Discovery of two tightly linked soybean genes at the qSCN10 (O) locus conferring broad-spectrum resistance to soybean cyst nematode.

Abstract

Soybean cyst nematode (SCN, Heterodera glycine Ichinohe) is a major threat to global soybean yield. Resistance genes at the rhg1 locus from PI 88788 are majorly utilized in 95% of the U.S. breeding programs. Continuous use of this resistance source leads to a shift in the virulence of SCN populations and overcomes host resistance. Therefore, it is necessary to identify alternative SCN resistance sources to combat this ever-changing pest. Previously, we identified an exotic soybean line, PI 567516C, which carries a novel qSCN10 (O) locus for SCN resistance demonstrating different resistance responses compared to the known rhg1 and Rhg4 loci. Here, we narrowed the qSCN10 QTL region to 142-kb (containing 20 genes). Based on gene expression, gene ontology, in-silico analysis, and QTL-based haplotyping, two genes were identified for functional characterization. Overexpression of the transcription factor TGA1-related and Shugoshin C-terminus in the SCN-susceptible Williams 82 reduced the cyst number by 6.4-fold (84.6%) and 5.3-fold (81.2%), respectively. GmTGA1-10 and GmSCT-10 Tilling mutants showed high cyst numbers. The two genes associated with the qSCN10 QTL have significant potential to reduce the SCN population. They also offer an alternative source of durable SCN resistance that is independent of rhg1 and Rhg4.