TOO MANY MOUTHS (TMM) is a gene which has been shown to regulate cell fate and control cell division in the plant leaf epidermis. TMM encodes a leucine rich repeat-receptor like protein (LRR-RLP) which has putative function as a signal transducing factor in the cell to cell signaling pathway involved in controlling proper spacing of stomata! initials throughout the leaf. This gene has been shown to be widely conserved across species of land plants ranging from bryophytes to angiosperms. Curiously, although this gene is highly conserved, stomata! installation pathways vary considerably across these species. Leaf development in both Arabidopsis and monocot grasses has been well characterized, and contrasting stomata! development pathways have been identified between them. Dioscorea bulbifera is a basal member of the monocot family, but this species forms broad leaves similar to many eudicot species. Stomata! development in this species retains some features characteristic of grass installation pathways such as few to no secondary asymmetric divisions of meristemoids. However, new epidermal cell formation occurs by fill-in between leaf veins, more closely resembling broad leaf eudicot development. A TMM ortholog has been isolated in this species and phylogenetic analysis of the sequence may help to place the signals controlling stomata! proliferation in Dioscorea bulbifera into evolutionary perspective.

<p>A thesis concerning the effects of water deficit on stomatal traits in plants. The relationships between different traits and their influence on overall stomatal anatomy is discussed. Genetic work to investigate molecular regulation of stomatal development is also presented and discussed.</p>

Stomatal development and its regulation by environmental conditions (light, CO2 concentration) and physiological processes in the leaf of higher plants were investigated. The study was based on the assumptions that stomatal development should be regulated by signals coming from both external environment and leaf interior, and that the signal should be transduced from cotyledons to leaves. Transgenerational effect in stomatal development was also studied. Molecular and physiological approaches were applied to reveal the relationship between leaf environment, stomatal development, stomatal function and leaf physiology.