New Soybean Accessions Identified with Resistance to Heterodera Glycines Population.

Soybean Cyst Nematode (SCN, Heterodera glycines Ichinohe) is a serious root-parasite of soybean [Glycine max (L.) Merr.], in USA and worldwide. Annual yield losses in USA are estimated to be nearly $1 billion. These losses have remained stable at current levels with the use of resistant cultivars but over time nematode populations will adapt to deployed resistance alleles. Currently available resistant cultivars use fewer sources of resistance, and several major resistance genes are common among them. It is important to identify new accessions with resistance as the first step to finding new alleles to provide more durable resistance. We continue to bioassay newly available accessions in the USDA Soybean Germplasm Collection to identify additional sources of resistance. We have standardized methods for bioassays in the greenhouse and developed near homogeneous nematode populations for stable reactions on soybean plants. We bioassayed 252 new accessions (from PI 567706B to PI 606382B) together with seven indicator lines and two susceptible checks for reaction to two nematode populations, HG Type 2.5.7 and HG Type 0   (commonly known as Race 1 and 3, respectively). Several lines were identified either with resistance or moderate resistance reaction to nematode populations based on the Female Indices. Resistance was confirmed in multiple replicated tests. Data were combined for the tests for ANOVA of female indices by the Statistical Analysis System Software, and means were separated with Fisher’s LSD based on significant F test. We discuss these results.