UC San Diego

PNL1 and PNL2 are the closest Arabidopsis relatives of maize pan1. pan1 and the PNL family of 11 genes encode leucine-rich repeat, receptor-like kinases, however none of these putative kinases is predicted to have actual kinase function, due to one or more amino acid substitutions in residues necessary for kinase function. Because PAN1 plays a role in subsidiary cell formation in maize, it is hypothesized that PNL1 and PNL2 are involved in stomatal formation in Arabidopsis. YFP fusions of these proteins are shown here to localize to the epidermis, and PNL2-YFP localizes with brighter points at three-cell junctions and along the points of contact between a subset of epidermal pavement cells and the adjoining guard cell pair. Because no mutant phenotype has been observed for pnl1 and because pnl2 and pnl1; pnl2 double mutants have no reproducible phenotype, a PNL2 truncated overexpression construct with the inactive kinase domain replaced by YFP was produced to be evaluated as a dominant negative mutation. To date, only a preliminary analysis of plants carrying this construct has been performed, showing no stomatal phenotype, but the construct has a similar localization pattern to that of PNL2-YFP. An analysis has also been performed on genotyping data from the isolation of the pnl1; pnl2 double mutants showing that double mutants are underrepresented in a segregating population, suggesting that there are possible transmission problems that occur in double mutant pollen