Characterization of mutants affecting the dorsoventral axis and stomatal development of the maize leaf

The aim of this research has been to investigate genes involved in patterning along the dorsoventral (d-v) axis of the maize leaf. The Rolled leaf1 (Rld1) gene was originally identified using semi-dominant mutants that caused partial to complete flipping of the leaf's d-v axis. Here I report a more complete characterization of the mutant phenotype.; A mosaic analysis was used to map the action of Rld1-O to the abaxial epidermis. This result taken with data from dosage analysis experiment, indicating the Rld1 mutants are antimorphs, suggest that wild-type rld1 acts in the abaxial epidermis. Furthermore, the Rld1 mutant phenotype implicates there is trans-epidermal signaling occurring. These results suggest that a signal in a single cell-thick tissue layer is responsible for maintaining polarity of tissue identity across the d-v axis. I present my model for the role of rld1+ in maintenance of d-v polarity.; The most severe allele of Rolled leaf1, Rld1-PB, has a number of phenes that are more fully characterized. I report my interpretation of how a single gene might be responsible for the pleiotropic phenotype. The conclusions I have drawn support the model of dorsoventral outgrowth put forth by Waites and Hudson. This model states that juxtaposition of abaxial and adaxial tissue is required for lamina outgrowth.; In Chapter 3, I report the findings from the dominant maize mutant Intarsial* (Int1*). Int1* mutants have the poorly penetrant phenotype of aberrant stomatal complexes. Investigations into the pattern of divisions leading to mutant stomatal complexes suggest stomatal initials play a role in inducing subsidiary formation from adjacent cell files. Furthermore, double mutant analysis of Int1* with pigmy1 indicates there are separate mechanisms controlling cell division in epidermal ground tissue and the asymmetric divisions of stomatal complexes.