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 molecules act as signals and/or receptors in these interactions and how these mechanisms relate to those used in animals and fungi. We are presently working on two different types of systems to try to address this question. In one case we are starting at the molecular level and characterizing a family of receptor protein kinase genes which seem natural candidates for mediating cellular interactions. By analyzing the expression patterns of these genes as well as the phenotypes of transgenic plants bearing altered genes we hope to determine what roles these proteins play in plant development. In the second case we are starting from the organismic level and using genetics to identify genes essential to a whole range of cellular interactions which are required for proper male gametophyte development during reproduction. These interactions involve both recognition of the pollen grain to verify that it is from the correct species and also a transfer of positional information from the female to the male which first allows the pollen tube to determine the polarity of the stigmatic cell on which it has germinated and later provides 'guidance' for the elongating tube to find the ovule.