Updated December 10, 2019:
Soybean cyst (SCN) and root-knot (RKN) nematodes are the most yield-limiting pests of soybean in the USA. SCN is by far the number one yield-limiting pest and RKN is a major problem, particularly in the sandy or sandy loam soils in the southern USA. Although cultural practices in soybean production fields can help reduce some of the yield loss from nematode damage, these soil-borne pathogens have a wide range of hosts and can survive for many years in the soil. Currently, the development of nematode resistant soybean varieties is the most economical and effective means to control nematode damages in soybean production. Discovering novel sources of resistance and increasing available genetic diversity for SCN and RKN resistance are critical for long-term sustainability of host-plant resistance as a tool to combat SCN and RKN. This USB project is composed of six scientists (Drs. Aaron Lorenz, Univ. of Minnesota; Silvia Cianzio, Iowa State Univ; Andrew Scaboo, Univ. of Missouri; Pengyin Chen, Univ. of Missouri; Prakash Arelli, USDA-ARS; Zenglu Li, Univ. of Georgia) from five soybean producing states in the US that tackle the nematode problems, covering maturity from 0 through VIII. Our goals are to identify and utilize novel nematode resistance genetics from exotic soybean germplasm to develop multiple-nematode resistant germplasm lines and breeder-friendly DNA marker assays for marker-assisted selection to support commercial breeding efforts.

The project team had diligently and successfully developed a strong pipeline of soybean germplasm lines with resistance to SCN or RKN and competitive yield across all maturity groups (MG 0-VIII), which have been widely used in both private and public soybean breeding programs. In this project cycle, the team has developed or released 22 soybean germplasm/cultivars across maturity groups 0 to 8 and 22 MATs/transfers involving 19 soybean germplasm lines have been processed to transfer the enhanced germplasm to both private and public soybean breeders

The USB project on nematode resistance discovery and breeding has led to the discovery of putative novel sources of unique nematode resistant lines by Drs. Prakash Arelli and Zenglu Li using a novel genomic strategy. This is the first step to finding new genes to provide broad and more durable resistance in soybean. Based on these new sources, nine genetic populations with these putative novel sources of resistance have been developed with the collaboration efforts by the team. These populations are being used for mapping QTL/genes for SCN resistance and developing improved soybean germplasm with resistance to multiple nematode species.

In addition, the nematode resistance breeding team has published 12 articles in peer-reviewed journals and presented >15 posters or oral presentations at scientific meetings or talks in field days. This work will benefit the entire soybean value chain by providing new elite germplasm adapted to local growing conditions with resistance to SCN or multiple nematode species. It will also provide most desirable source materials to commercial and public breeders for utilizing in their crossing programs for development of high-yielding and nematode resistant germplasm and cultivars. DNA markers and QTL information generated from this project will also benefit all soybean researchers seeking a better understanding of the genetics and mechanisms underlying resistance.