oak species (Quercus section Lobatae) and their implications in phylogeny reconstruction.
In contrast to European and US oak species, there are no molecular
studies addressing the relationships of the diverse Mexican taxa. In
this study we use the ITS-1 and -2 regions to study the phylogeny of
red oaks (Quercus sect. Lobatae), focusing on Mexican
and selected North American species. Previous studies addressing the
phylogeny of oak species using ITS have reported results from only one
putatively orthologous ITS locus. Utilizing additional species, we
found that PCR amplification of the ITS-1 and -2 regions resulted in
products of several sizes for some Mexican oak species. Two of these
products have been characterized: one of them is about 600 bp and the
other is approximately 500 bp long. A comparison of our sequences
with those from previous studies indicates that most of the published
sequences are most similar to our 600 bp copy. Analyses of our
sequences from the 500 bp copy show regions of similarity to the 600
bp copy, however, there is an average divergence of 15% between those
copies. Since multiple ITS loci have been reported for some
angiosperm taxa and unexpected phylogenies have been obtained in some
previous oak studies, the possibility of finding other ITS paralogues
in Quercus should not be ruled out.
Key words: ITS, Mexican species, paralogous, Quercus, red oaks