Molecular Breeding for Multi-Nematode Resistance in Soybean.

Soybean nematodes including soybean cyst nematode (SCN), root-knot nematode (RKN) are one of the most destructive pests in soybean production in the world. These nematodes are able to live in the soil for years and cause a significant loss of soybean yield. Phenotyping for nematode resistance is labor intensive and time consuming. Development of nematode resistance soybean cultivars is the most effective way to controlling nematodes in soybean production. PI 96354 was identified having a high level of resistance to RKN galling and egg production. Two QTLs were found to condition the resistance in PI 96354, a major and minor QTL on chromosome 10 and 8, respectively. Using the recombinants derived from the cross of PI 96354 x Bossier as well as soybean reference genome sequence, we have identified four candidate genes with cell-wall modification function responsible for RKN resistance. Two SNPs were selected to develop KASP assays to detect the resistant alleles. Based on the SNP assays, we have developed a high-throughput procedure for seed and leaf samples to select the progeny for RKN resistance in our breeding program. Two genes, Rhg1 and Rhg4 have been widely used for breeding SCN resistance. Based on the previously published results as well as our sequences, three functional SNP markers (two for Rhg1 locus and one for Rhg4 locus) were identified that could provide genotype information for the selection of SCN resistance and differentiate Peking from PI 88788 source for most germplasm lines. The robust KASP SNP marker assays were developed. In most contexts, use of one or two of these markers is sufficient for high-throughput marker-assisted selection of plants that will exhibit SCN resistance.