Stomatal Patterning and Differentiation by Synergistic Interactions of Leucine-rich Repeat Receptor Kinases

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The successful adaptation of land plants relied on mechanisms that prevent water loss while allowing efficient gas exchange between plants and the atmosphere. Gas exchange takes place through a stomatal complex, which consists of a pair of guard cells that operate as a turgor-driven valve. Isolation of Arabidopsis mutants with elevated stomatal density and stomatal clustering reveals that stomatal patterning is under genetic regulation. This research project focuses on the cell-cell signaling mechanism regulating stomatal patterning and differentiation. A complete loss of three ERECTA-family receptor-like kinases (RLKs) leads to the generation of high-density stomatal clusters. Further analysis of different erecta-family mutant combinations shows that the three RLKs possess overlapping but distinct functions in two critical steps of stomatal differentiation: (1) the initial decision of protodermal cells to enter proliferative division or asymmetric division to generate stomatal complexes; and (2) the decision to maintain stomatal stem cell activity and prevent terminal differentiation of guard cells. Genetic interactions with a known stomatal patterning mutant, too many mouth (tmm), reveals stoichiometric epistasis and combination-specific neomorphism. These findings suggest that negative regulation of ERECTA-family RLKs by TMM receptor-like protein, is critical for proper stomatal differentiation. The specific aims are:1) to determine the roles of three ERECTA-family receptor kinases during epidermal differentiation.2) to investigate interactions of three receptor kinases with known players of stomatal differentiation.3) to identify novel regulators of stomatal patterning and differentiation by taking advantage of a sensitized mutant background.The proposed research may lead to important agricultural applications, since the ability to manipulate stomatal distribution and patterning may influence photosynthetic efficiency and hence the biomass production of crop plants. A postdoctoral associate, a graduate student and undergraduates, many of whom are women and of diverse ethnic backgrounds, will have excellent opportunities to obtain broad training in plant biology and molecular genetics.