Association between Soybean Cyst Nematode Resistance Loci and Yield in Soybean

Abstract

Breeding for resistance to soybean cyst nematode (Heterodera glycines Ichinohe; SCN) is an important objective of soybean [Glycine max (L.) Merr.] breeders. There is concern, however, that SCN resistant soybean cultivars yield less than SCN susceptible cultivars under low SCN pressure. This is supported by the report that two quantitative trait loci (QTL) conferring yield depression are linked to the major SCN resistance gene rhg1 on linkage group (LG) G in the resistant plant introduction (PI) 209332. The objective of our study was to test for the association of SCN resistance with yield and other agronomic traits in populations developed from soybean cultivars with resistance derived from PI 88788. We tested five populations of near isogenic lines (NIL) segregating for genetic markers Satt309 or CTA linked to rhg1 and two populations of NILs segregating for Satt431 linked to the resistance QTL cqSCN‐003 on LG J. Population sizes ranged from 23 to 44 NILs, and the populations were yield tested in two years across four locations that had low SCN incidence in previous years. Near isogenic lines predicted to carry the SCN resistance allele yielded significantly (p < 0.05) less than NILs predicted to carry the susceptibility allele in one out of five populations segregating for Satt309 (118 kg ha−1) and in one out of two populations segregating for Satt431 (76 kg ha−1). Significant differences between the two classes of NILs were also observed for plant maturity, plant lodging and plant height in some populations; however, these differences were small in magnitude. Molecular marker data from the NIL populations for the genetic regions flanking the segregating resistance genes suggest the presence of a yield depression QTL distal to rhg1 on LG G and another yield depression QTL linked or pleiotropic to cqSCN‐003 on LG J. Confirmation and refinement of our results will enable soybean breeders to use marker‐assisted breeding to select against yield depressing regions and develop SCN resistant cultivars that compete with SCN susceptible cultivars even under low SCN pressure.