Tillers are vegetative branches found in grasses, which develop in early stages of plant life. Located at the base of the central stalk, tillers have agronomical importance by increasing seed production with fewer tillers, or providing alternative forms of biofuel with more tillers. As grains have typically decreased tiller number while undergoing domestication, we explored wild and domesticated strains of varying grains by doing a morphological analysis on tiller development. This thesis shows how the decrease of tillers through in domestication cereals shows diversity not only across maize, Sorghum, and Setaria, but also between lines of maize and Setaria species. To do so, we first measured axillary bud growth across these grasses and compared bud initiation, growth, dormancy and outgrowth. While maize inbred B73 demonstrated a tiller dormancy pattern by initiating buds, growing buds and then bud dormancy we measured growth in Sorghum and Setaria to compare and found that although Sorghum patterns dormancy similar to maize, Setaria had more than one way tiller suppression not previously expected. We look further at Setaria buds with a statistical analysis of tiller origin and bud frequency in a wild strain and two domesticated strains of Setaria. Furthermore we performed Scanning Electron Microscopy (SEM) to have a clear understanding of bud initiation or lack of initiation in Setaria italica (B100) comparing it to its wild ancestor Setaria viridis. Because of the diversity in Setaria, we re-visited maize tiller domestication by taking bud measurements, performing SEMs and counting bud frequency on other strains of inbred maize. We found that maize also shows diversity in its patterning of tiller domestication. These results demonstrate that there is diversity in the patterns in which tiller domestication has occurred. This diversity is shown here through differences in tiller bud decisions to initiate or not initiate, or to have axillary buds go dormant post-initiation. Furthermore this variance is shown through differences in bud frequency counts, growth measurements, SEMs, and where tiller branches originate across the grains of maize, Sorghum and Setaria.



College and Department

Life Sciences; Biology



Date Submitted


Document Type



developmental genetics, plant morphology, grain domestication, tillers, axillary meristems, teosinte, maize, Sorghum, Setaria, tb1, gt1, tb1-sh



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Life Sciences Commons