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 Feng Lin 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 and breeder-friendly DNA marker assays for marker-assisted selection and to develop soybean cultivars with nematode resistance. During FY24, the soybean nematode resistance breeding team achieved significant progress in breeding for nematode resistance and genetic improvement, with key developments as follows: Six new soybean cultivars were developed, including MN0507CN, SA18-12086, SA19-10016, SA19-10772, G17-5173R2 and G21-245R2X (RR2X), with resistance to soybean cyst nematode (SCN) and/or root-knot nematode across maturity groups 0 to VIII. In total, 30 soybean germplasms from the project have been transferred to public and private breeding programs for uses as breeding stocks through Material Transfer Agreements (MTAs) and/ or licensing agreements. New breeding populations were created combining SCN-resistant Peking and other new resistant sources with traits valuable to commodity soybean production and specialty markets, such as high oleic acid, high protein, and food-type soybeans. The gene GmSNAP02, providing resistance against SCN HG type 1.2.5.7 populations, was identified. This discovery, drawing industry interest, has been highlighted in various media outlets. Seven major loci for resistance to five nematode populations were identified using Genome-Wide Association Studies (GWAS). Using a recombinant inbred line (RIL) population derived from Woodruff (carrying Peking-type resistance) and PI, the study confirmed that the best resistance to SCN Race 2 involves combining rhg1-a, rhg2, Chr 11 QTL, and SNAP02-DEL, achieving a favorable average female index (FI) of ~22.5%. Among 629 Glycine max (soybean) lines and 81 Glycine soja lines tested for SCN resistance, several lines were identified with moderate resistance to SCN HG types 0 (Race 3) and 1.2.5.7 (Race 2). While no highly resistant G. soja lines were found, six lines, including PI 468916, showed moderate resistance, which was confirmed through additional testing. Three research papers were published in FY24, one detailing the discovery of GmSNAP02 for nematode resistance, and another on the soybean microbiome’s impact on plant resistance. Two additional manuscripts focused on QTL mapping for SCN resistance are in preparation.

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. Discovered genes and associated DNA markers will provide novel resistance sources and genomic tools for future breeding efforts in combating SCN.