Designing Disease Resistant Plants

Our understanding of plant pathways, signaling, and regulation involved in the plant resistance response to pathogens has greatly expanded over the past twenty years. My laboratory has applied a portion of this knowledge to design soybean with resistance to two different genera of nematodes, the soybean cyst nematode (SCN: Heterodera glycines) and the root-knot nematode (RKN; Meloidogyne incognita). SCN is the major pathogen of soybean, and RKN is a highly destructive pathogen to a wide range of plants, including soybean. We designed over 200 DNA constructs based on data from gene expression studies and from the literature. These DNA constructs overexpress soybean or Arabidopsis genes, or they silence soybean genes or nematode genes. The constructs were transformed into cells at the base of soybean plants to form transgenic roots on composite plants. The transformed plants were inoculated with SCN or RKN to determine if the transgenic roots were more resistant to nematodes. Several constructs reduced SCN cysts and RKN galls more than 60%. It is likely that new approaches, such as these, can provide resistance in plants to an even broader range of pathogens. Plant designs that engineer resistance to a broad range of pathogens will be discussed.