Soybean Cyst Nematode Resistance Quantitative Trait Locus cqSCN-006 Alters the Expression of a c-SNAP Protein

Soybean cyst nematode (SCN) is the most economically damaging pathogen of soybean and host resistance is a core management strategy. The SCN resistance quantitative trait locus cqSCN-006, introgressed from the wild relative Glycine soja, provides intermediate resistance against nematode populations, including those with increased virulence on the heavily used rhg1-b resistance locus. cqSCN-006 was previously fine-mapped to a genome interval on chromosome 15. The present study determined that Glyma.15G191200 at cqSCN-006, encoding a c-SNAP, contributes to SCN resistance. CRISPR/Cas9-mediated disruption of the cqSCN-006 allele reduced SCN resistance in transgenic roots. There are no encoded amino acid polymorphisms between resistant and susceptible alleles. However, other cqSCN-006-specific DNA polymorphisms in the Glyma.15G191200 promoter and gene body were identified, and we observed differing induction of c-SNAP protein abundance at SCN infection sites between resistant and susceptible roots. We identified alternative RNA splice forms transcribed from the Glyma.15G191200 c-SNAP gene and observed differential expression of the splice forms 2 days after SCN infection. Heterologous overexpression of c-SNAPs in plant leaves caused moderate necrosis, suggesting that careful regulation of this protein is required for cellular homeostasis. Apparently, certain G. soja evolved quantitative SCN resistance through altered regulation of c-SNAP. Previous work has demonstrated SCN resistance impacts of the soybean a-SNAP proteins encoded by Glyma.18G022500 (Rhg1) and Glyma.11G234500. The present study shows that a different type of SNAP protein can also impact SCN resistance. Little is known about c-SNAPs in any system, but the present work suggests a role for c-SNAPs during susceptible responses to cyst nematodes.