Identification of Loci Underlying Seed Yield in Recombinant Inbred and Near Isogeneic Soybean Lines Derived from Flyer by Hartwig
Two major determinants of soybean [Glycine max (L.) Merr.] seed yield were resistances to the soybean cyst nematode (SCN) and sudden death syndrome (SDS). Two loci were identified rhg1/Rfs2 and rhg3/rfs5 (for resistance to SCN, Heterodera glycines (I.) HG Type 1.3- (race 14), HG Type 0 (race 3) and SDS caused by Fusarium virguliforme (Roy & Rupe)). The aim of this study was to identify quantitative trait loci (QTL) underlying seed yield. Used were 142 microsatellite markers and the recombinant inbred line population (RIL) ‘Flyer’ × ‘Hartwig’ (F × H; n=92). Flyer (F) was high yielding but SCN and SDS susceptible. Hartwig (H) was lower yielding but resistant to all SCN Hg Types and SDS. Four regions on 3 chromosomes were associated with seed yield. The first region on chromosome 9 (Gm9, qYld09.1), identified by the microsatellite marker Satt539-Satt242 (LOD 2.9, 13% variation) derived the beneficial allele from Hartwig (F allele 2.76 ± 0.06 Mg/Ha; H allele 2.98 ± 0.03 Mg/ha). The second region on Gm9 (qYld09.2) between Satt337 and Satt326 spanned 1.4 cM (LOD of 5.31, 20.2% variation) and the beneficial allele derived from Flyer (0.22 Mg/ha F allele 2.98 ± 0.03, H allele 2.77 ± 0.04 Mg/Ha). The third and fourth QTL were identified in genetic linkage groups D2 (qYld19.1) and G (qYld18.1) in regions previously associated with resistance to SCN. The region encompassing rhg1/Rfs2 on Gm18 between the microsatellite marker TMD1 and Satt610 spanned 15.5 cM (LOD 3.05, 15.8 % variation, F allele 2.37 ± 0.035; H allele 2.91 ± 0.058 Mg/Ha). The region on linkage group D2 between Satt514 and Satt488 spanned 32.6 cM (LOD 2.57, Kas13.3% variation, F allele 2.79 ± 0.049; H allele 3.1 ± 0.043 Mg/Ha). The QTL detected will allow marker assisted selection to stack seed yield, with pest resistance traits (rhg1/Rfs2/qYld18.1; H/H/H allele) and recombinant loci (Rhg5/Rfs2/qYld19.1; H/F/H alleles).