Lophopyrum Á. Löve (1980), Thinopyrum Á. Löve (1980), Trichopyrum Á. Löve (1986): one, two or three genera? A study based on the nuclear 5S DNA
2018
Baum, BernardR. | Johnson, DouglasA.
Many species included in the genera Lophopyrum (Á. Löve 1980), Thinopyrum (Á. Löve 1980), and Trichopyrum (Á. Löve 1986) provide germplasm that can be used by breeders to improve commercial wheat cultivars through breeding programs. But various authors have classified them differently, placing them into one, two, three or even more genera. This lack of definition raises the question posed in the title; namely, one, two or three (or more) genera? To answer this question we created a data set of 480 5S nrDNA sequences from 15 species commonly assigned to one or more of these genera by different authors. Based upon the observed variation in DNA sequence of the 5S nrRNA gene mainly within the non-transcribed spacer region, sequences can be summarized into groups or classes of 5S nrDNA that we named unit classes. Unit classes can be assigned to different haplomes within the Triticeae tribe providing a means to study genome composition and species diversity among other ends. These results, where the species were defined on the basis of haplome composition, would then be used to test hypotheses that these species can be placed within a single genus or not. Contingent upon our analyses, we found that haplome composition does not follow the previously proposed taxonomies, based on cytogenetic data, and therefore that all 15 species investigated form one single genus.
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