Comparison of the Effects in Field Tests of Soybean Cyst Nematode Resistance Genes from Different Resistance Sources

Abstract

The soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) continues to be the most damaging soybean [Glycine max (L.) Merr.] pathogen in the United States. Many quantitative trait loci (QTL) that confer SCN resistance have been mapped. These QTL include rhg1, which was mapped in several sources of SCN resistance, and two resistance QTL mapped from Glycine soja Siebold & Zucc. The objective of this study was to test the effects of different QTL on SCN reproduction in the field, as well as their associated effects on agronomic traits. Three populations of near isogenic lines (NILs) that segregated for major SCN resistance QTL were developed and planted in field plots in 2006 and 2007. Plant introduction (PI) 88788, PI 437654, and G. soja PI 468916 were the sources of the SCN resistance QTL. Soybean cyst nematode field population densities were estimated from soil samples taken shortly after emergence [initial population density (Pi)] and again close to maturity [final population density (Pf)]. A lower SCN reproductive factor (Rf = Pi/Pf) was found on NILs with the SCN resistance alleles from PI 88788 and PI 468916 (p < 0.05) than those with the susceptibility alleles. The rhg1 allele from PI 88788 was also associated with greater yields in multiple environments than those lines with the susceptibility allele. The results indicate that the rhg1 allele from PI 88788 remains as an effective source of resistance to SCN, and with further research, the SCN resistance QTL alleles from G. soja may serve as a novel source of SCN resistance.