Soybean cyst nematode (SCN) is the most economically significant pathogen of soybean in North America. During the infection of host roots, it secretes a diverse array of proteins in its saliva to facilitate a productive infection. Included among these proteins are several different proteases. The goal of my project is to engineer decoy substrates for these proteases that will activate defense responses upon cleavage. Our laboratory has recently shown that the soybean PBS1-1 protein can be engineered to act as such a decoy substrate. Specifically, we have shown that insertion of a cleavage site for the NIa protease from Soybean mosaic virus into GmPBS1-1 enables it to be cleaved by this viral protease, which then activates a programmed cell death response. Our goal is to extend this decoy technology to recognize proteases secreted by SCN during infection. To test whether our decoy approach can be expanded upon, we are developing a soybean root transformation system to determine whether GmPBS1-1 cleavage activates a cell death response in roots. To compliment this approach, we are using protoplast transfection to test candidate decoy proteins for activation of cell death in response to cleavage by SCN proteases. Since other agriculturally significant bacterial, viral, fungal, oomycete, and nematode pathogens are known to secrete proteases, evidence that this technology can function in soybean roots will provide new alternatives to developing resistance to a variety of crop plant pathogens.