| The body plans of many metazoans are complex, consisting of multiple axes. In plants, axes formed on the lateral organs define the body plan. For this reason, proper axis formation on the lateral organs is critical because disruptions in axis formation have direct functional consequences that threaten survival of the plants. To form a complex body plan, genes that form axes must be expressed in a specific place to perform a specific function. Any disruptions in genes necessary to form axes will result in reduced fitness for the plants. In spite of its importance, very little is known on a molecular or genetic level about some aspects of the axis formation in plants. I have taken a genetic approach in Arabidopsis to identify and study the genes that are required for axis formation in lateral organs. Axis formation mutations result in the failure to produce the normal lateral organs. Based on these two criteria, I screened and identified two mutants necessary to form axes in lateral organs filamentous flower and revoluta. To gain a foothold from which the molecular mechanisms of axis formation can be elucidated, mutant phenotypes were examined in detail. In addition, genetic interactions between the filamentous flower mutant and the revoluta mutant were discovered. I then cloned these two genes. Cloning revealed that the FILAMENTOUS FLOWER gene encodes a YABBY domain containing putative transcription factor belonging to the YABBY family. The REVOLUTA gene encodes a homeodomain containing putative transcription factor as a member of the HD-ZIP III family. In addition, the expression patterns of these genes were analyzed. The FILAMENTOUS FLOWER gene and some of the family members, YABBY2 and YABBY3, were found to express on the abaxial side of the developing lateral organs. The REVOLUTA gene and the HD-ZIP III family members were found to express on the adaxial side of the developing lateral organs in a unique and overlapping manner. These data contained in this volume provide one of the first footholds from which further research on axis formation in Arabidopsis can progress into the future. |
