Phylogeny of Triticeae

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The cereal tribe is a group of grasses that includes three of the most important genera of crop plants: Triticum (wheat), Hordeum (barley), and Secale (rye). Each of these genera has been extensively studied. The tribe also includes 34 other genera, some of which are major forage grasses and many of which have genetic characteristics that would be desirable to introduce into the cereal grasses (e.g. salt tolerance, drought tolerance). These non-crop genera are much less well-known. The transfer of genes through plant breeding is most successful when it involves closely related plants. Therefore, it would be useful to have rigorous models of how wheat, barley, and rye are phylogenetically related to each other and to other members of the tribe. There is a substantial data set available on floral and leaf structure for the cereal tribe, but these data are phylogenetically ambiguous, and there are insufficient characteristics to measure relatedness with confidence. This study will go beyond the floral and leaf data to explore variation with the DNA of these plants. Preliminary data suggest that the chloroplast DNA sequences, or samples of those sequences, can be compared for the members of the tribe and will provide an estimate of which species are most closely related to the major crops. Also, because DNA can be extracted from even very young plants, it will provide an early way to identify plants that could only otherwise be identified at flowering. Both the estimates of relatedness and the DNA markers will provide important tools for plant breeders. An added benefit will be information on the structure of plant DNA in general and how it varies in different plant groups.