Soybean Cyst Nematode Resistance Gene Points to a New Mechanism of Plant Resistance to Pathogens

Soybean cyst nematode (SCN), Heterodera glycines Ichinohe, causes more than a billion dollar in yield losses annually in the United States, it is indeed the most economically important pathogen on soybean. Moreover, virulent populations are overcoming most known resistance sources, therefore, the urgent need to identify, isolate and deploy new genes for resistance to SCN. Genes for resistance to SCN has been identified and mapped to several regions of the soybean genome by both, classical and molecular genetics using a variety of soybean germplasm. The Rhg1 locus on chromosomes 18 and the Rhg4 locus on chromosome 8 were identified by several research teams as two major resistances QTL to SCN. An integrated approach, combining positional cloning with newly developed functional genomics tools in soybean (VIGS, RNAi, Hairy root complementation and TILLING), allowed the isolation and confirmation of a metabolic gene at the Rhg4 locus in resistance to SCN. The discovery is a major breakthrough in the field of plant disease resistance that will impact greatly our understanding of soybean's resistance against SCN and will allow the development of soybean lines with durable resistance to soybean cyst nematode.