Proteins with Tetratricopeptide-repeat (TPR) domains are encoded by large gene families and distributed in all plant lineages. This study aims to characterize a subfamily of TPR containing proteins named Soluble NSF-Attachment Protein (GmSNAP), of which GmSNAP18 has been reported to mediate resistance to soybean cyst nematode (SCN). This study uses a population of recombinant inbred lines from resistant and susceptible parents to analyse SNAP gene family divergence over time. Five members constitute the soybean SNAP gene family: GmSNAP18, GmSNAP11, GmSNAP14, GmSNAP02, and GmSNAP09. Phylogenetic analysis of genes from 22 diverse plant species showed that SNAP genes were distributed in six monophyletic clades corresponding to the different plant lineages. SNAP genes were duplicated and derived from a common ancestor and unique gene still present in chlorophytic algae. This hypothesis is supported by the conservation of the four TPR motifs in all species, including ancestral lineages. Syntenic analysis of regions harbouring GmSNAP genes reveals that this family arose from segmental and tandem duplications following a tetraploidization event. qRT-PCR analysis of GmSNAP genes indicates a co-regulation following SCN infection. Genetic analysis demonstrates that GmSNAP11 contributes to an additive resistance to SCN. Thus, GmSNAP11 was identified as a novel minor gene conferring resistance to SCN.

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