MOLECULAR-GENETICS OF CELL-INTERACTIONS IN ARABIDOPSIS

Many events in plant development are regulated by the interactions of neighboring cells. We are interested in determining what sorts of mole cules act as signals and/or receptors in these interactions and how th ese mechanisms relate to those used in animals and fungi. We are prese ntly working on two different types of systems to try to address this question. In one case we are starting at the molecular level and chara cterizing a family of receptor protein kinase genes which seem natural candidates for mediating cellular interactions. By analyzing the expr ession patterns of these genes as well as the phenotypes of transgenic plants bearing altered genes we hope to determine what roles these pr oteins play in plant development. In the second case we are starting f rom the organismic level and using genetics to identify genes essentia l to a whole range of cellular interactions which are required for pro per male gametophyte development during reproduction. These interactio ns involve both recognition of the pollen grain to verify that it is f rom the correct species and also a transfer of positional information from the female to the male which first allows the pollen tube to dete rmine the polarity of the stigmatic cell on which it has germinated an d later provides 'guidance' for the elongating tube to find the ovule.