Nematodes induce multifaceted changes in plant cellular metabolism and gene expression during the infection process that ultimately gives rise to specialized feeding cells (syncytia) within host plant roots. The underlying molecular mechanisms controlling these processes are largely unknown. We have used laser capture microdissection (LCM) to specifically isolate the contents of nematode-induced feeding cells over a time-course of their development in soybean roots infected with soybean cyst nematode and coupled this with microarray analysis to develop the most comprehensive profile of syncytia-expressed genes to date. We are currently characterizing the function of genes up and down regulated in developing syncytia to assess for direct roles in syncytium induction, development and maintenance. This approach may also prove successful in identifying host targets for engineered resistance. Little is known regarding the molecular mechanisms of soybean resistance to soybean cyst nematode. In soybean resistant to SCN, feeding cell formation is compromised and nematode development is impeded. Using LCM and microarrays, we have also directly compared gene expression profiles in developing syncytia of resistant and susceptible soybean differing at major loci controlling SCN resistance to identify components of the soybean resistance response to SCN. At present, we are characterizing the function of these genes to determine their role in resistance. In addition, we are collaborating with other groups to confirm the identity and function of candidate SCN resistance genes. Our goal is to identify both upstream and downstream components of the resistance gene signaling pathways during the SCN-soybean interaction using functional genomic and reverse genetic approaches.