Manuscripts

The soybean cyst nematode (SCN) (Heterodera glycinesIchinohe) generates more damage to soybean [Glycine max(L.) Merr.] than any other parasite in most soybean-producing countries. The use of SCN-resistant cultivars remains the most effective method to limit losses caused by SCN. The SCN-resistant accession PI 88788 has been used almost exclusively to control SCN over the past decades, inducing a shift in nematode virulence to overcome the resistance. Furthermore, PI 88788 and other sources of resistance characterized to date belong to maturity groups (MGs) III and higher, making them less attractive to develop early maturing soybean varieties (MGs0-000). In this work, we performed a quantitative trait loci (QTL) analysis of the SCN-resistant soybean accession PI 494182 (MG 0). A recombinant inbred lines (RILs) population (‘Costaud’×PI 494182) segregating for SCN resistance was challenged with SCN (H. glycines[HG] type 0) and genotyped via genotyping-by-sequencing (GBS) to produce a genetic map. Six resistance QTL were identified, including apotentially new resistance locus on chromosome 07. A subset of the RIL population was confronted to a HG type 2.5.7 SCN population and some of these exhibitedresistance toward this type. Whole-genome sequencing of PI 494182 and Costaud allowed us to determine the alleles and their copy number for three candidate genes: GmSNAP11,GmSNAP18(Rhg1), andGmSHMT08(Rhg4). Finally, we determined that selecting for PI 494182 alleles at some SCN-resistance QTL could entail linkage drag (decrease in protein concentration and 100-seed weight, increase in oil concen-tration). This work provides useful markers for introgressing SCN resistance in early maturing soybean varieties.