Emerging approaches to broaden resistance of soybean to soybean cyst nematode as supported by gene expression studies.

The major pest of soybean (Glycine max) is the soybean cyst nematode (SCN), Heterodera glycines. One population of SCN can evoke a resistant response while a second population can evoke a susceptible response from the same soybean cultivar. Recently, interactions between SCN and soybean roots have been studied using commercially available microarrays to measure both soybean and nematode transcripts. Furthermore, precise dissection of nematode feeding sites (syncytia) using laser capture microdissection (LCM) now allows the study of gene expression specifically in syncytia during a resistant and susceptible reaction. Genes and pathways that are upand down-regulated in roots and syncytia during the interaction of soybean with SCN have been identified. In this Update, we discuss recent research on gene expression during interactions of soybean with SCN and how this information is being used to identify soybean and SCN genes involved in resistance and susceptibility.