Updated February 1, 2021:
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 groups 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 diligently and successfully developed a strong pipeline of soybean germplasm lines with resistance to SCN and/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 and released 67 soybean germplasm/cultivars across maturity groups 0 to VIII and 27 MATs/transfers involving soybean germplasm lines have been processed to transfer the enhanced germplasm to both private and public soybean breeders.
The team also focused on discovering new genes/QTL from known sources PI 437654, PI 89772, PI 90763 and other germplasm sources that we identified. This is the first step to finding new genes to provide broad and more durable resistance in soybean. Based on these new sources, numbers of 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 trained four graduate students and two postdoctoral researchers, published or submitted 8 articles in peer-reviewed journals and presented >8 posters or oral presentations at scientific meetings. 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. 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.