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. Zenglu Li and Melissa Mitchum, Univ. of Georgia, Aaron Lorenz, Univ. of Minnesota; Asheesh Singh, Iowa State University; and Grover Shannon and Andrew Scaboo, Univ. of Missouri) from four soybean producing states in the US that tackle the nematode problems, covering MGs from 0 through VIII. Our goals were 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 successfully developed a strong pipeline of soybean varieties/germplasm with resistance to SCN and/or RKN and competitive yield across all MGs (MG 0-VIII), which have been widely used in both private and public soybean breeding programs. In this project cycle (FY23), the team has developed and released 10 soybean germplasm/cultivars, which are resistant to SCN and /or root-knot nematode across maturity groups 0 to VIII. Soybean varieties/ germplasm generated in this project have been transferred to 10 private companies/publica breeding programs for use as breeding stocks or commercial cultivars through MTAs or licensing agreements. Five G. soja and 27 G. max accessions with resistance or moderate resistance to SCN HG type 1.2.5.7 (Race 2) populations were identified from more than 600 G. max and 81 G. soja lines screened for SCN resistance. The team also discovered a new gene, GmSNAP02 and other genes, that confers novel SCN resistance, and many private companies have showed interests in the markers and germplasm.
This work will benefit soybean growers by providing new elite cultivars adapted to local growing conditions with resistance to SCN or multiple nematode species. It will also provide germplasm or 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.