THE STRUCTURE AND FUNCTION OF A SOYBEAN BETA-GLUCAN-ELICITOR-BINDING PROTEIN

beta-Glucan elicitor (GE), released from the cell wall of the phytopat hogenic fungus Phytophthora megasperma by soybean glucanases, causes d efense reactions in soybean. A GE-binding protein (GEBP) was purified from the membrane fraction of soybean root cells, and its cDNA was iso lated. Expression of the cDNA clone in tobacco suspension cultured cel ls and in Escherichia coli conferred GE-binding activity to both. An a ntibody against the recombinant protein was found to inhibit the GE bi nding with the soybean cotyledon membrane fraction as well as the resu lting accumulation of phytoalexin. Immunolocalization assays indicated that the GEBPs are located in the plasma membrane of root cells. Thes e results suggest that the cDNA encodes a GE receptor and may mediate the signaling of the elicitor.